2001 6.0L Trouble starting during cold weather

[Black Dog]

Hello everyone. Need some help on diagnosing a starting issue on my 2001 2500 Silverado 6.0L. There are 257,000 miles on the truck. The truck runs great and starts with no problems until the temperature drops. I notice it starts to become problematic around 20F and gets worse the colder it gets and eventually will not start well below zero (around -15F)

The battery is good and turns over just fine. When the truck has sat in cold weather overnight or around 8+ hours it will start immediately and idle at 1000 rpm for a few seconds. Then it will begin to run rough and eventually die. I will restart and it will start and do the same thing. After third or fourth start it will idle at 1000 rpm begin to run rough and then clear up and run just fine.

At 20F it will start idle at 1000 rpm, run rough, and then clear and run fine. The rough idle and stall come at colder temps.

I changed all plugs, wires, fuel pressure reg., and fuel filter. Cleaned and tested MAF.

There are no warning lights or codes being thrown. Could it be IAT sensor? TPS?

I use heat lamps aimed at the motor at night and that seems to help some but it still does the same thing. Just not as bad.

Any thoughts?

Thanks, Rich.

 

[zora]

Assuming you have no check engine light on, it might be related to IAT or engine temperature sensor. Have you tried cleaning the throttle body and the IAC ?

 

[Black Dog]

I have not tried cleaning the throttle body or IAT. I think I will tackle that next. Would a bad IAT throw a code? or not always? Thanks for the suggestion.

 

[zora]

I meant cleaning the IAC, idle air control not IAT, intake air temperature. The IAC can get carbon deposits that will not throw a code.