redrider105

I have a 2005 GMC sierra it has a procharger with a custom dyno tune.
every time the battery is disconnected the truck has major idle problems. i understand that the truck usually search for idle but it is searching from 200-1100 rpm and will some times stall out. it has done this before and after a few days of driving it finally fixes itself. tuner says nothing is wrong. please help

AndysC3

iTrader: (14)

when the battery is disconnected all of the fuel trims are reset. after about 500 miles the pcm will "learn" what it wants to be at. it could be helped out in the tune. Its a good bit of logs and tuning but will work.

redrider105

i figured it was something like that but its just aggravating to drive when its stalling out. why is it such a wide range

oakley6575

iTrader: (5)

Sounds like your base idle airflow wasn't tuned for all your modifications. Like Andy said, the fuel trims are reset when the battery is disconnected. But along with fuel trims, the idle trims are reset as well. That means it has to reference your untuned idle airflow table which is way off. After some driving time, the pcm will learn how much airflow is needed at idle in drive and park. Your idle trims will add/subtract airflow from your base running airflow table to keep the idle rpm stable. Find a different tuner because it is very easily fixed.

redrider105

ha ha ok yeah every time i take it to him it stops the day before my appointment so he just says everything looks good. thank you for the information.

oakley6575

iTrader: (5)

Tell him to log the idle trims in park and drive and I bet they are pegged.