Help...156 V6 2.5.... - Alfa Romeo Forum
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Help...156 V6 2.5....

Can anyone help...
My 156 V6 2.5 starts fine running on all 6...but then after a few minutes seems to develop a missfire... Revs still at around 1000 rpm as if cold all the time or compensating for something. When pulling away very hestitant...
I took her for a blast and the engine was hesitant (over the speed limit)...but I just pushed it passed and onwards ...seemed to have cleared the issue at high revs...but when at idle missfire comes back...
Any ideas...I have changed the MAF (had a spare) but no difference.
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Idle misfire could point towards Lambda sensor failure.
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When was the last time all six spark plugs were changed?

Bear in mind that many "lazy" mechanics and previous owners often neglect to change the rear bank below the plenum chamber because it's more "difficult and time consuming" getting to them in the first place
At least 40% of the V6's I have worked on in the past have had different makes or notably older plugs in the rear bank compared to the front, so what does that tell you?

Get the ODB codes read when the misfire occurs, if it comes back with nothing, something none specific or generic, then it's two options... Plugs and/or coil packs.

If in doubt and you can't be sure if the plugs were changed for definite with the mechanic showing you all six old ones, get them changed as a matter of course and maintenance so you effectively haven't wasted money. You can also check the coil packs and boots while performing the task in order to eliminate them.

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