MAF burnoff circuit problem
01-23-2002, 02:01 AM
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Car: '88
Engine: 305tpi
Transmission: t-5
MAF burnoff circuit problem
Hi. My '88 trans am GTA with a 305tpi and 5speed is acting up. Its running really really rich, and kills when I pull it out of gear usually, unless I "save it" by tapping the gas on the RPM's way down. The car runs better in the cold though. stil not great, but it doesn't try to kill as often. The CCCS told me #36 which is a few possibilities, but the one I suspect now is MAF burnoff circuit problem. Someone had told me to try the Ignition Module, but I did, and that isn't the problem. How do I check the MAF Burnoff circuit?? please help!!!!!!!
01-25-2002, 05:54 AM
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try hooking a digital voltmeter to teminal D on your MAF sensor then start the car and run up to 2000 rpm drop to idle and turn off then watch voltmeter you should see a 12 volt reading.
The burnoff function is controlled by the ECM somehow and kicks in after the car has been driven X amount of miles or exceeds x mph I think it starts 10 seconds or so after shutdown and goes for 20 or 30 seconds. I tested mine the above way and it worked 3 out of 4 times maybe I didnt convince the ECM the other time, sometimes you can actually hear the relay kick in.
I kept getting code 36 even though I had power at terminal D and the relay worked when I put power to it but for some reason the code kept coming until I replaced the relay probably had the ****s and wasnt talking to the ECM
The burnoff function is controlled by the ECM somehow and kicks in after the car has been driven X amount of miles or exceeds x mph I think it starts 10 seconds or so after shutdown and goes for 20 or 30 seconds. I tested mine the above way and it worked 3 out of 4 times maybe I didnt convince the ECM the other time, sometimes you can actually hear the relay kick in.
I kept getting code 36 even though I had power at terminal D and the relay worked when I put power to it but for some reason the code kept coming until I replaced the relay probably had the ****s and wasnt talking to the ECM
01-26-2002, 01:47 PM
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Re: MAF burnoff circuit problem
Originally posted by gtaeric
Hi. My '88 trans am GTA with a 305tpi and 5speed is acting up. Its running really really rich, and kills when I pull it out of gear usually, unless I "save it" by tapping the gas on the RPM's way down. The car runs better in the cold though. stil not great, but it doesn't try to kill as often. The CCCS told me #36 which is a few possibilities, but the one I suspect now is MAF burnoff circuit problem. Someone had told me to try the Ignition Module, but I did, and that isn't the problem. How do I check the MAF Burnoff circuit?? please help!!!!!!!
Hi. My '88 trans am GTA with a 305tpi and 5speed is acting up. Its running really really rich, and kills when I pull it out of gear usually, unless I "save it" by tapping the gas on the RPM's way down. The car runs better in the cold though. stil not great, but it doesn't try to kill as often. The CCCS told me #36 which is a few possibilities, but the one I suspect now is MAF burnoff circuit problem. Someone had told me to try the Ignition Module, but I did, and that isn't the problem. How do I check the MAF Burnoff circuit?? please help!!!!!!!
01-26-2002, 11:28 PM
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Car: '88
Engine: 305tpi
Transmission: t-5
Where would I get a scanner? Are they expensive? And, is the Burnoff circuit in that harness that plugs into the bottom of the MAF? Electronics intimidate me! Thanks for the help so far everyone.
Thanks for the help so far everyone.
01-27-2002, 09:37 PM
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Originally posted by gtaeric
Where would I get a scanner? Are they expensive? And, is the Burnoff circuit in that harness that plugs into the bottom of the MAF? Electronics intimidate me! Thanks for the help so far everyone.
Where would I get a scanner? Are they expensive? And, is the Burnoff circuit in that harness that plugs into the bottom of the MAF? Electronics intimidate me!
Thanks for the help so far everyone. I wonder if you can see the coil get hot if you looked in it? If it got hot enough to burn off, I would think it would glow red hot. I'll hook it back up and watch how long the burn off last. I just know I wonder if mine worked so I hooked up the scan tool and watched it.
Good luck...
01-28-2002, 01:49 AM
#7
Eric,
Try the simple things first. Usually that's the cause anyway. Don't make it more complicated than it has to be.
You already have all the tools you'll probably need. The jumper you used to retrieve the error codes should be sufficient.
