Engine dies out

[ForrestMelissa]

When we start are truck it starts then dies out changed just about everything any suggestions 

[ForrestMelissa]

It's a 2003 GMC Sierra 

[CamGTP]

May want to define what everything means, because we don't know what has and hasn't been done yet.

 

Could be a fueling issue or maybe even a security issue that is not allowing it to run.

[richard wysong]

What Cam said and maybe what engine

[dna9656]

Plugged catalytic converter or fuel filter, weak or about broken fuel pump, fuel pressure regulator, these are some of the most likely causes but what the other guys asked, we need to know what all you have done, any other symptoms related or not.

[Bleepster]

security issue?

[richard wysong]

HELLO??

[forrest deen]

Hello!I am Forrest from the ForrestMelissa post above.My truck is a 2003 gmc sierra 1500 4x4 5.3 liter. I have replaced the fuel pump, fuel filter , mass air flow sensor, air filter, throttle position sensor, map sensor, fuel pressure regulator, spark plugs, wires, all 8 coil packs, evap canister purge valve, crankshaft position sensor, and the pcm. The truck starts up first try when it is completely cold and it will idle fine until it reaches normal operating temp and the it sputters and stalls out and won't start up again until it is completely cold again. I am at a complete loss on this. I am no mechanic by any means, but I have had to learn as i go because I cant afford to put in a shop and I don't necessarily trust most shops anyway. If anybody has any ideas I would greatly appreciate some help. My truck has been down for 2 months now. I have had to borrow a vehicle for work. Any help would make a difference. Thanks!

[asilverblazer]

Sounds like it runs in 'open loop', but when it switches over to 'closed loop' where it is reading all the sensors to determine best operating parameters it stalls.

 

This indicates one of two things.

 

1. A sensor(s) is reading incorrectly and providing bad information to the PCM, which in turn makes incorrect adjustments and stalls the engine.

 

2. The PCM is getting good information from the sensor(s), components are not properly executing adjustments.

 

Best option is to find a good mechanic that can read all the operating parameters and results based on PCM adjustments. I would not expect a replacement PCM to be plug and play, and recommend returning to the original until a thorough diagnosis points to an actual PCM failure. 

 

Second best, check for any stored codes and report back.

 

Third, start physical trouble shooting. Once engine enters closed loop, try manually spraying fuel into the intake stream after the MAF sensor. Engine may try to continue running (probably poorly) pointing to a fueling issue. Confirm spark at the plugs. Confirm action of the throttle body and clean as needed. 

 

Since the engine runs in open loop, I'm ruling out any significant mechanical issues, but to be sure a compression check wouldn't be a bad idea. Other ideas to play with, throw a timing light on it, a vacuum gauge, and fuel pressure gauge.