2002 JTS 156 Engine Pinging

Started by DDALFA, February 28, 2012, 10:25:42 AM

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DDALFA

Guys,

Past 2-3 months irrespective of whichever brand fuel 98 octane i fill in, the engine ping's a lot between 2500 and 3500 rpm, dont feel drastic loss of power but i hate that pinging noise. Could it be cam shaft? or could it be MAF?.....as soon as i put my foot on throttle ....i hear pinging noise as if the valves are jumping.


Jekyll and Hyde


colcol

Hey DDALFA, it could be you have a faulty, knock sensor, i usually run Caltex 98 premium in my JTS, but a few years ago, i couldn't get any brand premium, due to strike\supply problems\refinery down\etc, and i used scungy 92 octane, and this was during the summer, and i do a bit of hill work, but no pinging, but the car seemed to lack a bit of torque, but you may get an alarm if the knock sensor is faulty, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

DDALFA

Bearing rattle  :-\ i would strike out that possibility ....cos the noice would continue once i leave the throttle. I am more leaned towards Colins view as i do notice a bit loss in torque ....especially while leaving clutch the revs just drops and i get a sort of jerk while getting the car off from stand still. dont know if thats typical alfa engine.

Regarding the alarm for faulty knock sensor .....havent received any warning. I have heard about JTS engines requiring change of camshaft .....i pray  its not that.

the car has done 110k also i go thorugh around 3 liters of oil between servicing (10k Kms).



Jekyll and Hyde

#4
Quote from: DDALFA on February 29, 2012, 09:26:17 AM
Bearing rattle  :-\ i would strike out that possibility ....cos the noice would continue once i leave the throttle.

Not if it's in the early stages....

Of course there are other possibilities, could be belts (particularly balance shaft) flapping under the right conditions, or balance shaft tensioner bouncing off it's stop, could be something on the exhaust rattling...  My point really was, just because it sounds like pinging, doesn't mean that it IS pinging....  Probably worth taking it to your local specialist for their thoughts, might save you some money in the long run.

Quote from: DDALFA on February 29, 2012, 09:26:17 AM
I have heard about JTS engines requiring change of camshaft .....i pray  its not that.

Fairly unlikely given the driving conditions required produce the noise.  Worn JTS camshafts usually tend to make the car sound like a diesel at idle and low revs...

Quote from: DDALFA on February 29, 2012, 09:26:17 AM
....especially while leaving clutch the revs just drops and i get a sort of jerk while getting the car off from stand still. dont know if thats typical alfa engine.

Sounds about normal for a manual 156 JTS - they normally do seem need a bit of a rev from a standing start...

colcol

If you needed a new camshaft, because of worn lobes, then it would be down on power, if it was a valve variator, then it sounds like a diesel at startup and idle, and i only noticed a lack of torque when using rubbish 92 octane, no name petrol, i hear that the knock sensor is like a piezo microphone, and picks up the sound of the pinging and the engine computer retards the ignition, some knock sensors pick up vibration, pinging is very dangerous, it is uncontrolled ignition, the firing can happen of the glow of the sparkplugs or any carbon glowing on the cylinder head, it will break your piston rings, which will scratch your bore and leak compression past the rings, i know it happened to me with my 1st car, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

DDALFA

COlin,

your description of pinging sounds scary .....the sound that i get is like a rattle ...checked exhaust ....definitely not comming from there .....what it feels like is the valves are jumping on their seat . expecially when i travel through citylink and if there is a wall next to road ...it sounds horrible.

L4OMEO

I'd be getting a specialist to check this out pretty damn quickly. If there's any possibility that the problem is serious then don't dick around.

No disrespect at all to the people who have given help so far, but diagnosis over the internet is not the answer if there's any possibility you're causing further damage while considering the range of possibilities that's been suggested.

Hope you get it sorted.

Cheers
Rory
2002 156 GTA

colcol

DD, what sort of fuel are you running in it?, when i have run cheap fuel, it is down on performance, pinging is a noise that sounds like marbels rattling around in a tin, you hear it when labouring car, such as chugging up hill or 5th gear at 40kph, my first car was a shocker for pinging, can pick up pinging on cars just driving past me, on a JTS, they sometimes suffer from carbon build up in the head, this can leave deposits that will glow and cause the air \ petrol mixture to fire at the wrong time, also the deposits can actually make your compression ratio go higher due to a smaller combustion area, have it checked without delay, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

DDALFA

#9
Colin, I switched to BP ultimate long time ago from shell power, never used other than 98 octane. Yes it does sounds like marbles in the tin can. and i have read about the carbon builtup...... in my next service i am getting the cam belts replaced (its due).......i will speak with Bruno (@ Marnello). some time ago i did speak to him about the Wynns's engine treatment .....but he warned me about it as it may cause damage to the throttle body.

http://www.wynns.net/wynns_psp_fuel.aspx


i may also get my brakes done (all 4 roters + pads) any suggestions.

