2.5 misfire when engine cold. - Alfa Romeo Forum
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(Post Link) post #1 of 2 Old 07-11-09 Thread Starter
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2.5 misfire when engine cold.

I fought that problem on my 2.0 TS almost 3 months, now i have my V6 after full engine rebuild, with the same problem - when started from cold, idles fine, but if i hit the throttle little bit too sharply, detonations from intakes begin. Must rev high to be able to pull from first gear, misfire and detonations again.....new NGK sp. plugs, new O2, new MAF, tested all hoses after MAF for leaks....when engine's warm - no problems......
Engine is CF2 type, originally with 2 sensors on the thermostat - one for ECU, and other for fans - but wire loom is for engine with only one sensor -3 pinned type sensor, no plug for other one. It's new too, when i compare temp readings via Alfadiag when start from cold, it match the approx ambient temp, and it rising normally.
Any other things that i may miss?????

Rear Wheel Drive Mid - Engined Alfa 156 3.0 V6 '99 - trackday car
Alfa 156 2.0 TS '00 - daily car

Fiat Coupe 20VTurbo, GT2860RS,
water-meth injection 120cc, custom manifold, 3" Downpipe, FMIC - entertainment car

Last edited by Speedmaster; 07-11-09 at 20:40.
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did you find out what was causing this? I have the same problem on my 156, see that you changed the MAF but still had the same problems afterwards?

I've found doing the reset cures my MAF problems (inc the pops from the engine bay) but after a few hours it returns to normal so don't want to spend out on a MAF if it's potentially something else.

It almost seems like the air being sucked in, is blowing back out, and causing the "pops" - and after putting a noisier filter on today, I'd think this is whats happening as the "pops" have now taken on the tone/loudness of the new air filter? lol

*edit* just reading - could this be related to the EGR valve?

Last edited by Dreamz; 10-12-09 at 17:09.
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