DRGrocho Posted November 8, 2008 Report Share Posted November 8, 2008 So, my 1999 3.8 liter Lumina has developed some idle problems. It will do the idle relearn procedure fine, and idle well sometimes, but other times it is hard to start and won't idle at all. The only trouble code I'm seeing is a P0102, low MAF circuit voltage. I had been getting this code for a while intermittantly with none of these symptoms, but about a week ago I got a new one and swapped it in. About 1000 miles later, I developed these idle problems. Today I put in a new IAC, and within the last year it's gotten a new fuel filter, new upper intake, all new ignition system, alternator, and fuel pressure regulator. It seems like the problem is exacerbated when the temperature is up, however, it does die sporadically at low temperature, and it will idle from time to time at high temperature. I don't think it is a vaccuum issue because I have done some checking, but obviously I can't rule it out either. Also, unplugging the MAF doesn't make a difference. I've checked the TPS, and it ranges from about 4.57 in closed position to about 0.87 in open, which as far as I can tell is acceptable. At this point I'm thinking maybe to try a new MAF or maybe an EGR issue. If somebody has had a similar issue and can link me to their thread, I'd appreciate it as for some reason I am having trouble using the search function on the forums. Otherwise, any suggestions would be appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
Andrew Posted November 8, 2008 Report Share Posted November 8, 2008 the temp weirdness leads me to think its the coolant temp sensor. could be bad or just gunked up from the Dex. Quote Link to comment Share on other sites More sharing options...
DRGrocho Posted November 9, 2008 Author Report Share Posted November 9, 2008 Also, above 1000 rpm, the car is fine. When it idles, its around 7 or 800. When it is trying to die, I can sometimes save it by punching the accelerator for a bit until it becomes stable again. I can get it to idle more often by easing it down into the idle range than by just letting the rpms fall naturally. Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted November 16, 2008 Report Share Posted November 16, 2008 I had same code/ problem 1 year ago on my 98 Z34. Replaced MAF with known good one from JY, cleaned before install. Car worked great. BUT, I previously eliminated my wiring also, by checking for a 5V VREF (Voltage Referance) and good ground. If the VREF wire is shorting, it will make all other sensors go wacky since it's tied to most of them, all sharing the same 5V VREF (CTS, MAP, TPS and so on.) So definitely check wiring if you haven't done so already Quote Link to comment Share on other sites More sharing options...
jimmyfloyd Posted November 18, 2008 Report Share Posted November 18, 2008 yeah, sounds like a bad MAF to me. Unplug the MAF sensor when the car is running and see if it gets better. If so, replace the MAF. You could remove the MAF and clean it, but you have to be careful when doing that. I'd find a spare and replace it personally. Quote Link to comment Share on other sites More sharing options...
Andrew Posted November 19, 2008 Report Share Posted November 19, 2008 you can clean the MAF with MAF cleaner only. you dont happen to have a K&N air filter do you? Quote Link to comment Share on other sites More sharing options...
oldscsc Posted November 19, 2008 Report Share Posted November 19, 2008 you can clean the MAF with MAF cleaner only. you dont happen to have a K&N air filter do you? Eye due. Y duz this matur? Quote Link to comment Share on other sites More sharing options...
Andrew Posted November 19, 2008 Report Share Posted November 19, 2008 if you over oil a K&N, the oil can actually coat the MAF and cause weird readings. Quote Link to comment Share on other sites More sharing options...
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