Did a search, but nothing like this came out. When I start a car, afer it has been sitting overnight, I get hesitation on all revs and it backfires, when I try to accelerate. After it has been warmed up, everything is perfect, no problems at all.

Seems llike this is something related to closed/open loop mode, but can't think what it could be ?

Any suggestions are appreciated, thanks !

 

Try resetting your PCM by unplugging the fuse for a while, could just be something in your tables that the car doesnt like that you car think it has "learned" over time.

 

Tried that, didn't help.

I noticed, that problem occures only when car is sitting overnight, not during the day, even when car is not driven for 4-5 hours.

Any other suggestions ?

 

Perhaps moisture in the distributor? Sitting all night and then acting up in the morning but never later on in the day leaves me to believe this. Maybe I'm wrong.