One thing after another on this car I swear

P0102 is a Mass Airflow Sensor code but I switched one out from Pick-n-pull and still the same issue. I took out an OBD-II and shows that it gets to about 0.007 lb/min and when driving gets to about 0.013 lb/min. I looked at the graph and it looks as if it goes up and down.

Symptoms include Limp mode, wavy idle on warm up, loud popping exhaust on decel, limited to only 2.2k Rpm, a check engine light of code P0102, a warm idle that drops occasionally, hesitation on a quick step of the gas.

After a long while, the car begins to act normal again, and I’m not even sure how that works. I do say that it did rain a bit too much here in the bay area lately if thats of any importance. I did check the fuse box next to the battery but not sure how to even diagnose that, I don’t see any water on or around it. I tried messing with the MAF, did the little reset and everything while in limp mode didnt fix it. Cleaned it then tried again, cleaned the other one then tried it again, same reading and same everything, even unplugging the MAF completely doesn’t change a thing. I looked at the plug, looks fine to me, even sprayed some MAF cleaner in there as well and the MAF port just to be safe. Im not even sure where to start if its a wire problem…

but the two times this happened, it goes away, after about an hour or an hour and a half and begins to read in the normal range of 0.4 lb/min for the MAF.

Any one else that would like to chip in would be a great help, thank you

 

Im going to disconnect the battery and press on the brakes and the horn a few times just to be safe, hopefully this will work.

 

Did not work. Still trying stuff, maybe the throttle body relearn thing

 

Actually P0102 doesn't necessarily mean it's a BAD MAF sensor, it just means it's low voltage from the MAF signal back to the ECM, if you have a big vacuum leak it can cause this code too.

The MAF sensor is a sealed harness but you can still get into it with backprobe pins.

Pink wire is from the fuse, should be 12vdc

Black/white stripe wire is ground

Orange wire is signal voltage back to the ECM, at idle it will be like 1vdc, and it will increase linearly as you increase rpm up to almost 4vdc at redline. So 3500 rpm will be about the halfway point so 2.5 vdc or so.

If that voltage is returning excessively low it means there's not enough AIRFLOW across the MAF, if you have a big vacuum leak downstream between the MAF and the engine then it will be sucking that unmetered air and not enough air flows across the MAF, thus the MAF heater doesn't need to use as much power to maintain temperature, thus it's using less voltage, thus the ECM sees "low voltage".

EDIT: Hesitation when stomping the throttle is also a primary symptom of a vacuum leak, primary culprits are either a torn/loose intake tube, or a stuck PCV valve. Or a ripped/loose PCV hose, there are 3 hoses for the PCV system on these engines, intake tube to left valve cover, the crossover tube at the front of the valve covers, and the PCV calve in the right side valve cover up to the intake plenum.

There's also the big brake booster vacuum line that runs from the right side of the intake plenum, into the battery box, then transitions to a metal tube as it crosses behind the engine through the wiper motor and linkage cowl, then it transitions to rubber again when it gets into the brake box where the booster is.

 

Hey Cleric, ahh so I could be sucking air from somewhere past the MAF which is why my car still runs fine but the MAF thinks otherwise? Its so confusing because after a while, the thing runs fine once I turn it off and turn it back on. Once I’m off work I will check around the intake, didn’t really pay no mind it could’ve been that as well. And for the electronic stuff, Ill check that out as well and see whats going on.

I did also notice that vacuum line behind the battery as well and ill decide to check that out as well. Though bad news, someone hit my car recently and chances are its totaled just from a fender bender. I might not be a G owner any longer if the inspection/estimate people says so… Dreadful

Thanks for the Help as always Cleric

 

The car when after a while goes out of said limp mode, works totally normal, car drives fine, no hesitation, revs through out the whole range and no 2.2k limiter, I might have forgot to mention that

 

Probably it's "fixed" once it gets hot and things expand and seal up, but then persist again once the engine is cold?

If that's the case then I'd start by checking vacuum lines, typically a rip in an intake tube won't mysteriously "fix itself" like a leaking PCV hose will.