OK, today I had 'actual consumption' displayed on the dash (I don't usually have this display mode on, but occasionally I have done). The readout values seemed wierd, quite intermittently erratic.
With an already up to temp engine, starting the engine and driving off sensibly I'd initially be seeing up to 25 L/100km (which seems bad...). This would then quite gradually creep down to more reassuring and expected numbers. Cruising at 100 - 110 kmh on the highway (fairlry level road) I noticed the readout showing over 10 L/100kms, up to about 12 L/100kms on an incline, which seemed abnormal and way more than I've previously seen in similar circumstance (which would be more like 6 or 7 L100kms, + or -). Again, the reading would gradually decrease, but any decent prod on the throttle would see it instantly rise to maybe 19 L/100kms (+ or -), and again take a long time to fall back to reasonable numbers. Backing off completely would see 2 L/100kms displayed (expected), but then even just touching the throttle would see an instant readout often over 10L /100kms (+ or -).
On the return trip the readouts were much more normal, until I experimentally floored the throttle and they shot up again, then started repeating the above behaviour. While this was happening the engine felt less powerful. This wasn't happening all the time, it came and went, and when it wasn't reading wierd numbers the numbers were more or less what I've see before and the engine felt better. Something seems to be responding slowly, at the very least.
So, I'm thinking there is an issue. Maybe the MAF? Maybe one or both O2 sensors?
Thoughts?
Regards,
John.
"Ghosts in the code?" :o
;D
Is it possible that your recent rear brake fiddling has left you with dragging brakes? Easy to check, go for a drive at speed along an open road for a while, coast a stop without using the brake hop out and feel the temps of the rear wheels. The wheels do function as a heat sink and if they are warm to the touch but the fronts are not... bingo. Out of interest is there a big difference with the average & average B fuel consumption figures? Its also possible your fiddling with the RbW throttle may be a factor.
Thanks for the input.
This crossed my mind when I first noticed the strangely high 'Actual Consumption' being shown on the dash. So I coasted to a halt (from 100kmh) and checked the brake temps, i.e. felt them with my hand. The rear brakes were just a bit hotter than the front brakes, but not particularly hot by any measure.
The rear brakes are dragging to some degree, but if this were causing the apparently high intermittent fuel consumption (assuming what the readout is saying is correct), then considering how much extra fuel seems to be being used (when the reading is displaying unusually high numbers, which is intermittent), then the brakes would have to get very hot. All that extra fuel would have to create a lot of energy, and if the high consumption were mainly a product of the drag then that energy would have to end up in the brakes as a very high temperature.
Later I actually stopped, jacked a rear wheel up, and rotated it by hand. I could hear the pads rubbing, but the wheel was easy to rotate. The other rear wheel was just as easy to rotate. I just don't think the drag that exists could be enough to account for the consumption numbers I'm seeing on the display. Put it in neutral and the car coasts a long way as well, and it will pick up speed coasting downhill. It just doesn't feel like the brakes are slowing it any more than is usual.
I can't reconcile the dragging brake idea with the way in which the displayed consumption will go very high with any substantial throttle input, but then only very gradually go down again after lifting off and even decelerating (normally it lowers quickly after lifting off), despite no change in speed (on more or less level roads). If the issue were drag, then I can't see why the high consumption displayed is intermittent, i.e. the displyed numbers can be high or low for periods of time in similar circumstances (i.e. speed, road conditions). It's just a bit strange, something is going on and I'm fairly sure it's something to do with the engine...
The throttle pedal mod is only a simple pedal travel limiter. When I floor the pedal (as far as the limiter allows) the car accelerates well (when it seems to be running properly), and I can actually lift the pedal off the floor by about maybe 5mm before I start to feel acceleration diminish. I can't see how merely preventing the throttle pedal from going all the way to the floor could do wierd things to the fuel consumption.
I still like the limitation on the throttle pedal travel, as it means the engine responds to any pedal movement right up until the pedal is nearly touching the floor, rather than having 'extra' pedal travel that doesn't seem to do anything.
The brake pedal still feels very good, much better than before I tightened the rear caliper piston to pad clearance. I'm quite sure that the previously 'sloppy' brake pedal is a problem associated with the rear caliper design.
Regards,
John.
I think it's probably just how these devices work. Our Subaru has one that shows two concurrent figures, one being an average over the trip since ignition, and the other showing "actual" as you go consumption. If I floor it, it immediately spikes over 20L/100km but then if cruising steadily declines to around the usual average of circa 8/100. It spikes whenever you accelerate and drops when you cruise, but the trip average is usually roughly the same.
The display has two fuel consumption modes. Depress the end of the column stalk once and you get a readout of instantaneous 'actual consumption' (i.e. consumption over the last few seconds of driving), press it again and you get 'average consumption' (i.e. consumption over a much longer distance / time, i.e. since the readout was last cleared, or over up to the last X number of kms). If the average consumtion hasn't been cleared quite recently (by holding the stalk button down for some seconds) then it takes quite a lot of driving in a changed manner (heavier foot, or urban vs highway etc.) for the average consumption readout to change. The 'actual consumption' mode readout changes (should change) very quickly dependant on throttle opening.
It's the 'actual consumption' readout that is behaving strangely here. It used to be different than it is now, in that it used to be consistent with the manner in which the car was being driven at any point in time, but it has now become inconsistent. Sometimes it is behaving as before (as it's supposed to). Sometimes it gives numbers much higher than I was seeing when it was consistently reading 'normally', and then it seems to change back to normal, for a period of time.
