5.3 litre stalls after startup

[William Bouma]

My 2001 gmc yukon 5.3L almost stalls (and sometimes does) when the outside temp is below 5 degrees celcius (41 F). It always starts fine, but then starts stalling after about 10 seconds. The fuel pump has been replaced and it didn't help. I don't want to sink any more money into this car.

 

[retiredsparky]

Can you buy a code reader to see if it has any engine related codes? I assume you can't drive it to a parts store to get the codes read.

 

[dantheman]

does it stall if you are applying throttle to it or just idling? whats the idle RPM? electric or cable throttle?

 

[YukonandtheHOE]

Sounds like the MAF is going bad, it has the IAT sensor in it aswell. Gen3's wont run without MAF and IAT communicating with the MAP

 

[rockola1971]

Say what? Maf, IAT and MAP give a feedback signal to the PCM. I know the OBS had common voltage feeds to some of the sensors but they also still gave a feedback signal to the PCM only.

 

[SnowDrifter]

Do you have any codes?

 

[YukonandtheHOE]

Say what? Maf, IAT and MAP give a feedback signal to the PCM. I know the OBS had common voltage feeds to some of the sensors but they also still gave a feedback signal to the PCM only.

5.3's wont run with the maf unplugged, 5.7's will..

 

[rockola1971]

5.3's wont run with the maf unplugged, 5.7's will..

"Gen3's wont run without MAF and IAT communicating with the MAP"

And a sensor doesnt comminicate with anything. It simply provides a one way signal to the PCM which the PCM uses as information to make a decision. Communication would mean two way and that doesnt happen in the case of the IAT, MAP and MAF.

 

[YukonandtheHOE]

"Gen3's wont run without MAF and IAT communicating with the MAP"

And a sensor doesnt comminicate with anything. It simply provides a one way signal to the PCM which the PCM uses as information to make a decision. Communication would mean two way and that doesnt happen in the case of the IAT, MAP and MAF.

Absolutely correct..

Using reference voltage to the ECM it needs to have Air Volume+Air Density+Barometric pressure data for the ecm to calculate Volumetric Efficiency and Lambda for the fuel trim and spark tables.. Unless your running a 2bar Os in speed density mode, reminiscent of the obs 5.7 that will run closed loop with out the maf. The whole reason i brougt it up was he mentioned Ambient air temp was apart of his issue..

 

[rockola1971]

An older trick for the older fuel injection systems was to give the MAF a good tap with screwdriver handle. If the engine stumbles then comes out of it then its good. If the engine dies then the MAF is bad.

But......

Its his intake manifold gasket causing all the fuss. It needs replaced. My 2003 5.3L did the same exact thing when the ambient temp was around 39 or 40 and below. Intake manifold gasked replaced fixed it. Simply spray some starting fluid, etc around the mating surface of the intake to the heads with engine running and when you find the leak the RPM will jump up.