156 2.5 v6 idling stutter? - Alfa Romeo Forum
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(Post Link) post #1 of 9 Old 15-11-09 Thread Starter
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Hmmm 156 2.5 v6 idling stutter?

I've just had a auxiliary belt disintegrate on me and fitted replacement with tensioners and pulleys. After some tinkering and getting the belt fitted correctly the natural progression was obviously to start it up.
It sat at idle for a while, whilst the new belt bedded onto the pulleys.
Heres the problem, when its sat at idle theres a judder almost like theres a mis-fire, however get it up to 1500-2k rpm the engine's as sweet as a nut?
All guages work as they should, there appears to be no fluid problems and its got plenty of oil in it!
Can anyone shed some light on it? I've been told it may be a head gasket failure (without the obvious signs), overheated spark plugs? Any help would be appreciated.
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Did any of the belt get under the cam cover into the cambelt drive when it disintegrated?

It may have made the cambelt slip a tooth.


Also try doing a throttle reset before worrying too much.
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Quote:
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It may have made the cambelt slip a tooth.
Probably not as my friend had this problem on GTA, cambelt sliped a tooth when he was hitting rev limiter and the car was showing ECU error. Diagnostic showed faulty camshaft position sensor. This was replaced and the error still came on. It took a month to find out the cambelt sliped 1 tooth because the engine was iddling just fine just above 2k rpm the error allways came back and put the engine into limp mode.

Check the aux belt tensioner, maybe its not tightened and is "jumping" in low revs.
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I'm goin to try a reset as soon as I can.

I've read a post (and bloody pitched in long after it had finished) about the exact problem, which turned out to be the lambda sensor. So reset first then I'll try lambda sensor. Tested emmissions for misfire and head gasket failure and it came up nowt.
Got to admit its got a deep rasp at low revs which I wouldn't mind keeping. Sings like Catherine Jenkins 1500rpm and above. Fuel consumption shi-ite!
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GTV V6

My V6 GTV is doing this as well, Mine seems to get worse the engine warms up, so could be air/fuel ratio?

Any thoughts?
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My V6 GTV is doing this as well, Mine seems to get worse the engine warms up, so could be air/fuel ratio?

Any thoughts?
Could be MAF, Lambda or coolant temp sensor.

Also check the air intake hose for leaks.
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I used the Alfadiag at the weekend and it's saying the number 2 lambda has an error.

Now all i have to do is figure which is number 2?
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I think there is one before and another after the CAT.

I would guess that number 2 is the one after the CAT.

One sure fire way to find which one it is is to find the connectors for the sensors and unplug them in turn. If after unplugging one of them you get Lambda sensor 1 error then you know you have unplugged the wrong one.
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Both pre cat on mine, as i understand it, lambda sensor 2 is (bank 2), which i think is the front head.
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