2001 LQ4 Tune

[slowgto001]

Can someone look at this tune and log file? This truck is impossible to cold start. I know the MAF is set to 0 as it's in Speed Density mode (due to a wiring issue with the MAF). When you unplug the IAC the truck wil start and run if you plug the IAC in while the truck is running the idle will smooth out and it will even go as far as recoving when you rev it (IAC count is also sub 100). However shut the truck off and try to start it again (even immediately when warm) and it just will not. It fires and immediately dies.

2001 LQ4 Swap
Custom harness
408 CI Texas Speed stroker motor
102MM FAST inake

Below is the current tune and log file. You can see when the disconnected the IAC and it started. Then when the IAC was plugged in the idle smoothed out. To make things worse the truck is 3,000 miles from me so everything is having to be relayed and one tuner already took a (mail order) crack at it.

[5FDP]

The IAT sensor is having problems too, when it start it up it thinks it's -38 degrees outside then it starts working way later on in the log.

Have you messed with the idle air tables and any cranking VE to make sure it has fuel on start ups?

[slowgto001]

The IAT sensor is having problems too, when it start it up it thinks it's -38 degrees outside then it starts working way later on in the log.

Have you messed with the idle air tables and any cranking VE to make sure it has fuel on start ups?

Yes, referenced a stock file and adjusted in the ballpark of what a big cam should be. That's probably when the MAF got plugged back in trying to see if that was the issue. I zeroed out the IAC part correction just to make sure that was not messing with it as well. I appreciate any and all insite on this as I am starting to eliminate things one at a time to find the culperate.

[dermotw]

Try changing the friction airflow INITIAL (not startup). My own experience of these is that they operate "the other way around" (or so it appears, I asked about that, no-one ever answered..). INITIAL makes all the difference to startup & a few secs (typically) after, but STARTUP is only very short/while cranking. By tweaking the decay you can control how it drops back to normal.

[85K5Jake]

Your IAT sensor or wiring is bad my dude. it goes from -38 degrees to 115 degrees in less than 1 second. I would start there. if the ecm thinks its -38 degrees you are going to get a shit ton of fuel and flood the motor, thats why you have to hold the throttle open to get it to idle. As soon as you hit the key to start the engine its most likely already washing the cylinders and plugs with too much fuel. with your map reading and the -38 degree IAT your commanded AFR in the tune you are running is 8.83 at startup you should be around 13.0 to 13.5 working up to 14.7 as the truck warms up. Also your base idle airflow is too high with a cam your will require less RAF at idle. heres my tune if you would like to check it out and compare tables.