When reading normally, the display is quite responsive to reducing throttle position after heavier throttle use, i.e. the numbers quickly reflect lower throttle opening (and apparent lesser fuel usage). When it's reading abnormally the numbers are not very responsive to reduced throttle, they do lower but only very very slowly. It seems as if the the ECU is still fuelling for a wider throttle opening than is actually the case, taking a lot of time to 'catch up' to the fuelling required at a much lesser throttle opening. It's weird.
The numbers I am seeing for larger throttle openings also seem much higher than they used to go. Previously I'd never see numbers over 20L / 100kms when flooring it, now I am easily seeing numbers that high. Note too that when the display is reading stangely that the engine seems a bit 'flat' and less responsive. It also sounds 'flatter' than when the display is reading 'normally'.
My chief suspects are the MAF and the O2 sensors, maybe intermittently reacting slowly to changed conditions(?). Today I think I'll pull the O2 sensors and have a look at them, maybe give them a blast with a blowtorch...
Regards,
John.
Ha, re brake dragging when we lived in Newcastle nearly 20 years ago, I drove a 33 which I think had discs at the front and drums at the back? Anyway, the proportioning valve clogged up and locked the rear brakes on, partially, in the latter part of a 2 hour drive to Forster / Tuncurry. As we got near the town, the terrible hot metal smell I thought was coming from the Land Cruiser in front, stayed with us. I went to brake at the first roundabout and pretty much nothing happened! When I got out to see what was going on, the rear wheels were too hot to touch and the car was pretty much undriveable - had to stay overnight in a motel and drive back in a rental the next day.
To be honest the only thing I find of any practical use is the range indicator. Though I have my doubts about them too. Subaru low fuel warnings start piping up when gauge gets below one "bar" but range indicator still shows +80km. And I doubt it's even that low. I've driven round for days after the range indicator on my old EA Fairmont, and AU falcon was showing zero.
So blasting the O2 sensors with a blowtorch made zero dirrerence, not unexpectedly, it was a long reach at best.
I'm getting no brake 'lock on' of the kind that MattK has reported for his old 33, despite the pads lightly rubbing the rear discs. All this seems to have done is make a substatial improvement to the pedal travel, general brake feel and braking response. I once adjusted the pedal free play to zero (with my old Accord), and prompltly had very similar symptoms to what MattK had with his 33. The slight pedal free play is there for a reason (to ensure that the master cylinder piston seal can't obstruct the pathway between the cylinder bore and the reservoir).
Regards,
John.
The "actual consumption" figures are always buffered, also I note the software doesn't allow such small closed throttle numbers as older ECUs. My '94 Pug will drop to 0.2/100 when coasting in top gear, the 147 never gets close. Many programs won't read higher than 25 or 30/100 so that can be why such a number is seen...
A weakened spark is one reason for possible higher fuel consumption under load, I am starting to think the coil packs don't age well. Have you checked hot, cold, wet, dry compression recently either?
I would expect some degree of buffering, or the readout would likely be unreadable due to moment to moment fluctuation (?). However, the readout is rapidly responsive on the upswing, very not at all on the downswing. The impression is that either the AFR is indeed very slow to lean off (why?), or the readout is not reflecting the reduction in AFR at the rate at which the AFR is actually leaning off.
The impression I have is that a reading of 25 L/100kms is the maximum dispayable readout, even if the momentary real consumption might actually be more than that. I've never seen more than a decimal point free 25 l/100kms displayed, even with a heavy throttle on a cold engine (don't say it, I know, rare occurance when in a big hurry). On cold start up I'm also seeing 25 for a few hunderd metres of light throttle driving (then a slow decrease), which I'm fairly sure it didn't used to do (high teens on cold start up yes, over 20, no...). And, even with an up to temp engine I've been seeing high readouts up to 25 L/100kms after restarting from a short stop (say filling up with fuel), but for a shorter distance.
It's also erratic, for example yesterday; driving at 70kmh on a longish straight flat stretch in fifth gear on a steady whiff of throttle, the readout was a steady 5.5 L/100kms, but later driving the other way on the same road in an identical manner the readout was saying 7.5 to 8 L/100km. This is a pretty big unexplained difference that is hard to reconcile with all working as it should (even if the road in question were on a very slight incline, which it doesn't appear to be).
Haven't checked compression, it doesn't seem like a compression issue. Havn't checked ignition spark strength, doesn't feel like an ignition issue, it never misfires (that I have ever noticed), nor struggles to start easily.
When I had the O2 sensors out they were white and dry with light surface deposits, when I was more half expecting them to be black and sooty (happilly they weren't oily or heavily encrusted with crap suggesting problems with the engine itself, though this would have given an imperative to change the sensors). I guess I'll just throw some sensors (O2 and MAF) on it when disposable funds allow (and keep scratching my head if / when it makes no difference...).
Regards,
John.
Blocked front cats, compromised compression, suboptimal coils are my suite of proposed issues that beset your engine.
Consumption will always drop more slowly than it rises, you have alerted the ECU to a possible need for increased power and there is no way you can instantaneously tell it the request is 100% finished. A bit like spotlighting; see a roo, stop the ute and take aim... Roo hops away before you can safely fire - you don't immediately lower your gun, you keep it raised and steady while you scan around in case there's others.
