Engine dropping in RPM and stalling

[dillpickle02]

I have a 2007 yukon XL denali and recently I've noticed after some driving and coming to a stop the engine will start to struggle with idle being around 500 and then sometimes dropping down to 400 and sometimes stalling, putting it into park or neutral brings it back to normal operating rpm, it will start instantly back up except for once when it took over 20 minutes, I noticed sometimes when I give it a lot of gas especially after it just stalled I can usually smell gas strongly, any help would be appreciated before I rip out the engine and transmission for a swap

 

[BG1988]

Royal purple fuel injector cleaner use at lest 2-3 cans

highly suspect oil refineries have been actively trying to sabotage our gas engines, by fouling up the injectors

What better place to do it at where no one would suspect


MPG has been nobly erratic across all my cars. many many others report the same thing. also check the oil for gas smell..i'm sure your mpg dropped as well...

I was able to restore the MPG on my toyota(26 around town) and tahoe Not the sonic though still the 1.4L 4 banger gets 20mpg(less then my tahoe hybrid 6.0l) before i could get 27-34 Hyw respectively.... it's 2018 with only 15k miles

 

[avalonandl]

Clean the throttle body also. There are threads on here.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

IMO, you do not have a major problem. As folks above have suggested, some minor cleaning maintenance is your next step.

 

[Meccanoble]

Definitely sounds like maintenance. As others suggested, start with the simple that would benefit you regardless if you had a problem or not. Fuel injector or complete fuel system cleaner. look into possibly cleaning throttle/MAF. I had similar issues on other cars and it was related to sensors, i believe camshaft/crankshaft. Do you have issues starting the car or only problem is when car is at idle? Do you see things worst when engine hot vs cold? If you do a high rev in Park, does car die when returning back to idle? Assuming no CEL, though you could search for hidden ones. Any change of gas recently?

 

[Fless]

Adding to the prior suggestions, with a load on the engine (in gear) a vacuum leak could negatively affect the idle, as well as cause the computer to call for more fuel. Might check your LT- and ST-fuel trims at idle, and at 1,500 rpm and post them up.

 

[swathdiver]

I have a 2007 yukon XL denali and recently I've noticed after some driving and coming to a stop the engine will start to struggle with idle being around 500 and then sometimes dropping down to 400 and sometimes stalling, putting it into park or neutral brings it back to normal operating rpm, it will start instantly back up except for once when it took over 20 minutes, I noticed sometimes when I give it a lot of gas especially after it just stalled I can usually smell gas strongly, any help would be appreciated before I rip out the engine and transmission for a swap

A scan tool would be great to help check for air and exhaust leaks. Walmart and auto parts stores sell a little 1 use kit to clean the throttle body and mass airflow sensor. Take the throttle body off of the intake and clean both sides of it and the edge of the plate and put it back on. Snug up the intake manifold as well, but not too much!

GM runs the idle low for emissions, tuners routinely raise this 50 to 100 rpms to keep the engine from stalling, especially if you lift off the gas quickly.

Some of those first year Denalis had trouble with vapor lock, the fuel line getting too hot and wrapping it seemed to solve the problem.

 

[Denalibro76]

A scan tool would be great to help check for air and exhaust leaks. Walmart and auto parts stores sell a little 1 use kit to clean the throttle body and mass airflow sensor. Take the throttle body off of the intake and clean both sides of it and the edge of the plate and put it back on. Snug up the intake manifold as well, but not too much!

GM runs the idle low for emissions, tuners routinely raise this 50 to 100 rpms to keep the engine from stalling, especially if you lift off the gas quickly.

Some of those first year Denalis had trouble with vapor lock, the fuel line getting too hot and wrapping it seemed to solve the problem.

Just had this exact issue happen to me tonight. Went to the store and on the way home it stalled when I let off the gas to come to a stop. Starts back up with no issues but seemed like it was struggling to idle normally.