3.2 Q4 JTS ASR/Hill Start/Fuel gauge Failure.

[Ascari32]

Has anyone any clues as to why the ASR/VDC/Hill Start and Petrol Gauge should fail in unison on my 3.2 Q4 JTS. I am inclined to think it is related to some bad connection or moisture - it has been getting colder and damp of late. It would be nice to think it is something obvious, but history tells a different story. I do hope it's not some terminal software failure. Aside from these failure indications, the car is running nicely.

And advice would be most welcome.

Cheers,

[bazzbazz]

The USUAL cause is you have lost the connection to your MAF.

Either the MAF has died completely (rare) or the connection to it is bad.

Try disconnecting and cleaning the plug and reconnecting. If the fuel gauge suddenly works you have found the culprit.

[Ascari32]

OK, here's the story. My New camshafts have such a massive valve overlap that the air through the MAF is such that it creates an error which the ECU is unaware of. New MAF flow based on cylinder fill + Crossflow.

So, after much testing I buy a new MAF sensor Bosch 0-280-218-008; fits Volvo XC70. But, it still needed a little "Tailoring" to work - get tick-over volume down.

Anyway, after much investigation trying various test components, I settle for 10k ohms in series with pin (5) the MAF output signal. Lovely, just the job. However my tinkering around the MAF has been going on for about a week and although the alarm indications came up yesterday, I made no connection with them and the MAF as the car/engine continued to respond nicely to my tests, getting better, then worse, then finally better as I swapped components in and out.

So earlier today, having settled on the final value, I phone my local garage to book the car in to have this problem investigated. At the same time, I post for any help in trying to understand why I now have these failures.

To which, a prompt response points me in the direction of the MAF, with the prospect of it having failed at worst. However, was I being sent - up? What could possibly be the connection between the Hill Start handbrake function, the ASR, the VDC and the Fuel Gauge?

Feeling a bit of an idiot, I go out to the car - having just got back from the garden centre - and do as was suggested by bazzbazz, disconnect the MAF plug, give it the once over and firmly plug it back into the element.

Key - in, depress the clutch and press the starter button. Bingo!!!!!!!!!!!!!! The logic is lost on me, yet another mystery surrounding this enigmatic car.

But, none the less grateful to bazzbazz for his insight - top man! One more issue ticked - off the list. Car is now running very much quieter than when I started all this malarkey. Just marginally noisier than a standard 3.2JTS. No resonance, sporty character to the exhaust system - right across the revs - Alfetta 3.0 like. Bags of pep on the throttle. In fact it is so different - I am persuading myself, rather than cancel the garage, to give my new boxes another chance. If they work, I am going to be one very, very happy bunny.

Thanks again Bazz!   
   

[Colin Edwards]

When I had ASR/VDC/Hill Start issues the root cause was failure of the brake switch, or more to the point, poor adjustment. 
A simple resetting of the switch position cured the issue.

[bazzbazz]

When I had ASR/VDC/Hill Start issues the root cause was failure of the brake switch, or more to the point, poor adjustment. 
A simple resetting of the switch position cured the issue.

Yes, but the key indicator here was in addition the fuel gauge crashing to zero.

[Ascari32]

Well, true to form, things aren't as simple as it seems. Bazz pointed me in the right direction and that was that - or so I thought.

It was pure hypothesis about increased air flow due the changed valve timing and it seems a reasonable one at that. However, the ASR/VDC, Hill start and fuel gauge failed again. So further investigation was needed. Bazz is absolutely spot on wrt the MAF association. However, in reducing the current in the output to the ECU, I prompted a loop - sense fail. But the fact that I could reduce the "Power" in the tick - over, by trimming the current indicated air flow was affecting the ECU's ability to set the correct air fuel ratio. So I am on the right track. Just I can't trim the output of the MAF to adjust it, and expect the ECU not to display these failures.

Although the engine runs well, one cannot drive around with these failures permanently displayed on the dash. Although, it has to be said, with the 10k ohm in the output, the tick - over became the same volume as when I disconnected the MAF connector.

So, it seems I am being drawn towards remapping, which is not something I would willingly choose to do. The new Volvo XC70 senor is working brilliantly but the idle airflow is still sufficient to cause an output from the sensor, which it should not. This not only affects the tick - over, but the overall economy, given on lift of, fuel injected should fall to that which it is at idle.

So as an alternative, I may try to modify the flow characteristics through the MAF Venturi tube, or even change the whole of the inlet ducting. I shall have to do some more research/testing in the hope there may be some clues on how to achieve it, by way of a different MAF Venturi or reducing the airflow through the internal Venturi, in which the element sits. Essentially, the MAF body is a Double Venturi, the smaller enclosing the sensor, whilst it is located in the main body.

There must be a solution to this problem, even if it means a complete re-work of the inlet ducting. Just not yet thought too deeply about how to achieve it. The problem seems simple, yet the solution much less so.

Hey! Ho! The project goes on! Both fascinating and frustrating. Would I want it any other way? Probably not. Simple things aren't projects, they are just routine - and pretty boring to boot!

[Ascari32]

Hi!

Well given I started this thread, it seems only right that I should close it out, unless of course anyone else has something to add. Quite pleased that I gave sufficient detail in the title for BazzBazz to point me in the right direction. Given I was experimenting the with the MAF of my 3.2 JTS, it just tied in nicely and from then on things fell into place. Meaning, there was sufficient evidence to persuade me my outstanding problems revolved around the MAF output signal.

