Really not a big deal but during cold start warmup routine, the motor does a hiccup or very brief stumble. Then just continues to warmup and idle down. Somewhere between 8C and 14C.
Is it a transitioning issue, IAC? It's in O/L obviously.

 

Anybody?

 

hi there my car is doing the same thing and i'm putting new plugs and wires on it I just put the longtubes headers on it and now running like crap at idle ill let you know if it works I just put spark plugs in it like 3 weeks ago so time for wires now

 

Not much to go on. If you think it may be the IAC get a data log. Look at that point and see if the IAC is dropping low, then at the stumble suddenly jumping higher to maintain RPM.

Does the stumble occur during the warmup/drive time? Or is it right after start up? The difference will be which AFR table to tweak to see if it is a lean issue.

RBob.

 

Bob,

It happens only in cold start and in the lower temps I pointed out earlier. It's a momentary hiccup and perhaps it needs to be a bit more gradual change in the IAC steps. It drops and stumbles once, idle rises back and then pretty much continues on its warmup routine. I have my WB hooked up so it doesn't appear to be lean spot in the O/L AFR v CTS table. I have also wondered if it might coincide w the Added cranking fuel timing out. However, it is one of those things you try tuning just because you can as opposed to it being a real issue. Warm start is not an issue.