FYI Rory,
the internet forum has been very helpful in previous occasions and i have always left feedback of what the problem was and how it was fixed. Last time i have problem with 4th gear popping out ...went to specialists and was told that there was problem with syncro ($2.5k quote) ...the forum helped me with pinpointing the problem and suggested the common swarf problem and the locating pin issue. went with the suggestions to another trusted ALFA specialist ...was happy to follow suggetions....for $200 the problem was fixed. thats saving of >$2k.

another time had a rattling noice underneath the engine.....went around to get it fixed.....every one scared me that its a CAT cone (very expensive).... following the suggestions from this forum, the guys were spot on. it was the connecting plate between the engine and exhaust ...cracked....fixed for $80.

I will leave it to you to do the sums.

Cheers!







L4OMEO

Hi DDALFA

Agreed, this forum community is extremely helpful and there's a wealth of combined experience and knowledge that people are willing to share. I've benefited from it many times myself, and it's a great way to either get some initial direction on a problem or as a second opinion to counter-balance any information you get from a mechanic that doesn't ring true.

That notwithstanding, I still stand by my comments in my last post. If the symptoms as described don't provide a clear answer; if there's more than one possible cause mooted; if it's something that really needs first-hand observation to fairly assess and test the symptoms; ultimately I think you should seek out a specialist (sooner rather than if there's any chance of ongoing damage, as, arguably, there was in this case). Having canvassed opinions through this thread you should at least have some possible causes to discuss with whomever you take it to.

Keep us posted on how this goes, hope it's a simple fix.

Cheers
Rory

2002 156 GTA

MD

Quotehe engine ping's a lot between 2500 and 3500 rpm

If this is correct and it is as bad as you say, I wouldn't even be driving it to a workshop, I would be trucking it in. Seriously, pinging engines put holes in pistons and that is what Rory is trying to subtly tell you. It's happened to an 8 month old  Fiat 1500 I had.Put a 12mm hole in number two piston and Mahle pistons ain't cheap. Not to mention the engine rebuild.

Fuel mixture and timing checks are an everyday job for qualified mechanics and a report about this problem should present no complex or costly information. The fix may be a different story which you might care to reasearch later once it is correctly diagnosed.

I think you are selling Rory advice short.
Transaxle Alfas Haul More Arse.

Current Fleet
Alfetta GTV6 3.0
Alfetta GTV Twin Spark supercharged racer
75 1.8L supercharged racer

Past Fleet
Alfa GT 3.2V6
Alfetta GTV 2.0
Giulia Super 2.0
Berlina 2.0

colcol

Regarding brake replacements, i bought some non genuine Italian rotors and Euro made Magnetti Marelli brake pads locally, and they seem to work ok, apart from the dust, next time will try something different, most likely Genuine Alfa Romeo from EB Spares, England, Colin.
1974 VW Passat [ist car] 1984 Alfa 33TI [daily driver] 2002 Alfa 156 JTS [daily driver]

DDALFA

Certainly Roary i will post an update on the problem. As i said, i am going to put in for the major service soon.

"I think you are selling Rory advice short."

Wow! good to see a queenslander backing up anothe one (AROCA: Queensland division), ;D,,,i gues guys u have all the alfa specialist there very genuine ...unlike us here ...some ave very genuine and some are ........


cheers guys!

MD

Hahha. Rory owes me five bucks for that but he doesnn't know the invoice is coming. :)
No, the support is not personality or locality based at all. I just happen to agree with the facts and wanted to make a strong point for you act with care.

Anyone who calls a spade a spade is alright by me. Best of luck with the choice of workshops.
Transaxle Alfas Haul More Arse.

Current Fleet
Alfetta GTV6 3.0
Alfetta GTV Twin Spark supercharged racer
75 1.8L supercharged racer

Past Fleet
Alfa GT 3.2V6
Alfetta GTV 2.0
Giulia Super 2.0
Berlina 2.0