My current thinking is, whilst the Butterfly (Throttle) was closed, the MAF output voltage did not correlate with the conditions for proper idle and so the ECU was still reading the manifold lambda probes and attempting to set the AFR, despite both the inlet and exhaust VVT Solenoid Valves being in their "Default" positions, ie., inlet camshaft, fully retarded; exhaust camshaft, fully advanced. Hence the "Audibly Powerful tick - over at 750 rpm.

It is clear from the Bosch Data Sheets, the devices which have the greatest Kg./Hr. flow rates, do not specify and output voltage at the lower end, whereas, MAF elements, clearly intended for lower capacity/less powerful cars do! And because my original element was producing an output voltage, but behaving normally in every other respect, I am convinced it was the wrong element all along.

With the increased flow rate due to cross - flow/PVO, which my Colombo Bariani Camshafts introduce, an output voltage was being created which fooled the ECU into continuing to read the manifold lambdas, and attempting to set an Air Flow Ratio appropriate for minimizing emissions. This; I believe, caused the Lambda output signal (voltage) to induce the ECU to modify the fuel metering to the extent that it went beyond the range which could control emissions. Hence the Engine Management Code failures.   

The element now fitted is a 98660612501, AKA 280 - 218 - 055, which; as it transpires is fitted to 911 Porsche 3.8/4.0 Litre Turbo's and Ferrari 599 GT. This according to published details is also fitted as standard to the 3.2 JTS, although Alfa have gone to great lengths to disguise the fact.

None the less, the engine is now performing beautifully, particularly at Idle where one would be hard pressed to believe it is the same car as before the element was changed. Tick - over is particularly quiet now and the engine has remained free of any management failings/codes. I have concluded, the MAF element which was originally fitted was not the correct device, raising suspicions about some aspects of engine maintenance, prior to my purchase. However, the engine in the car now is a fully balanced and modified Brera engine, with cam, exhaust and header modifications. The Alfa rear boxes remain fitted but I shall soon be refitting the Ascaris. given I now have confidence that they will perform better than hitherto.

Thanks again to Bazz for a very swift response to this issue which saved an awful lot of time and grief. It would have taken me considerably longer to resolve this issue, had he not picked up on it very quickly. Particularly when he intuitively linked all the elements together.

Cheers.

[bazzbazz]

One is glad to be of service.

[specimenX]

I'm not sure where you have gathered the published details for MAF inserts( i suspect chinese site) as  0280218055 is not the correct MAF insert fitted to 3.2 JTS. The 3.2 maf insert can be found on engines with less than 75Kw output. You could always contact Bosch for accurate information, in the past i've found them very obliging.

[Ascari32]

Well, it really is a question of what to believe, particularly when it comes to anything on the internet.

The response curves for the 2.0, 3.0 GTV and the 008 are taken from Bosch data sheets. So too the “421” which is the highest rated I could find. I could not find anyone who could supply it. Also, the Porsche is no longer available from them. But I was given the 98660612501/055 as direct replacements.

I have contacted Bosch and they were far from helpful, suggesting I speak with the manufacturer - Alfa, suggesting to me, the precise details were exclusive to Alfa. And of course Alfa won’t disclose any information beyond selling me a replacement, at their ridiculously over inflated price.

No matter, it was the 98660612501/055 I had been looking for which I am informed by several sources is the correct one for the 911 up to 4.0 litre. Also quoted for the 599 GT. And the 3.2 JTS.

It would not surprise me that this element has been “Tweeked” for Alfa as their valve timing creates the need for a very fast response at the bottom end. That would tie in with what you say of engines up to 75 kW., which is evidenced by the much more acute slope of the lower Kg./Hr. elements for smaller capacity engines - as per Bosch data sheets. Indeed I have written, “The Alfa Insert response is probably more acute than that of (1) of the Bosch data sheets”.

Essentially there is little difference between all of the devices I have mentioned. It is just the way they are aligned that differentiates them. With a calibrated source, I could align them my self to match the engines characteristics.

None the less, I am happy with the 055 performance, both because of the super smooth idle, which I confess seems unusually subdued for a sports system, and the really crisp way the engine responds to the foot. It, undoubtedly will not be bang - on, but until I get it on the Dynamometer, I won’t know precisely how far it may be out.

The important point being, with such dramatic changes to valve timing, it required, in my opinion, a gentler Transfer Charcteristic. With the Turbo of the Porsche doing all the work in shifting the intake air, I reasoned the response of the MAF would be much less acute.

This appears to be borne out as my SS cat, Autodelta headers and in particular the CB cams will create much higher flow velocities, sort of mimicking what a Turbo achieves. Cruise control is very smooth in the way it maintains the speed setting, with very fine interventions an economy is better than I hoped for, although unable to do further testing due to lockdown restrictions.

Yes, I do believe she is still a little rich, but she was on my last Dynamometer  run, with the same ECU. And I am impatient to try my Ascari back boxes again. However, “Slowly, slowly, catchee monkey”. There is plenty of mileage left in this project to keep me entertained for some time to come. And Although I set out principally to get engine temperatures down, I think I can say, I have ended up with a pretty quick motor. And yes, I still want to fit a Holden badge!

[bazzbazz]

And yes, I still want to fit a Holden badge!

THE HORROR! 

[specimenX]

Well the simple question is .. What is the part number of the MAF insert you had orginally prior to all the experiments?

[Craig_m67]

Well the simple question is .. What is the part number of the MAF insert you had orginally prior to all the experiments?

I am sure that Ascari32 is aware of the MAF that was originally installed in his vehicle.   If you read any of his posts, it will become apparent to you that he has made a number of modifications and is looking to improve upon what was spec'd by Alfa.

Might I suggest you start another thread for arguments, requesting if you want the five minute or full half an hour.