My 09 Tahoe hybrid has been having stalling, lurching and cylinder 7 misfires recently.



Rides very rough especially when idle or in reverse. Seems to be when the two mode is trying to shut down four cylinders or switching to hybrid mode. Also there is oil leaking out like crazy from underneath around the aux trans pump. the fuel pressure will go up and down while driving (I occasionally smell burning oil not gas.-if you can see the aux pump it seems to be leaking engine oil and it smells like engine oil and the mechanic said it was indeed.Mechanics flat out tell me to go to the dealers except my buddies who are literally doing the research I am.



I can’t accept taking it to a dealer who will just redo all the **** I did above and charge me 10K. I am an orthopedic surgeon and will repay the best help with free phone injury consultation for friends or family!!



(I am a weekend warrior but a NOOB to hybrids). All the below was done with a very competent mechanic...the THIRD ONE stumped by the problem. II own several cars and rent them on TURO so I am DETERMINED to get to the bottom of this.





Codes shown:



P0300



(P0307, P0430 & P0455 but not anymore all these went away )



says “service hybrid system” on dash.





Things we’ve tried:



-We checked the fuel injectors and they are in good shape.



-we did engine oil and trans oil changes



-we shifted the car into M and the same exact shuttering and sounds occurred when the hood was popped in auto stop.

No

. I placed the vehicle in park and attached two videos of the symptoms.



-cleaned out mass airflow sensor and replaced



-air filter change



-new 12V battery



-Changed all the spark plugs (yup went in behind the passenger wheel under the splash guard)



-changed the coils.



-replaced throttle position sensor and throttle and cleaned with electric cleaner



-used cataclean and laquer thinner on the cat through gas tank (like Scotty said) and that cleared the P0455 and P0430



-drove around with mechanic who had attached his 7k obd reader. He only saw misfires and said it’s communication between the hybrid trans and engine and its getting confused but he isn’t 100%.





Is it a matter of cleaning the corrosion on the hybrid battery?





is it the aux trans pump?





Please help!!!

 

Checked the fuel injectors? Fuel pressure? Did engine/transmission oil changes?
If you set the shifter to M and open the hood, does it still do the things you mentioned that happen when it is deactivating cylinders or going to Auto-stop mode? (Hood open will disable auto-stop)

The aux trans pump is at the front of the transmission oil pan.
Is the oil that is leaking transmission or engine oil? There is a gasket between the Aux Trans Pump and the transmission. Check that the bolts are torqued down properly.

 

Hi Jamie!

-fuel injectors in good shape
-fuel pressure is good
-haven’t tried the hood open auto stop but will tomorrow
-its leaking engine oil
-I will check the bolts by the gasket in the morning.
-

 

Hi Jaime!

sorry for the early am reply I am on call late hours at the hospital.

I own several cars and rent them on turo so I am DETERMINED to get to the bottom of this.

So after a week or two to be sure my observations were correct (I am a weekend warrior but a NOOB to hybrids). All the below was done with a very competent mechanic...the THIRD ONE stumped by the problem.

-We checked the fuel injectors and they are in good shape.
the fuel pressure will go up and down while driving (I assume you mean the gauge on the dash) but we noticed it is leaking engine oil and -I occasionally smell burning oil not gas.
we did oil and trans oil changes yes.
-I shifted the car into M and the same exact shuttering and sounds occurred. I placed the vehicle in park and attached two videos of the symptoms.

-if you can see the aux pump it seems to be leaking engine oil and it smells like engine oil and the mechanic said it was indeed.

no one else has responded. Mechanics flat out tell me to go to the dealers except my buddies who are literally doing the research I am.

 

The gauge on the dash is for the oil pressure. It should go up slightly at higher RPM, but you say it goes up and down. If it is fluctuating too much, maybe you have oil issues at the AFM solenoids? Have you replaced the oil pressure sensor and small filter screen under it? This filters the oil going to the lifters to activate/deactivate AFM mode. Check the screen to make sure it is not partially clogged.

Also, I came across this page: https://dannysengineportal.com/engin...-6-0l-engines/
Symptoms described there sound like what you are seeing. New Intake manifold gaskets would fix that.