I have a cold start engine miss that is eluding me. It lasts 30-90 sec. Started about 2 months ago. Otherwise, no detectable issues.

2001 Grand Caravan 3.3 Flex

Here is what I have checked and/or replaced:The Snap-on is showing multiple cyl misfire, evap leak (which has been there well before this problem), and catalyst failure.

The live data shows map 19-20Hg, tps .67, st fuel trim -15% to -10% and upstream O2 running high during rough idle.

Fuel economy is a little below normal.

I am guessing something is going bad, but I do not want to throw parts at it. Any ideas?

All I've got is a lazy sensor (O2 or Map), or lazy part (injector or iac).

The rough idle lasts as long as closed loop should kick in, but I don't know if that is coincidence or not. Maybe a part that needs to warm up a bit to work.

I'm stumped.

 

I had this problem with my 03 3.8L GC. I treated the fuel injectors via vacuum hose with SEAFOAM. I was amazed at how much smoother engine is running now. And before it would stall out from idle, now idle is a lot smoother. Any engine with 100K + miles is going to have carbon build up.