WILL NOT IDLE WHEN STARTING COLD

[Huntintruck]

2000 GMC TRUCK SIERRA 1500 4WD

8 Cylinders 294 V 4.8L SFI

 

WILL NOT HOLD IDLE UNTIL IT WARMS UP

 

Truck seems to run fine, but check engine light is on. My mechanic checked for codes, but said there were no codes and turned the light off. I have had no problems cranking, until the last few mornings have been below 45 or maybe 40 degrees. The engine cranks, but goes dead. I give it some peddle, and it runs, but goes dead immediately when I let off the peddle. I can hold the peddle for a minute or so, and it warms up enough to run normal, and the check engine light goes off. It comes back on within a few miles. This morning was warmer, about 60 degrees, and it started and idled perfectly. I am going to check the codes again, but just wanted to see if you had any ideas.

 

Thanks!

[GM-Tech]

  My mechanic checked for codes, but said there were no codes and turned the light off. 

 

You need to find a new mechanic. The only way to turn the light off is by clearing the codes that are present.

 

Could be a lot of things. Fuel pressure regulator leaking, IAC not working properly, etc., etc. Knowing the code(s) may help.

[Huntintruck]

He just starts replacing parts untill the problem is eliminated. But the other mechanics here do the same thing. I always seem to have to replace several parts before the real problem is revealed. But they are good at fixing things after I diagnose the problem.

I thought that was strange that the check engine light would come on without a code. I'll try somewhere else.

 

Thanks!

[GM-Tech]

He just starts replacing parts untill the problem is eliminated.

 

YIKES! That's an awful expensive way to diagnose something.