Anyone ever thought there is a fault in the circuit that calculates the fuel consumption and that there is nothing wrong with the engine. ???
You would be amazed what the mind will do to try and make sense of what it is being told. When the screen tells us there is something wrong we start to imagine all sorts of things to justify what it is telling us. ;)
CB,
wouldn't such issues cause consistent power / consumption problems? My engines' apparent issues seem to be erratic. When my engine is running well, it runs very well, plenty of power for a 2 litre engine (though too much is never enough...), and quite responsive. When it is running badly, it's not hugely worse, just somewhat 'doughy' in comparison (feels somewhat like the ignition has been retarded to some degree).
The 'actual consumption' display can respond very quickly to lessened throttle, but only when the throttle is fully closed (from some degree of being open), when it almost instantly drops to "2L/100kms". I assume the ECU is then taking it's fuelling cue from the throttle potentiometer (whether this is actually a full shut off or only partial, I assume would be for emissions reasons), and ignoring other sensors?.
What appears very odd to me is that any lessened throttle not great enough to trigger effective fuel cut off results in what seems an extremely lethargic response on the display, so if the display is to be believed and the AFR is indeed remaining rich for some time after throttle reduction, then considering that the air flowing into the engine has been significantly reduced by the lessened throttle, then the AFR must (?) be going very rich indeed, i.e. get even richer, at least for a relatively short time until the ECU catches up with what is actually required for a lessened throttle opening...? I can't see why the ECU would have to 'overshoot' the reduced throttle fuelling by nearly as much for as long as it seems it might be doing...
It's my understanding that the ECU would be 'measuring' economy by counting the number and width of injector openings X distance being covered in Y time, so the display should be a reasonably good benchmark for momentary consumption.
Dunno, maybe I should stop thinking about this, for now...
Regards,
John.
It's my personal experience that a failing cat can be intermittent. Whether due to loose parts shifting around in the matrix (ceramic type cats) or raised internal temperature in metal substrate cats actually burning some of the soot to the point where it breaks down and allows partial flow in the affected zone again.
The longer it's left untreated, the more this will impact on the rest of a motor...
As to spurious consumption data, why or how could just that aspect be (digitally) wrong in isolation?
When I come up against a car with anything to do with fuel/AFR/emissions/mileage/poor response/performance or just being temperamental & bitchy I always work on the first principle of Alfas -
MAF, MAF, MAF, Bacon & eggs & MAF, MAF, MAF, MAF, MAF & Chips & MAF.
May I suggest disconnecting the MAF and see if the tangible problems you can physically notice while driving disappear , as the system will be running on the default values. This will no doubt totally pork your fuel consumption values but it will hopefully give you an idea as to if it is the culprit if any of the operational issues disappear or change.
Worth a try maybe? ???
Thanks Bazzbazz,
that's what I need, an experienced opinion / suspicion to give me a reason to try one semi random part throw in preference to another semi random part throw...
How's this for something not right;
Yesterday in town, I had to stop on the street (held up by a car turning left into a driveway), when I see a nearby traffic light that I think is about to turn red, floor the throttle in first gear, car leaps forward enthusiastically and the display instantly goes to apparent 'maximum' (25L/100kms). I make the light (just), jab brakes and calmly turn left. From there, very gentle throttle / low rpm in first gear, second gear, third gear, (fourth gear? can't remember) and the display stays very high (over 20 L/100kms) for the next say 150 metres or so until I halt to turn right. When the car stops the display instantly drops to 2L / 100kms for maybe five seconds until traffic allows me to gently move off, at which point the display instantly jumps to about 18L / 100kms, despite only a whiff of throttle (hardly touched it, honest!). From there for maybe another 70 metres or so (till I park the car) at walking pace / light throttle the display remains no lower than about 16L /100kms (though gradually falling). I'm sure this is abberant...
Note that this was all no faster than the 60kmh speed limit. All the numbers are what I saw on the display, keeping in mind that I had to look at the road too...
A randomly selected comparison; Later that day I was driving a work vehicle (a 2.4L Camry). The 'acutual consumption' display on this car (or whatever Toyota may call it) behaves very differently. If you floor the pedal the display momentarily goes very very high (highest I've seen flash up is 70L / 100kms!!), and when you back off it only takes maybe half a second or so for the display number to plummet, how much depending on how far you've backed off. It can very quickly go from a momentarily frighteningly high number to a single digit number (back off completely and it almost instantly drops to 0L /100kms, but the 147 display also does nearly the same thing in this condition, though only down to a displayed 2L / 100kms). I assume that the 147 display really should behave more or less similarly to that in the Camry, but it it massively different. I vaguely recall driving a BA Falcon that displayed it's instantaneous consumption quite similarly to the Camry, i.e. could see hugely high numbers displayed with a heavy throttle, that then dropped rapidly and very substatially on a reduced throttle.
That this Camry can display such a monstrously high instantaneous number on it's consumption display also gives some weight to the suspicion that the highest number ever shown by the 147s 'actual cunsumption' display (never higher than 25L / 100kms) is indeed very likely to be an arbitrary number, and that the real momentary consumption (as opposed to a seemingly fictional maximum "actual consumption") can most probably be far greater than the display is capable of showing...
Regards,
John.
Quote from: Citroënbender on May 11, 2018, 02:36:51 PM
As to spurious consumption data, why or how could just that aspect be (digitally) wrong in isolation?
