Muj1896 Posted November 13, 2014 Report Posted November 13, 2014 Grasping at straws on this one here, so any help is greatly appreciated. My '99 Lumina LTZ is driving me nuts. So, here it is: it has rolling idle (between 500 -800) it almost sounds like a diesel loping. This is not consistent however, sometimes it will idle smoothly at 1000 or so. But, when its doing it there is this loud sucking sound like it just cannot get enough air. I thought maybe there was an issue with the air box, so I disconnected it from the tube and no difference. The sound almost reminds me of a cammed motor. It also has P0102 code for MAF. However the MAF has been replaced. Also it has code for rear O2 sensor as the cat and silencer have been removed by previous owner. But, one point in time after this was done the car ran fine, so I don't know that it has anything to do with the current problem, or if maybe it is exacerbating the problem. From what I understand, code means that the MAF is sensing less air than the O2 sensor or something, which made me think the motor was getting air from some other source. So, I did a an air leak test with brake cleaner and got absolutely nothing. I sprayed the stuff everywhere, and didnt get a single rev. Oh, and also replaced UIM gasket thinking that might be the source. Going crazy trying to figure this one out, please someone, anyone, help me. Thanks ahead of time to anyone willing to help guide me on this one. Quote
Imp558 Posted November 13, 2014 Report Posted November 13, 2014 TPS? Perhaps the PCM is seeing a higher TPS reading than actual, and that may explain why it idles funny and why it expects the MAF reading to be higher. Stick a safety pin in under the seal in the back of the plug by the blue wire so you can read it and see if it's about .4V closed to 4.9V about open. Quote
Muj1896 Posted November 13, 2014 Author Report Posted November 13, 2014 Blue wire on TPS? Havnt done much testing with a multimeter. Could you please explain in greater detail? I have a small multimeter, not sure how to set it. Assuming I ground to common ground of the vehicle? Sorry for being newb, electrical testing seems to be the one thing that baffles me. Quote
Muj1896 Posted November 13, 2014 Author Report Posted November 13, 2014 I do however have a handy dandy scan tool that reads just about whatever if any information from the PCM might help? Quote
Luke94vert Posted November 13, 2014 Report Posted November 13, 2014 The maf and tps were changed out before you bought it. Quote
Muj1896 Posted November 13, 2014 Author Report Posted November 13, 2014 I knew the MAF was new because you told me you did that. You didn't tell me you did the TPS though. Quote
Imp558 Posted November 13, 2014 Report Posted November 13, 2014 Well, just because the TPS is new doesn't mean there still can't be an issue, could even be a splice in the 5V or Low reference to it. Check with the scantool and see if it reads correctly. Use that tool to check everything you can in fact. Can't get too much info... Quote
Muj1896 Posted November 14, 2014 Author Report Posted November 14, 2014 Okay, I'll run a scan tomorrow, and note down everything I can. Quote
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