2005 G has MREV1 w/ 5/16" spacer and Stillen CAI since August 2005.

Car threw a check engine light. Took it to AutoZone to have the code read; codes 171 and 174, Bank 1 and 2 too lean. Had the 15,000 mi oil change coming up, but before I took it to the dealer, I tried completely tightening everything after the MAF, disconnecting power for 12 hrs to reset the ECU..... and after some spirited driving (after properly warming her up of course) it threw the code again.

Anyway, the dealership went to check out the problem, and they apparently found out by spraying carb cleaner that the gaskets around the spacer are leaking. Told me they could replace the gaskets for 300 bones....

So I said I will deal with since I am the one who installed the spacer/lower collector in the first place.

I loosen all of the bolts on the upper plenum in the correct order and retorque them down to spec. Start the car and spray some carb cleaner, and I cannot seem to get it to idle strange - peaks or valleys. So I think it is fixed. Reset ECU, 2 days later, throws the code.

I would think it might be a bad O2 sensor, but on banks 1 and 2 at the same time? Also, if I rub my thumb along the top gasket on the spacer in the front, I get some of the gasket to peel away - dry rot? rot? eh? That happened multiple times and I lost the very edge of the gasket.... not good I think.

Anyone have any ideas? Hydrazine got any advice? If I just need to replace the gaskets, I can do that, but it is kind of a PITA.

 

Yeah bad O2 sensors after 15k miles is strange, especially if you haven't touched them.

I'm not sure how well carb cleaner would work in a fuel injected car though...

Hopefully Tony can chime in and give you some insight!

 

did you spray the carb cleaner on the maf?

 

No, I didn't... could be worth a try to see if it is leaking, but the codes thrown show a discrepancy between the MAF value and the O2 sensor values, so there must be a leak between the two, and the dealer claims it is through the spacer.

Car doesn't really drive any different, even idles well, with a dip every once in a while, but that could be considered normal, and I know that the best way to find leaks is at idle.

Pretty confused here.

 

Did you put in new plenum gaskets?

 

1) Take off spacer, reset and see if it comes back. If no code..

2) Reinstall spacer with new gaskets and see if the codes come back

If codes come up after 1), take to dealer

 

Alright, take off the spacer and test it is. I guess it won't be THAT bad...

Thanks for everyone's help. This forum rocks.

 

MAF may have oil on it due to the Stillen CAI... try to clean it w/ MAF cleaner. Check out all intake manifold gaskets. And if your gaskets are rotting away,torn, or suspecious, change them out.

 

+1^

Check the MAF.

Unless something was installed incorrectly during the spacer install, its really hard to make the spacer gaskets leak. They are quite thick and compliant.

Spray some of that carb cleaner on your maf sensor and then gently blow it dry with compressed air. This should clean it well.

There is also one other thing you can try...

If the Throttle Body butterfly valve was somehow pushed on or disturbed during installation, it can change its calibration. A change in calibration can change the air flow rate at idle. This can also cause what you are seeing.

To do a throttle body calibration reset, download the installation manual from our website. The last page of the manual shows exactly how to do a TB recalibration.

Do a TB recal and MAF cleaning and the problem should go away.

If you have any questions feel free to give me a call.
(661) 993-5111

Tony