A question is; are the displayed numbers spurious?
If yes then this implies a problem with the calculation of the fuel useage by the ECU.
If no, then they are indeed reflecting
actual real consumption (more or less), implying a problem with moment to moment fuelling, and therefore a likely problem with some data being recieved by the ECU. Just what that might be...
Regards,
John.
No range calculator on my V6 156 - I still reset the trip computer every refill just out of habit even though I know I can get at least 620km per tank, driving it in peak hour traffic 4 days a week.
So, ignoring "actual consumption" for the moment, the "average consumption" (as calculated / displayed by the computer) is getting worse than it typically has been for quite some time. The "average consumption" has been hovering around 8.2L/100km (with 'spririted' but not insane driving) for quite a while, but recently has suddenly risen to a quite consistent 8.8L/100km (and I don't think that I've significantly, if at all, changed how hard I've been exercising the engine).
Is this reflecting the suspected 'laggy' AFR richness of the "actual consumption" (on a light throttle after having been at a wider throttle opening)? I don't know, but it's a bit suspicious. For the last few weeks I've strongly suspected that the AFR is remaining quite rich on a trailing throttle (after having been at a wider throttle opening), but then quite slowly settling down to a more reasnable AFR on a steady light throttle. If so, and assuming there actually is a transient over richness occuring, this might be why I'm not seeing evidence of a rich AFR on the plugs, i.e. any carbon deposited on the plugs (and Lambda probes) during transient richness may be burnt off during prolonged light throttle operation?
Some more careful readout observation (of "actual consumption") is suggesting (at least to me...) that the AFR may also be taking some time to enrich adequately when the throttle is snapped open (from light throttle). When the throttle is mashed open (from a steady light throttle), the engine isn't very responsive, but keep the rpm up and throttle opening higher and it is quite responsive, maybe due to the seemingly possible 'lagginess' in the AFR response to changed throttle opening(?). This is suggested by the "actual consumption" display being slow to respond with a higher reading when the throttle is opened quickly from light opening / low rpm.
Today I pulled the O2 sensors out to check them as best I could. According to the 'Lucas Lambda Catalogue" page, a rough and ready test of O2 sensor function can be done by heating the sensor probe and measuring the voltage output as follows:
".... now connect the voltmeter red probe to the signal wire (generally black) and the black probe to the earth (generally grey) and set voltmeter to .000 volts. Then with a propane torch heat up the tip of the sensor until it is cherry red. The sensor should give off a reading of nearly 1 volt in a few seconds. If it takes longer than 20 seconds to get a reasonable reading change the sensor."
So, following the directions I find that both sensors seem slow to produce respectable voltage, but perhaps more tellingly one is substantially slower than the other is. I think my next move is to change both upstream O2 sensors, and see what happens.
Anyone have any bad experience using 'universal' zirconia lambda senors on Alfas? I've used them before on other cars with no problems, and my understanding is that a 4 wire zirconia sensor should be a 4 wire zirconia sensor should be a 4 wire zirconia sensor. But I have heard random stories of universals not working well with some cars. The Lucas page also says that universals probably won't work properly for most cars after about MY2000, but then further into the text it appears that this applies to titania sensors, not zirconia sensors (as the 147 sensors are).
Regards,
John.
Why not invest in a laptop and MES at this point?
Parts roulette is not going to return overly useful real time info and you can only go by passive inspections - vs live data.
CB,
Good advice.
I do have a code reader, but it won't "establish a connection" with the 147 (or the Saab for that matter). I don't own a laptop, so would have to aqcuire one (my wife has one, but she's possessively paranoid about it, that it could get stuffed up if she lets anyone use it unsupervised, so to ask would be to burn marital brownie points...). I might see if I can find a cheap obsolete used one.
I do agree that parts roulette is generally a poor strategy, but the O2 sensors are not unlikely to be the original ones (at least there is no record of them ever having been replaced), so likely due for changing anyway. That each one behaves quite differently to the other (re voltage output) when heated does suggest that at least one is not up to scratch, so I don't think replacement is an irrational move...
Regards,
John.
A laptop running XP Pro is sufficient. It will need a memory upgrade if still "as sold". It will also benefit from installing Firefox as an aid to downloading various bits of supporting software. This should come in under $200 if you look around.
Cheap code readers are generally not worth the distraction. With good cables and a franchised version of diagnostic software you will be a long way ahead.
A oxy sensor that doesn't look sooty or have over 160K should be doing its job just fine.
Quote from: Citroënbender on May 31, 2018, 11:12:54 AM
A oxy sensor that doesn't look sooty or have over 160K should be doing its job just fine.
If I make the (I think) reasonable assumption that the sensors are probably the original fitment, then they are now 210,000km old. So, it would not be suprising if they were to be somewhat knackered (maybe more surprising if they weren't?), or if not then are not unlikely to be less than healthy soonish ...
Considering this, and that average fuel consumption appears to be on the rise, with weird transient "actual consumption" readouts, as well as there being erraticish driveabilty issues, I doubt that a pair of new sensors would be a complete waste of money. That they are not sooty in appearance does go against this rationalisation, but my suspicion is that the AFR may be reasonably OK much of the time (longer periods of steady state light throttle), so any tell tale sootiness might possibly be burned off under these conditions...?
Regards,
John.
It'd be a cheaper test of your premise to fit a pair of used but tested sensors, any gross deviation would be readily apparent.
So, we didn't bother with the MAF then? (cleaning for example)
90% of the time when diagnostics throw up a O2 sensor error it is actually caused by the MAF (which only ever shows up as faulty when it's totally dead), feeding misleading data into the ECU which leads to erroneous operation and indication from the O2 sensors.
Not saying that the O2 sensors don't need replacing but you ALWAYS suspect the MAF first in these circumstances.
Bazz,
Yes, we did clean the MAF. I took it out 'properly', i.e removing it from the tube case to get a good look and good access for cleaning. It looked clean as a whistle, but I sprayed it thouroughly anyway. No change.
I then tried an ECU 'reset' (disconnect battery for 45 minutes, reconnect, turn to 'MAR' for 90 seconds, etc. etc.). Whether this is a true ECU reboot I'm not sure, but it seems to have worked for some people (if the internet can be believed...).
Anyway, this did have an effect, a bad one. The engine seemed more 'doughy' than it had before, but at least with some k's over a few days it has improved back to how it was.
I haven't discounted the MAF, it might still be an issue, but one thing at a time...
CB,
I agree, it would be cheaper just to throw some O2 sensors at it, and see. Business is down just now, so cash is an issue. I can't see myself paying whatever it might be for new direct replacement sensors, so it looks like some universals, or, as you suggest see if I can pick up a couple of matched low km sensors from a wrecker (needn't be from an Alfa, any 4 wire zirconia sensors should work, at least that is my understanding...).
Regards,
John.
Quote from: johnl on May 31, 2018, 05:43:54 PM
I then tried an ECU 'reset' (disconnect battery for 45 minutes, reconnect, turn to 'MAR' for 90 seconds, etc. etc.). Whether this is a true ECU reboot I'm not sure, but it seems to have worked for some people (if the internet can be believed...).
On your 147 that procedure will only do a Throttle Reset, it will have NO EFFECT on the Adaptive Parameters of the engine ECU. You need one of the Alfa Romeo diagnostic suites to do that.
The ONLY car that that procedure will work on is the Alfa 156 Selespeed with Bosch 3.1 ECU.
Also if you change any of the engine Management Sensors, such as O2 sensors, one needs to do a Adaptive Parameter Reset with the Diagnostics. Few people realize this.
As per MES -
If some elements such as the minimum actuator, the Lambda probe or the knock sensor are replaced, the function lets the ECU return the adjustment parameters to initial values so as to correctly manage the new component.Quote from: johnl on May 31, 2018, 05:43:54 PM
Bazz,
Yes, we did clean the MAF. I took it out 'properly', i.e removing it from the tube case to get a good look and good access for cleaning. It looked clean as a whistle, but I sprayed it thouroughly anyway. No change.
As you no doubt are well aware of, a clean MAF can still be a faulty MAF.
As for O2 sensors, you can pick up brand new genuine Bosch units for a good price these days -
https://www.ebay.com.au/itm/Bosch-0258006389-Oxygen-Sensor/232754279789?fits=Make%3AAlfa+Romeo%7CModel%3A147&epid=244826859&hash=item36313c756d:g:fD4AAOSwoKFa6dmj (https://www.ebay.com.au/itm/Bosch-0258006389-Oxygen-Sensor/232754279789?fits=Make%3AAlfa+Romeo%7CModel%3A147&epid=244826859&hash=item36313c756d:g:fD4AAOSwoKFa6dmj)
Worth following this auction, a durable machine you can load up with a variety of diagnostics programs.
https://www.ebay.com.au/itm/292583278633
Then you can watch one forward sensor independently of the other; reduces guesswork.
Last I looked, I had three or four used 147 oxy sensors laying around.
Quote from: bazzbazz on May 31, 2018, 06:53:24 PM
On your 147 that procedure will only do a Throttle Reset, it will have NO EFFECT on the Adaptive Parameters of the engine ECU. You need one of the Alfa Romeo diagnostic suites to do that.
Understood, thanks Bazz.
I felt it had some affect (if only on the throttle behaviour...), because the engine seemed less responsive for some time afterward, and then improved (scientifically validated with the 'buttometer'...). Placebo? I wasn't expecting it to be better after the 'reset', but was hoping it might be, but it actually seemed worse, when the worst I thought likely was no change...
Quote from: bazzbazz on May 31, 2018, 06:53:24 PM
Also if you change any of the engine Management Sensors, such as O2 sensors, one needs to do a Adaptive Parameter Reset with the Diagnostics. Few people realize this.
As per MES -
If some elements such as the minimum actuator, the Lambda probe or the knock sensor are replaced, the function lets the ECU return the adjustment parameters to initial values so as to correctly manage the new component.
I didn't. Does failure to reset in the prescribed manner prevent the ECU from adapting to new sensor parameters, or merely slow this down?
Whatever, it appears that electronic access will become a necessity some time quite soon...
Quote from: bazzbazz on May 31, 2018, 06:53:24 PM
As you no doubt are well aware of, a clean MAF can still be a faulty MAF.
Of course. I wasn't assuming that no change (as a result of cleaning) meant it must be good...
Quote from: bazzbazz on May 31, 2018, 06:53:24 PM
As for O2 sensors, you can pick up brand new genuine Bosch units for a good price these days -
That's a good price for a 'correct' sensor. Doesn't mean I can afford two of them just now with other large outgoings looming, unless I put it on the dreaded plastic...
I still wonder if it is actually necessary to use 'correct' O2 sensors, or whether generic sensors of the appropriate type (i.e 4 wire zirconia) will work acceptably, or any differently at all?
Regards,
John.
Quote from: johnl on May 31, 2018, 11:01:55 PM
That's a good price for a 'correct' sensor. Doesn't mean I can afford two of them just now with other large outgoings looming, unless I put it on the dreaded plastic...
Yes,
"being about as financial as a Greek Bank!" is something I too am all too familiar with. :-\
A universal Bosch or NTK sensor will work fine with one caveat - the wiring connections must be 100%...
Also, I am not convinced it will give meaningful data. Changing one sensor is highly unlikely to provide a change in fuel consumption that can be simply correlated to a notional "before" number.
Quote from: Citroënbender on June 01, 2018, 04:45:56 AM
A universal Bosch or NTK sensor will work fine with one caveat - the wiring connections must be 100%...
Of course. So very clean wires / 'crimp' connectors, and, make sure that air can get in between the wire insulation and the wire metal, so no solder that could conceivably block airflow or tight fitting shrink wrap covering the point where the insulation ends.
Quote from: Citroënbender on June 01, 2018, 04:45:56 AMAlso, I am not convinced it will give meaningful data. Changing one sensor is highly unlikely to provide a change in fuel consumption that can be simply correlated to a notional "before" number.
I'm not sure I follow what you mean. If an O2 sensor is misreporting then the ECU has no way to 'know' this (if ECUs have a god, it is the O2 sensor, which they tend to believe 'religiously'). I've had an O2 sensor failure (on the Saab) so bad that the plugs would foul very quickly and the engine run obviously very rich and rough, with extremely poor fuel economy and low power, but still no engine check light. My experience suggests that ECUs seem fairly blind to O2 sensor faults, with faulty sensors generally reporting lean, so the ECU inappropriately and (possibly) enthusiastically enriches, with substantial impact on economy. Changing a bad sensor for a good sensor would surely improve this (certainly did with the Saab, dramatically).
In this case (my 147) I'm suspecting the sensors are not so much reporting lean, but reporting very slowly, so failing to report a lean condition
quickly enough when the throttle is opened (airflow increases, so AFR goes lean until ECU corrects it, lazily), and then failing to report a rich condition quickly enough when the throttle opening is lessened (airflow decreases, so AFR remains rich until ECU corrects, eventually...). The ECU can only correct AFR based on 'data in' from the O2 sensors. Slow reporting of 'lean' seems not as slow as glacial reporting of 'rich'. In either case I think the sensors probably eventually get near enough to the correct voltage output, just way too slowly.
As should be clear from what I've been saying, this suspicion is not directly informed by data that might be available if I could interrogate the ECU, I'm just making inferences based on the behaviour of the 'actual consumption' readout (which I'm fairly sure is letting me know that something is not as it should be, and from there I'm having a stab...). This doesn't preclude the possibility that I'm barking up the wrong tree, and that the issue could instead be the MAF rather than the O2 sensors, or a combination of both MAF and O2 sensor...
Regards,
John.
It's going to be at the earliest Saturday night before I can respond to this in more detail. But the thrust of my comments is as stated prior; it's about conservative spending for concrete gains vs punting.
I've had a brief skim of your prior posts and note:
Thermostat fitted 2016-ish - this should still be OK.
Two injectors replaced due to being "stuck open". This could predicate bore wear, surely?
Can't find your compression test results (hot, cold, wet, dry) from the last few years.
So maybe if we could start with some data there, using a screw-in type gauge?
Quote from: Citroënbender on June 09, 2018, 11:05:10 PM
Two injectors replaced due to being "stuck open". This could predicate bore wear, surely?
Can't find your compression test results (hot, cold, wet, dry) from the last few years.
So maybe if we could start with some data there, using a screw-in type gauge?
Hi CB,
I doubt that the two injector failures would have had time to cause appreciable bore wear. The failures (appeared to be) very sudden, one day the engine was running fine, the next day black smoke and very rough running. In fact so sudden that the two journeys in which both failures occurred started with the engine running well, but ended with an engine that abruptly became sick near the end of the trip. It would not have been many kms driving with the bores being 'washed' of oil, just a handful. Note that each failure was in a different cylinder, so no cumulative KMs for any cylinder.
Having said that, a compression test isn't a bad idea, not that I have any strong reason to suspect poor compresion as the engine runs very well when it's running well (usually in colder ambient temperatures, it's on hot days that the performance tends to become a bit 'doughy'). Now, I have owned at least two compression testers over the years, the first one died, the second one just disappeared at some stage. I do need to buy another one, sometime...
My engine does use oil (big surprise there...). I suspect it's likely to be the valve stem seals, since the only time oil smoke is ever evident is at start up (and then only occasionally). Oil consumption is rather sporadic, the engine might go a week or two without needing a top up, then might lose half a litre in a couple of days. Whatever, this does mean that some oil will be getting into the exhaust system, and thus onto the O2 sensors. I have two new O2 sensors on the way from the UK.
