Peer81
Well-known member
Hello everybody,
My friends '86 convertible gives a code 34.
Strange thing is, while cold it starts rev's up to around 1000 rpm then starts running rough drops rpm and dies. This all within 1 minute. But if you keep up the rpm with your feet the engine will warm up. Then the engine will run just fine. With the next cold start same problem...
So we looked into the code 34. When unplugging the MAF and cleared the codes the new code is a code 33. So the ECM should be fine and the MAF could be bad. The GM manual shows a diagram with the MAF wiring. While checking the dark green wire from the ECM it gives 5 volts while running, so that is oke. The purple wire from the power relay also gives the 14 volts like it should.
Now the question, how do I know or how can I check if the burn off relay is causing the problem or the MAF is really bad. A scanning tool is on the way so we can check if the MAF readings are in check. But can I also check the MAF for a broken wire by simply checking for resistance on the wire terminals?
In another topic I found there is a little mistake in the GM manual as the power and burnoff relays are switched, is this true? I know they're behind the battery against the firewall.
Ofcourse it's always better to first change the (cheaper) relays and after that the MAF if the problem is still there, or is everthing so dependent on each other that with a broken MAF the relays can also be damaged?
Last, if the MAF is defect. He is looking into new or modified ones, some pro's or con's? There are modified MAF's without the screens and cooling fin's are they worth the extra money or will removing the screen on a new one give the same effect? (as he already has a 52mm BBK throttle body and a KN airfilter?)
Greetings Peter
My friends '86 convertible gives a code 34.
Strange thing is, while cold it starts rev's up to around 1000 rpm then starts running rough drops rpm and dies. This all within 1 minute. But if you keep up the rpm with your feet the engine will warm up. Then the engine will run just fine. With the next cold start same problem...
So we looked into the code 34. When unplugging the MAF and cleared the codes the new code is a code 33. So the ECM should be fine and the MAF could be bad. The GM manual shows a diagram with the MAF wiring. While checking the dark green wire from the ECM it gives 5 volts while running, so that is oke. The purple wire from the power relay also gives the 14 volts like it should.
Now the question, how do I know or how can I check if the burn off relay is causing the problem or the MAF is really bad. A scanning tool is on the way so we can check if the MAF readings are in check. But can I also check the MAF for a broken wire by simply checking for resistance on the wire terminals?
In another topic I found there is a little mistake in the GM manual as the power and burnoff relays are switched, is this true? I know they're behind the battery against the firewall.
Ofcourse it's always better to first change the (cheaper) relays and after that the MAF if the problem is still there, or is everthing so dependent on each other that with a broken MAF the relays can also be damaged?
Last, if the MAF is defect. He is looking into new or modified ones, some pro's or con's? There are modified MAF's without the screens and cooling fin's are they worth the extra money or will removing the screen on a new one give the same effect? (as he already has a 52mm BBK throttle body and a KN airfilter?)
Greetings Peter