Wt99C5

binksZ06, I have a nasty cold start problem. She runs up to 2.5K rpm's then slowly idles down. I do have a p&p maf and t.b. should I try going back to stock or is this strickly a tuning problem ?

Bink

*I have zero experience with ported MAFs. But, basically you are increasing airflow so you should be able to correct it .Do the RPMs decrease as it warms up and migrates toward operating temp?? If it does it probably can be corrected with the IAC table. LS1Eit--> Eng Cal -> Idle and Limiters Tab -> IAC Park Postion Table. IAC Park controls the amount of air entering the engine at idle. It controls the Throttle Blade Position at idle in ETC cars .


*Scan it and see what temp ( Engine Coolant Temp *C) and TPS% ( Throttle Position Sensor Percent) values are - as it's revving to 2500 RPMs.


*You may be able to make SMALL adjustments to the IAC at the RPMs effected - and correct the airflow problem. Small being reducing by 1.0 - 0.5 units at a time. 5 IAC units = 1% throttle position.

* So, if it's happening at 40*C and your IAC is stock at 19.00 then try 18.00. Let it cool below 40*c and rescan. I'd note your initial TPS% and see how much you pull it down and by how many RPMs. Go proportionately from there.

*If that doesn't help I'd go to stock a MAF. Ported TB is adjusted, easily wth the IAC Park Position Table.


Good Luck. :thumbs: :flag

Wt99C5

Thank You,,, my guess is I'm making too large of changes to the IAC table. To the garage, :rofl:

Bink

Yes...I always have the tendecy towards "more is Better". At 19.0 that's a TPS% of around 5% ( there is a 1% base TP% onto which IAC is added -at least on my car there is). Little changes have great effect.
If your engine starts to surge as the RPM comes down then you will also need to adjust Idle Air. Same tab as IAC Park - right below IAC Park is Idle Air.
Idle air needs to be adjusted in tandem with IAC Park. Idle Air is also called "Running AirFlow" on top of the table. Adjust this .05 - .1 at the temps your adjusting IAC at. Hopefully your using Edit v1.3 - prior versions the table is incorectly scaled. As an example - I recently increased my IAC Park by 5.0 pts and increased my Idle air 0.5 pts. Initially I bumped it by one...too much, so I backed down 0.5... it figures. :lol:
To really tell how it's doing you should do an Idle Relearn after each adjustment and give it awhile to learn. It's tedious work. Good Luck.