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2003 Monte-Hesitation, Stalling, P0102 Code
OK...I need some input from the good tech people on this forum.
Car has 139,000 miles. Recently the "Check Engine" light came on and started to get an erratic idle, going between 800rpm down to 600rpm. Then before I could diagnose it the car stalled on me a couple of times while coming to a stop. I then noticed that while driving if I accelerate up to about 40 miles an hour and let my foot of the gas that the tach would slowly decrease then jump down to 1000rpm and then back up to 1500rpm and so on. When I finally checked the codes it gave me a P0102 code, Low Voltage to MAF sensor. With my multimeter I checked the MAF sensor. There is 12 volts to terminal C to power with the key on, there is 12 volts to ground with the key off, terminal B. I checked the frequency of terminal A while running and it is a bit erratic between 100Hz and 130Hz. Thinking that since voltages were good that the MAF sensor was bad. I purchased a brand new Duralast MAF sensor. At the same time I put in a new air filter, the old one only had 15,000 miles. After I put in the new MAF sensor, the car ran worse. After starting about 10 seconds later it starts idling between about 1500 rpm and 500 rpm and developed loud sucking of air noise. Unplugged the new sensor and it smoothed back out and lost the noise. Thinking I could have received a bad sensor, I took it back and got another one. Installed it and the same thing happened. Since then I have tested the TPS with no issues. Cleaned the MAP sensor. Looked for other vacuum leaks and nothing. I have disconnected the battery multiple times and the Check Engine light always stays on. Not sure where to go next. I would prefer to diagnose instead of just replacing parts. Any good ideas for a next step would be greatly appreciated. |
Originally Posted by sjanson13
(Post 553182)
OK...I need some input from the good tech people on this forum.
Car has 139,000 miles. Recently the "Check Engine" light came on and started to get an erratic idle, going between 800rpm down to 600rpm. Then before I could diagnose it the car stalled on me a couple of times while coming to a stop. I then noticed that while driving if I accelerate up to about 40 miles an hour and let my foot of the gas that the tach would slowly decrease then jump down to 1000rpm and then back up to 1500rpm and so on. When I finally checked the codes it gave me a P0102 code, Low Voltage to MAF sensor. With my multimeter I checked the MAF sensor. There is 12 volts to terminal C to power with the key on, there is 12 volts to ground with the key off, terminal B. I checked the frequency of terminal A while running and it is a bit erratic between 100Hz and 130Hz. Thinking that since voltages were good that the MAF sensor was bad. I purchased a brand new Duralast MAF sensor. At the same time I put in a new air filter, the old one only had 15,000 miles. After I put in the new MAF sensor, the car ran worse. After starting about 10 seconds later it starts idling between about 1500 rpm and 500 rpm and developed loud sucking of air noise. Unplugged the new sensor and it smoothed back out and lost the noise. Thinking I could have received a bad sensor, I took it back and got another one. Installed it and the same thing happened. Since then I have tested the TPS with no issues. Cleaned the MAP sensor. Looked for other vacuum leaks and nothing. I have disconnected the battery multiple times and the Check Engine light always stays on. Not sure where to go next. I would prefer to diagnose instead of just replacing parts. Any good ideas for a next step would be greatly appreciated. Off brand Mafs (not an AC Delco)Tend to be a problem... Its recommended to replace the MAF with an AC Delco.:thumbsup: The way to check if you have a bad MAF...would be to unplug the MAF ,start the car and drive it....If the problem disappears then its definately the MAF!....It is "NOT" recommended to continue to drive around with the MAF unplugged!... This is for testing purposes only... I would also clean the IAC (idle air control) and the TPS to besure those are also problem free... Im guessing its the IAC....:thumbsup: Hope this helps... Im sure someone else will chime in with other idea/solutions as well! |
I agree with Dave when it comes to buying an AC Delco one. I had the same problem you had about a month ago and I went with the AC Delco brand when I bought a new one and it fixed it
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The chances of getting two bad sensors in a row seems pretty high. If the symptoms got worse I would suspect a problem with the wiring or connection. Run your tests again checking the entire length of the harness. Watch your meter for changes that might indicate an intermittent short/open in the circuit. If you haven't yet, clean the MAF connector. Since you were in the air box changing the filter I'd also go back to it, separate the halves and clean the two connectors plugged into the PCM. Before putting the PCM back in remove the rest of the air box and clean the ground wire on the top of the rail. CRC electronic cleaner works well for getting a good force of cleaner into the connectors. ;)
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Thanks for the suggestions. Still not fixed. Looks like I have a bigger issue and I just need to find out how to diagnose it.
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Did you get erratic readings on terminal A with the new sensor installed? There's not a lot to that circuit - MAF sensor, wiring and PCM. I suppose it's possible you did get two bad sensors in a row, but that would be rare. I also suggest using either an AC Delco or Delphi sensor. A lot of people have reported having problems with other aftermarket brands.
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