I'm considering changing the oil to a different oil, because the 'fully synthetic" Penrite oil I've been using has a significant zinc content (very good for lubricating sliding surfaces, such as cam lobes, the most highly loaded / stressed surfaces in an engine). It's enough that you can smell it in the exhaust smoke (when smoke is actually evident at start up). The smoke smells distinctively like differential oil, which has a very high zinc content to protect the 'hypoid' crown and pinion gears as found in most RWD diferentials (hypoid gears slide substantially against each other as they rotate).
My thinking is that zinc is known to be bad for O2 sensors, so an engine that burns a significant amount of zinc laden oil may well be at added risk of damaging it's O2 sensors....
Regards,
John.
Quote from: johnl on June 10, 2018, 01:22:37 PM
The smoke smells distinctively like differential oil
Ah-ha. Pull the upper two O2 sensors and have a peek down the holes and take a look at the Catalytic Converter cores. If you can't see, borrow a inspection camera or just use something appropriate to insert down the O2 sensor hole to see how far it goes. You may be surprised to see just how far it goes down, as in like "It should hit the core by now . . . . .it REALLY should have hit the core by now??" ;)
Hi Bazz,
Why would some issue with the pre-cats cause burning engine oil to smell like zincy differential oil?
I did just find an oil film on one of the header pipes, where a drop of oil had obviously dripped onto the pipe (and spread out). This might explain some of the zincy oil aroma I have occasionally smelt (though I haven't previously seen evidence of oil on the pipe, I assume because it has burnt off). This is annoying because the cam cover gasket must be leaking, and it's only fairly recently been replaced...
Anyway, as per your suggestion I pulled the O2 sensors and peeked in. What I found was, nothing suspicious. The core matrixes (matrixi ?) both look clean, unobstructed, unmelted, uneroded and otherwise intact, with a mid to darkish grey colour. I couldn't see the entirety of the matix 'faces', only what the hole permitted (I don't have a techy little camera...), so this might not be a 'definitive peek', but I'm pretty sure what I couldn't see would probably look the same.
Something I did note, that I also saw the last time I pulled the sensors out (i.e. seen it more than one time, so it seems likely to be a fairly consistent thing...);
One of the probes (right side as viewed from the front of the car) is a fairly uniform light grey colour over most if its' surface (other than the very tip, which is a significantly lighter grey). The other probe is more or less the same, but for a quite distinct / defined band of dry black sootiness about 5 or 6mm in width around the entire circumference of the cylindrical part of the probe (next to the threads). Both sensors are quite dry, no sign of oiliness.
This at least suggests that something in some way somewhat different is happening to the AFR in cylinders 1 and 4 as opposed to 2 and 3. Since one sensor is associated with cylinders 1 and 4, and the other associated with 2 and 3, is it a stretch to suspect that this might not be related to some difference between the way in which one sensor is behaving (voltage to ECU) relative to the other sensor...? I tend to think not...
Regards,
John.
This seemingly persistent band of black soot on only one sensor suggests (to me) that at some point this sensor is probably having soot deposited over the entire probe surface, which then gets burnt off depending on how hot any given part of the probe may get.
The part of the probe directly adjacent to the wall of the exhaust (pre cat canister) would be kept cooler due to it's proximity to the relatively cool wall (which will be radiating substantial heat away, 'pulling' heat from the probe). Exhaust gasses will also tend to be hotter toward the middle of the exhaust flow, and cooler adjacent to the wall. Soot deposited on the probe near the wall would be less likely to burn off. The parts of the probe that are further from the wall, and more directly in the strong flow of the uncooled hot exhaust gasses, would remain hotter, so carbon deposits would burn off much more readily from those parts of the probe.
Questions might be; due to a possibly richer AFR in cylinders 1 / 4 relative to 2 / 3, is one probe being deposited with unburnt carbon and the other not? Or; are both probes having carbon deposited on them, but one is getting hotter than the other due to a difference in AFR (and thus exhaust gas temperature) between cylinders 1 / 4 and cylinders 2 / 3? I suppose either is possible.
Can't wait for my new sensors. But I'll be disappointed if they make zero difference...
Regards,
John.
Have you pulled spark plug #1 recently and checked it?
If you pull plug #1 and it is oily and all the rest are fine you will find that you have a failed inlet manifold gasket around the oil gallery area for the Variator Solenoid.
This is an old problem in these engines. Read post #4
http://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/196687-156-ts-oil-contamination-in-inlet-manifold.html (http://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/196687-156-ts-oil-contamination-in-inlet-manifold.html)
Quote from: bazzbazz on June 10, 2018, 05:49:58 PM
Have you pulled spark plug #1 recently and checked it?
Yes, a few weeks ago. All plugs looked OK and similar. They are relatively new plugs, well under the 100,000 km interval. Wouldn't hurt to have another look at them.
Regards,
John.
Quote from: bazzbazz on June 10, 2018, 05:49:58 PM
Have you pulled spark plug #1 recently and checked it?
If you pull plug #1 and it is oily and all the rest are fine you will find that you have a failed inlet manifold gasket around the oil gallery area for the Variator Solenoid.
So I checked the spark plugs, which all looked OK. (I also took the cam cover off, cleaned everything, and refitted the gasket smeared with a liberal amount of anaerobic 'gasket maker', which has fixed the annoying oil leak).
I received the new O2 sensors some days ago (RTG brand 'universal' sensors, that needed to be fitted to the old plugs with crimp connectors). After fitting them I zeroed the 'average consumption' readout.
