Can't nail startup RAF
 

Maybe I'm going about it the wrong way.

My long term idle trims are pretty close to 0% and my short term idle trims look good except for startups...especially hot re-starts.

My short term idle trims are in the +2 g/sec at hot restart even though my LTIT are low. What affects this more? Idle Airflow Parked Position {B4308}? Startup idle airflow correction {B4303}? Startup Friction Airflow Correction {B4343}? FWIW, my values are raised above stock for B4308 and B4303.

Does the positive number mean I'm not getting enough airflow and the PCM is needing to add more? Thanks in advance.

b4303 solved my problems with starts if it lasts for 21 seconds it most likely this table

Hmm... I am assuming you are refering to B4343 and not B4303.

It could be that your hot start enrichment tables are making you run way too rich and bogging so your iac has to make up for it to keep your engine running.

Mine does the same thing. The value is coming from the Startup Friction Airflow Correction {B4343} table. As soon as this value zeros out it is transferred to the short term idle trim in drive and park/neutral. Leaving the car in park it takes the short term idle trim about 30s to return to “normal”. When I put the car in drive the IAC numbers and idle jump up responding to the high number in the short term idle trim and within 30s the short term idle trim return to “normal”. All is good until I turn the car off and restart it.


John

Have you tried adjusting the decay and delay rates for the Friction Airflow Correction? I changed mine and this seemed to help on both hot and cold start ups.

I have played with the decay rate. The issue is after the Friction Airflow Correction value has decayed to zero the original Friction Airflow Correction value is placed in short term idle trim for drive and P/N.