Idle timing surge and weird LTFT's in PE

[bmuir]

I have a couple of issues that you guys may be able to help with...

Truck is a 2001 with LQ4, Radix w/2.9, Headers, and Exhaust, MAF tune

When first starting up the truck doesn't want to stay running and the timing surges, you can see this in the first log file i've attached. If I start it with the pedal pressed slightly and keep the revs around 1000-1500 this doesn't happen

Also once warm, sitting idling it will randomly surge between 400-800 rpm and 36-0* of timing??? Is this a vacuum leak because my trims at idle seem off too, but cant kind a leak anywhere. You can see this in both the first and second log attached.

Final thing for now...when going into PE mode sometimes it will keep the trims at 0, and other times they go positive. It will happen all day one day, then the next day the trims are back to going positive. If the trims go positive the run at about 10.7 AFR mid throttle boost, and at 0 LTFT it will stay in the 11.4-11.5 area. It seems to be very random! Ideas on what may be doing this?

Thanks for the help!
-Brian

[joecar]

Hi Brian,

Might be indicating that idle airflow incorrect, seems to compensate with spark timing, have you tried this: Idle Tuning (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside).

Check for airleaks at intake manifold regardless.

[joecar]

When going PE, negative trims get rounded up to zero, positive trims are maintained and added to PE...

from day-to-day how much are the trims varying...?

[bmuir]

usually when positive they are 4-7 or so.

[bmuir]

Hi Brian,

Might be indicating that idle airflow incorrect, seems to compensate with spark timing, have you tried this: Idle Tuning (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside).

Check for airleaks at intake manifold regardless.


thanks joecar, ill try the idle tuning and see if i can get things sorted out.