thunderkitt3n

Hi, I swapped in a 5.3 into my 95 rcsb silverado and i'm having a hard time getting to idle in cold temps. i have changed a few things in the tune but for some reason it is still commanding 8.5 afr. I already disable flexfuel and that helped when its warmer out, but now that it is sub zero it wont stay running. it pops right off and runs with throttle but wont idle without throttle input. any help would be appreciated. its a stock 02 5.3 minus headers with the original pcm not pro tuned.

gametech

iTrader: (1)

Reflash a completely stock tune. It should run fine. Since it probably won't, then you start with the IAC and work your way through the hard parts that could have went bad. Don't try to out-tune a mechanical problem. You will be endlessly chasing your tail.

thunderkitt3n

I don't think I have a mechanical problem with anything, it all appears to be functioning correctly. I think it is in the tune/wiring because my 5.3 has never had the normal high idle that drops with the engine warming like it would in a factory truck. right now even its 30 degrees out once it starts the idle drops right down to 650 like a rock. I can go start my gto and it idle will hang up a bit until then engine warms up. I am thinking it may have to do with the motor coming out of an automatic trans and my truck is an manual, or maybe I need to hook up my vss for some reason? I don't have any DTC's or anything pointing to anything obvious. does anyone have an idea of what input I may be missing?

gametech

iTrader: (1)

VSS is referenced by numerous tables. You should definitely look into that. Also, there are many differences between auto and manual configurations, but only a few will cause problems.

thunderkitt3n

do you know how I can get my pcm to think that it is in a manual truck? I noticed the pcm thinks its in second or third gear when the truck is idling so i think that is why I don't have the normal idle charistics, and i think that is why is stalls in the cold weather.

gametech

iTrader: (1)

It appears you have EFI, while I have HPT, so I don't know if you have a "compare" feature you can use. If so, I would look at a manual tune, and change the tables that are relevant from the auto tune. If this does not fix the issue, there are also a couple of minor wiring differences that could cause problems between the two. It has been so long since I had to deal with this issue that I do not remember specifics.