Cam Sensor Problems....STILL

[H32NV]

So Ive been having an issue with rough idle, and reduced power, and have thrown a few codes here and there for high idle rpms, cam sensor bank A malfunction, cylinder 1 misfire...etc. I took it to the dealership back in September '11 because I am at 83k of my 100k warranty, and they told me that sensor components on the engine arent covered under powertrain. That doesnt make too much sense to me as a warranty plan, I think everything that needs to be functional to run the engine should be "covered" if they call it a "powertrain" warranty. With this first visit, the code was for a Cam Sensor Actuator, and they called back and said that this part was indeed covered under warranty, so they replaced it. The truck drove great for about a month, then I started getting a really rough idle, hard starting, but this came and went occasionally, and while I was in Moab for the BSHS week, Speedy alerted me to a loose sensor wire problem that he has heard of before, we tugged at the wire on the cable housing for the intake side Cam Sensor, and the engine started running fine again. Last week I was down in Phoenix, and I got a really rough idle again, this time more pronounced than the first, I tried strain relieving the cable at different angles, nothing seemed to help, so i pulled the code, it was a Cam Sensor Bank A Malfunction code, the part was only $29.99 from AutoZone, so I replaced the cam sensor. WOW what a difference that made! I had been concerned for a while that my engine was either wearing out or losing cylinder pressure or timing or something because I wasnt getting the same amount of power out of it that I used to. On a side note and a bit of a separate issue, over the last 20k miles i've noticed decreased acceleration potential, nothing bad like when the CEL is on, but the truck has definitely lost some pep in its step. Replacing the cam sensor seemed to clear things RIGHT UP. Not only was the engine idling normally again and running well, but it seemed to have the same amount of power as the day I drove it home from the Dealership. I was able to hold 75mph on cruise control from Phoenix all the way to Flagstaff, and have never been able to do that especially on some of the hills. Very happy with the results, and this makes sense, as with a VVT engine and any engine at that, timing is critical to produce max power/fuel economy.

Well as of last night, the problem is back. Rough idle, and decreased accelleration even when it clears up occassionally, no CEL, and I imagine it will take a few days before I get a CEL like the last few times. I'm officially out of ideas, and after talking with some of the mechanics, I am not really sure anymore that there are any Aces in the shop at the GM dealer up here....



http://www.hummerforums.com/forum/hummer-h3-17/cam-sensor-12751/

 

[M22KLARS]

How is your TB looking?

 

[H32NV]

ive never looked at it actually, but i assumed since the problem comes and goes that whatever is causing it must be a temporary symptom. In my experience, when timing belts jump timing, they JUMP timing, and never fix themselves - but that has been on japanese engines.... When is the service interval for a timing belt on the 5-cyl?

 

[3rdH3]

No timing belt. It has a chain. As others have mentioned, I would clean the throttle body. If you are in the 80K range and it has never been cleaned, it likley needs it even if it is not causing your current condition.

 

[H32NV]

I can clean it tonight. any advice on things to pay special attention to?

 

[alrock]

I can clean it tonight. any advice on things to pay special attention to?

Don't shove a lot of dirt into the intake

Take off intake and resonator. I think the socket is 10mm but that's purely from memory. This is what I removed

There's a hose on the bottom. You'll need to disconnect it to remove the resonator and reconnect it when finished.

Pick up Throttle Body cleaner. Wipe as much off as you can and then follow the instructions on the can. Then you can go from this:

To this: