Check your BISS and Idle Speed Control Valve settings.. I did see your symptoms on another car that couldn't find a good idle speed either because of an out of range MAF reading, or his BISS was set so high that the ISCV couldn't adjust the speed to its target.

 

what is BISS?

 

Basic Idle Set Screw.

 

Back from the dead! Why is this???

 

He stated that before many tables in the ECU that contributed to this where found.

 

Thanks for the lightning fast reply. So why would a good tuner not be able to tune this out (the car has some go fast parts including Kelford 272s, BBK but stock ECU)?

 

Something wrong with the car or not really a good tuner?

One thing to keep in mind is that the cold start stuff is the hardest stuff for a tuner to get right if he doesn't own the car. You only get 1-2 shots at it per day and every car is going to be different.

Once it's started, even if it's shut down quickly, there is still heat and fuel in the cylinders that wasn't there before you started it the first time in the morning.

So I wouldn't be too harsh that a tuner didn't get it perfect after one tuning session.

 

Well known tuner, I'll keep names out of it. There was a compression issue that is now resolved. How would I verify if it's in closed or open loop? One thing's for sure, it's ridiculously rich on cold start.

 

That is likely due to an injector scaling/latency issue... the car starts and runs in open loop for a few seconds before transitioning into closed loop

 

Once water temp hits the lower hash mark, it smoothes out a lot. If I drive before that, it drives like it popped a coupler and bucks.
Part throttle when idling is required when cold as well.
Drives good when warm.

 

holy old thread!

Not sure what I did to fix this problem, as it was so long ago, but it doesn't happen anymore. Maybe do a boost leak test and/or check that your BISS is adjusted correctly.

 

^^ I'll be at Thunderbolt with you in a few weeks and you can see the problem for yourself, unless the tuner can fix it before then. Boost leak is good / compression is good.

 

Sounds good! I will have my computer & stuff with me, so we can check your settings against mine. Who is your tuner?