Make sure the electrical connector at the MAF is securely plugged in and clean. Exchange the MAF power and MAF burnoff control relays, then clear the DTCs by disconnecting the battery for a few minutes. Operate the engine for a few run/off cycles, then scan for error codes again.
If the code changes from a '36' to a '34', one of the relays has failed. I'd replace both just for grins, since they're only about ten bucks each. The engine would be running poorly if the MAF hot wire were not burned off and was collecting debris. The debris acts as an insulator and causes the MAF to read a lower incoming air flow than it should (since it rejects less heat to the surrounding air).
If the error code remains the same, make sure the burnoff is not being interrupted by the auxilliary iol pressure switch opening and closing after the engien is shut down. Make sure the connections are tight at the switch and that the switch is opening after the oil pressure has dropped on shut-down. There have been instances where the burnoff was interrupted by a failing pressure switch and the cycle would never complete, setting the code and allowing buildup on the hot wire over time. That's a remote possibility, and 95% of the time a relay cures the problem.
Try the simple things first. Usually that's the cause anyway. Don't make it more complicated than it has to be.
You already have all the tools you'll probably need. The jumper you used to retrieve the error codes should be sufficient.
Make sure the electrical connector at the MAF is securely plugged in and clean. Exchange the MAF power and MAF burnoff control relays, then clear the DTCs by disconnecting the battery for a few minutes. Operate the engine for a few run/off cycles, then scan for error codes again.
If the code changes from a '36' to a '34', one of the relays has failed. I'd replace both just for grins, since they're only about ten bucks each. The engine would be running poorly if the MAF hot wire were not burned off and was collecting debris. The debris acts as an insulator and causes the MAF to read a lower incoming air flow than it should (since it rejects less heat to the surrounding air).
If the error code remains the same, make sure the burnoff is not being interrupted by the auxilliary iol pressure switch opening and closing after the engien is shut down. Make sure the connections are tight at the switch and that the switch is opening after the oil pressure has dropped on shut-down. There have been instances where the burnoff was interrupted by a failing pressure switch and the cycle would never complete, setting the code and allowing buildup on the hot wire over time. That's a remote possibility, and 95% of the time a relay cures the problem.
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01-28-2002, 02:34 AM
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mesuring air
hi Vader
You`re great help but I wonder if it`s not the opposute about air mesure?
when wire is "dirty" and collected some debris, maf reads MORE air flow than it really is , thats because car`s that rich. If it would sens less air there would be less fuel than needed. but the car is too rich and I bet it has black smoke comming out. I had some problem with maf someday.
damm I bought a new maf, maybe I didnt had to, maybe I should just change those relays. lucky it was used=cheaper then new.
U know how hard it was to find one in Poland?
but ist from 305. I`ve seen in some catalog a replacmet for maf
, wihout that thin hot wire, there was some metal plate, much stronger that wire.
does anyone how where to buy it and how much it costs?
You`re great help but I wonder if it`s not the opposute about air mesure?
when wire is "dirty" and collected some debris, maf reads MORE air flow than it really is , thats because car`s that rich. If it would sens less air there would be less fuel than needed. but the car is too rich and I bet it has black smoke comming out. I had some problem with maf someday.
damm I bought a new maf, maybe I didnt had to, maybe I should just change those relays. lucky it was used=cheaper then new.
U know how hard it was to find one in Poland?
but ist from 305. I`ve seen in some catalog a replacmet for maf
, wihout that thin hot wire, there was some metal plate, much stronger that wire.
does anyone how where to buy it and how much it costs?
02-02-2002, 03:02 AM
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Car: '88
Engine: 305tpi
Transmission: t-5
I replaced the MAF burnoff relay, and nothing changed!!
I am about to give up and take it in. Very frustrating! And to top it all off, I can't get the CCCS to work anymore!! But, thanks for your help anyway. If anyone has any more ideas, please post. I forgot to mention before that the car is running REALLY rich...8 mpg. Later.
I am about to give up and take it in. Very frustrating! And to top it all off, I can't get the CCCS to work anymore!! But, thanks for your help anyway. If anyone has any more ideas, please post. I forgot to mention before that the car is running REALLY rich...8 mpg. Later.
02-08-2002, 03:17 PM
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Car: '88
Engine: 305tpi
Transmission: t-5
I got some free time today and I went out to mess with the car again. I found that the car ran the same way with the harness underneath the MAF sensor disconnected as when it is connected. And so I switched that MAF with the one out of my other '88 GTA, and nothing changed. What does this tell me? Could that harness be bad?
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