Afterward, at first I was seeing 'average consumption' readouts quite a bit lower than before the sensor change, around 8.3L/100km give or take (as opposed to a consistent 8.8L/100km with the old sensors). But, after a few days and a few hundred km of driving the 'average consumption' readout has risen to a consistent 8.5L/100km (still a significant if not huge improvement). This included one trip towing a trailer laden with maybe 200kg (or so, thereabouts, best guess) of firewood, largely uphill...
With similar light throttle openings I'm now seeing 'actual consumption' numbers that are significantly lower than I was seeing with the old sensors, but the readout still seems slow to react to reduced throttle (not much change to
rate of response to reduced throttle, though the readout does tend to fall to a lower number in whatever time it takes). On very light throttle openings I'm now often seeing 'actual consumption' readouts around and below 4L/100km, whereas before I almost never saw less than 6L/100km (ignoring closed throttle when the display is and was 2L/100km).
I can't entirely rule out a placebo effect, but since I changed the sensors the engine feels to be running quite significantly better. I feel like I'm needing to use lesser throttle openings to cruise and climb inclines / hills, and the engine feels happier to do so in a higher gear. Response to opening the throttle feels better, I'm not as often feeling the need to change down a gear for the engine to do what I want it to do. It feels more responsive and a bit less 'fluffy', 'crisper', and generally more 'enthusiastic' to move down the road (the car feels as if it were a bit lighter in weight...).
I might be comparing an apple to an orange though. The engine used to feel a bit 'doughy' and otherwise less than great on hot days (and better on cold days), but since fitting the new sensors we haven't had any of those, winter has finally come.
I suspect that because the engine now feels a bit 'happier' and more 'willing', I'm tending to drive it just a bit harder than I was doing before the sensor change. If so then the apparent improvement in 'average consumption' could be a bit misleading, i.e. if my driving habit were to be identical to previously, then the 'new' economy might possibly be a bit better than the readout numbers suggest.
Regards,
John.
John, is your car still producing that horrible burnt diff oil smell from the exhaust?
If so you may like to check this out -
https://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/1164765-smelly-jts.html#post17272173 (https://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/1164765-smelly-jts.html#post17272173)
Quote from: bazzbazz on June 30, 2018, 07:04:32 PM
John, is your car still producing that horrible burnt diff oil smell from the exhaust?
If so you may like to check this out -
https://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/1164765-smelly-jts.html#post17272173 (https://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/1164765-smelly-jts.html#post17272173)
Baz,
If you look carefully you'll see a contributor to that topic named 'johnlear', who is me, my secret identity. You might be excused for not twigging since the disguise is so cunning...
My car has ceased occasionally smelling like burnt differential oil, because I've fixed the cam cover oil leak. Due to this leak, and because I'm running the engine sans exhaust manifold heat shield, every now and then a drop of oil would fall onto one of the hot naked header tubes, which would instantly vapourise and create a short lived pong that would reach into the cabin.
The (other) smoke emanating from the end of the exhaust only briefly occurs (as far as I am aware) at start up after the engine has been shut down for some while, and then only on the odd occasion. I suspect leaky valve stem seals, the symptom is classic for that issue. This smoke does smell (like burnt diff oil), but the smoke is rare and at the rear of the car, so I almost never actually smell it, only see it briefly in the rear view mirror as I drive off, or as I reverse into its' haze.
I'm sure it's not related to sensors, cats, AFR. It's just a very minor issue, that over time will inexorably become a bigger problem...
Regards,
John.
Ahh yes, I did twig, my direction to the post did steep in a little sarcasm. ;)
And yes, your quite right about the stem seals.
My manual 147 is not 100% happy at present, suspect another pair of coil packs is ailing. However, I did a run from north of Newie back to Sydney last Thursday night and got 7.3/100 on the average (display, not calculated). That included some pretty serious rain with a slight wind thrown in as well.
If economy is what one seeks simply drive your car using the cruise control as much as possible. By doing so I get 6.8 - 6.9L/100km
with my 156 JTS Wagon. And that's city/urban combined.
Just an update. The 'average consumption' is still consistant at 8.5L / 100km (down from consistently 8.8L with the old sensors). This does seem to suggest that the old sensors weren't in the best shape, so not a waste of money buying new ones without proof that the old were bad. But how many kms before they pay for themselves with fuel savings I haven't bothered to calculate....
The engine is definitely running more sweetly with the new sensors, with no instance (yet) of the intermittent 'doughiness' that was happening previously. However, it's still cool weather, warmer days will tell since higher ambient temperarture was what seemed to make the doughiness worse...
Regards,
John.
I find the best way to feel good about fuel consumption is to own two different generations of Alfas.
My daily 19yo 2.5L V6 156 on average achieves about 10L/100km - which I imagine would be considered thirsty by many folks these days.
Whereas my 37yo 2L four cylinder GTV with twin 45mm Webers achieves about 15L/100km on average.
So to my mind, the 156 is as frugal as a Franciscan monk! :D
Quote from: poohbah on July 02, 2018, 07:42:06 PMI find the best way to feel good about fuel consumption is to own two different generations of Alfas.
People fixate on consumption. The net cost per km is more interesting to me, if one keeps it a reasonably current calculation. If we think we're doing well because the car is using less fuel, we're probably overlooking that the "saving" could be spent elsewhere in maintaining or improving said vehicle. :)
I most definitely do not factor in maintenance costs. That would just make me cry.