Hey guys - just ran into a very bizarre issue. All of a sudden my 2009 Yukon Hybrid started giving me a very high idle when coming to a stop, at a stop, and in park ~1500 - 2000rpm. It doesn't go into auto stop mode it just stays high revving until i start moving, then gets jerky with the shifting because it's at such a high idle. Once i'm cruising though, it's fine.

any thoughts? The only thing that was abnormal was i was my gas tank was close to empty, probably 1/16 tank left.

 

I would start with cleaning the throttle body, checking the wiring plugs on it and also the Mass air sensor. Also check PVC line or anything that could be an air leak into the intake.

 

I also would say dirty throttle body or most likely mass air sensor. Especially if you have an aftermarket K&N style "oiled" filter. although K&N filters are very good, they have a tendency to let oil mist accumulate on the mass air sensor & throttle body.

 

thanks for the tips. The throttle body is as clean as can be, it was fully cleaned when i replaced all the plugs and wires about 5K ago. The air filter is brand new and stock, so no K&N oily mess. No vacuum leaks as far as i can tell. I sprayed all the usual suspects with some carb cleaner and no surge. Also checked all the fittings and everything is tight.

This only happened when i was low on gas and hasn't happened since. I'm thinking it's related to low gas (i have no idea how) OR maybe i need a new 12V battery. I know hybrids do some funky things when the battery is going out.

I have yet to get the gas level low enough to try and replicate the problem. I have an extra battery laying around and i already swapped it. If i can get it to happen again, i'll let you all know what i find out. But, i'd be happy if it didn't happen again.

 

My hybrid drove smoothly until the last drop of gas. I only noticed when all the lights popped up.