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Mass Air Flow Issues..

M

Marley

New member
Hi there.. I have got a 99 Grand Prix GTP 3.8L supercharged.. Car ran fine no Check Engine lite no problems and completely able to bury the boost gauge in the dash at any given time.. Then the transmission messed up.. So I pulled the motor and trans.. split them and got the trans rebuilt and put it all back together.. And it ran and shifted great! Happy Fat Kid!! Then one morning shortly there after it started to idle funny.. still no check engine lite.. but it has about 170K miles so I dumped in some stp fuel injector cleaner and sprayed in some throttle body cleaner.. and yes I used actual throttle body cleaner not the carb cleaner because I have seen that anger them in the past.. Anyway.. this is where it gets crazy.. now I have a check engine lite that first said MAF low circuit input voltage.. and now to add to it I have a P1676 Code which is for the purge cylinder.. which is brand new.. also the MAF is brand new.. unplugged the MAF with the key on and measured voltage and its dead.. I know for sure its not the sensors and I cant seem to find any bad wires.. Also now the thing will only build boost up about half way on the gauge in the car.. Am I missing something obvious?? I am running out of ideas here and any help would be much appreciated!!
 


check the wires to the maf, and also check the fuse box for a blown fuse. maf has a fuse. im not sure what its listed as so maybe check them all.

same with the evap purge, check the wires, make sure its plugged in.
 
Agree with the fuse box. I had the same issue with idling and stalling from a blown fuse and MAF was not reading anything. Its under the hood, middle right. My O2 sensor wire was touching my headers causing it to short out the fuse. That fuse goes to quite a few things in the car so look out for that if that fuse is blown and keeps blowing.
 
For the down stream O2 sensor I have an emulator in its place and during the motor install that harness got pinched now that I think about it.. I will check there tonight and check the fuse.. If that fuse controls a bunch of different stuff including O2 sensors that could very possibly be where the problem lays.. Thanks for the outside opinion guys.. I was tearing my hair out.. I'll let ya know what I find for sure..
 


Well I found instead of where that harness got pinched I also had the wires for the upstream O2 sensor touching the headers which was the issue.. however GM in there wonderful wisdom put 2 pairs of black and white wires in the harness for that 02 sensor.. so when I repaired them I had no clue which was which.. so I took a crack at it and when I turned the key on to start the car the plug for the upstream O2 sensor literally burst into flames and almost burnt the car.. So.. its running now.. no more MAF issues.. and I have all my boost back.. however does anyone have any clue how to tell which wire is which in that harness?? As it stands right now I'm going to leave it be until I have a for sure answer on what does what.. I have been a firefighter for 13 years.. but I'll be totally honest that scared me a little.. haha!!
 
i could see this happen if the wires were burnt right through, and you had to guess. sucks i would have freaked out a bit too.

if they were still connected you could have cut and fixed one by one, that way theres no guessing where the wires go. or tape each wire, both sides, and mark them, then cut and extend them.
 
Yeah I had 2 pieces that were a melted mess on both ends.. no way of tracing them.. So does anyone out there have a way to tell what is what in that harness??
 
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