I've searched several threads for a solution and have come up empty so far. 94 LT1 A4, starts fine, idles fine, hesitates, spits and sputters bad on acceleration if engine is cold (never dies). Sometimes has what sounds like a small "backfire" under the hood.

If I start the car and let the engine warm up 5-10 minutes it runs fine with only a slight hesitation on acceleration. I've changed plugs, plug wires, and fuel filter with no improvement. Have not checked fuel pressure yet, but will this weekend. Friend ran a scan on it and it wasn't showing any codes.

Anybody experienced these symptoms? I first thought opti, but figured it would get worse as it got warm or go out all together. Next I'm thinking clogged fuel injector or fuel pump going out.

Any ideas? Thanks, Mike

 

Have you checked the coolant temp sensor in the water pump housing for accuracy? If its not telling the PCM the engine is cold, its going to run lean until it heats up.

 

No, I didn't even think of that. I'll check it this weekend and go from there.

Thanks, Mike

 

I'm still having this problem after changing out the opti and coolant temp sensor.I checked the fuel pressure and it is good.

I don't know what to do next. Can someone point me in a direction I could be overlooking?

Mike

 

anybody?

 

what plugs are you running?

 

NGK tr55

 

those are the stock heat range correct?

 

yes