Trouble with stalling when coming to a stop, '06 Denali

[FergL]

So I have tried to Google the hell out of this and still cant find a definitive answer. I have a 2006 Denali XL with approximately 220k on it. When the outdoor temperature gets higher ( 70-100f) the truck will slowly stall itself out when coming to a stop at a light. I will turn off the truck for a few seconds, and most times it will fire back up and be able to drive again. Next stop light, same thing.

I have experienced this with the fuel level at a 1/4 tank and at 3/4 tank. I have no codes that come from this occurrence either. Usually once I have made it home, the truck sits overnight and will act as if nothing happened the next day. I have driven 3 hours straight with the cruise control on and suffered no ill effects.

I had the intake gaskets done about three months ago and have kept regular oil changes going through the truck. Is this a crankshaft position sensor, or a fuel pump? I'm hoping it's not fuel pump due to the labour required to change it. Any guidance would be appreciated.

 

[PNWYukon]

Wow. No codes at all?? Do you have a way to run live data? It only does it when the outside temperature is high, but engine temperature is cold?

Be good to know what the fuel pressure looks like from driving to a stop.

Did this begin after the intake gaskets were done???

 

[TollKeeper]

Almost sounds like the MAF is reading wrong, or stuck. Got a buddy you could borrow one from?

Other than that, live data would be the only way to see whats going on. LTFT, STFT, Miss Count, Temp Range (either air flow, or maybe CTS).. But all these should be throwing codes. And thats the confusing part.

If you throw the truck into neutral, and 2 foot it (one on the gas, and one on the brake), can you feather the gas, and keep it running?

 

[FergL]

Wow. No codes at all?? Do you have a way to run live data? It only does it when the outside temperature is high, but engine temperature is cold?

Be good to know what the fuel pressure looks like from driving to a stop.

Did this begin after the intake gaskets were done???

No, I still have an existing code for the evap system for the charcoal canister but I wouldn't think that would cause the issue? I don't have any way to get live data.
I should've clarified, ambient temperature is hot as well as a fully warmed up truck. Does not occur when the truck is cold. It happened once last year when the temperature was about 108 f ( 42 c). It was an exceptionally hot day for this part of Western Canada. Truck was good all through winter, and had the gaskets done in February.

 

[FergL]

Almost sounds like the MAF is reading wrong, or stuck. Got a buddy you could borrow one from?

Other than that, live data would be the only way to see whats going on. LTFT, STFT, Miss Count, Temp Range (either air flow, or maybe CTS).. But all these should be throwing codes. And thats the confusing part.

If you throw the truck into neutral, and 2 foot it (one on the gas, and one on the brake), can you feather the gas, and keep it running?

I may be able to source another MAF to try out. I did try putting the truck into neutral at the light, and even with feathering the throttle pretty good, it would not stay running.

 

[PNWYukon]

Here is someone's solution from another forum:

On one vehicle I owned I did have a similar problem where it would suddenly die, then after waiting a few minutes I could start it up again. There were no engine codes, nothing. It took me a long time to troubleshoot it. Eventually I found some info online where someone suggested checking the Crankshaft Position Sensor. I think I took a reading with my my ohm meter on it and it was out of spec. After replacing this sensor the car never had that problem again.

 

[FergL]

Here is someone's solution from another forum:

On one vehicle I owned I did have a similar problem where it would suddenly die, then after waiting a few minutes I could start it up again. There were no engine codes, nothing. It took me a long time to troubleshoot it. Eventually I found some info online where someone suggested checking the Crankshaft Position Sensor. I think I took a reading with my my ohm meter on it and it was out of spec. After replacing this sensor the car never had that problem again.

That's sort of what I'm leaning to, and thankfully isn't a very tough fix both part wise and labour. Appreciate the input!!!

 

[ks03]

No, I still have an existing code for the evap system for the charcoal canister but I wouldn't think that would cause the issue? I don't have any way to get live data.
I should've clarified, ambient temperature is hot as well as a fully warmed up truck. Does not occur when the truck is cold. It happened once last year when the temperature was about 108 f ( 42 c). It was an exceptionally hot day for this part of Western Canada. Truck was good all through winter, and had the gaskets done in February.

What code?
A wide open purge valve on a hot day with a hot engine at idle could cause a stall. So if the code was evap flow during non purge, or just a purge valve code, that could do it. If you have a leak or vent code, more likely not.

 

[fasteddy]

Does it do it if your A/C is off?
Another member was plagued by this issue of "near stalling"

It was the clutch going back on his A/C compressor and placing too much load on an idling engine.
and his A/C would go warm at idle as well.