hello--
i have a 1986 camaro z28 tpi

-SYMPTOMS-
idle is up and down between 750-1500rpm but mainly stays around 1000 in "P".
if you put the car in drive the idle drops way down and stumbles and sometimes it will just die and somtimes it can pick itself back up and it wont die in gear but is rough as hell. also if you turn the steering wheel, even in park, the car will do the same thing, it will just die and somtimes it can pick itself back up and it wont die.
When it idle real rought the whole engine shakes, its crazy.

-CODES-
34
36

Tested all relays and test all wiring to the maf. its a Wells SU-145
What would cause it to die when i turn the steering wheel or put it in gear?

Thanks

 

Blue86,

First, if you have the Wells MAF, there is no hot wire, so there is no need for a burn off cycle. However, your ECM doesn't know that, so the Wells MAf has to SIMULATE a burn off cycle on engine shut down. This still uses the MAF burn off relay on the firewall and a dummy load resistor in the MAF to "foll" the ECM into seeing a burn off load. If the MAF burn off relay is failing, you can generate a DTC 36. If the connections to or at the MAF are faulty, the same thing can occur. Since the burn off circuit is completed THROUGH the NC contacts of the MAF power relay, a faulty MAF power relay can caused both the DTC 36 AND the 34.



I'd advise checking the relays and wiring before condemning the MAF. If the MAF signal is not getting to the ECM, the engine will exhibit abnormal behavior. If you do find you have a faulty MAF, the Wells units have a lifetime warranty. Just be ready to PROVE the MAF is bad.

If you solve the MAF problem and still have the stalling and RPM "hunting", your next step would be to clean the throttle body, remove and clean the IAC, and set the TPS and minumum air position. That generally solves 99-44/100% of idle RPM issues.

 

I just went out to start my car and it started then died, then I went to crank it again and everyhthing went dead,somehow the negitive post wasn't connecting right on the battery and it reset the codes. So the idle went back to ok again(idled at about 900rpm in "P") and no codes! I have reset the codes a few times and have noticed a pattern. the code 33 and 36 will come on after I try to start it again after the codes were reset. To me the computer is trying to tell me the burn-off relay isn't working because it stored the codes in the ecm after the engine was shut-off leaving them for me the next time i try to start up. I unplugged the MAF with the engine running and tested each connection and here are the results(this is from memory):
Red Wire - 14.41V
Blue Wire - 5.0V
and the other two had like .1V or .01V can't remember

Seems like the MAF is getting the proper signal and it is brand new, and as vader mentioned it doesnt use the burn-off cycle, all the relays are new...is what is really eating at me and above Vader didnt attempt to answer, was why when i turn the steering wheel or when i put it in gear, the rpms drop and the engine tries to die, but will stay running if i tap the gas when it tries to die. can anyone answer this?

 

my guess would be the fuel pump is going south, you could get a fuel pressure gauge and test it. my car started the idle hunt when mine was going out and when I put it in gear it would idle down to near nothing or die. it would also throw codes at me for the maf and iac, etc hope this helps

 

You only determined if the MAF is getting the proper voltage. The signal is generated by the MAF and sent back to the ECM. If the ECM is not getting the signal, it won't act. Are the new relays the correct type? Do they have both NO and NC contacts?

You need to monitor the voltage on the red wire (terminal E) for two-six seconds AFTER the engine is shut off, not while it is running.



I did address the issue, but didn't elaborate on the reasons. Since you already have a MAF error code, the ECM is ignoring the MAF input and operating on base lookup tables for fuel and spark parameters. The ECM relies so heavily on the MAF for data that the base tables will only basically operate the engine. Until you get the MAF input working, the ECM barely operate the engine, and additional load from things like the power steering pump or a static torque converter turbine may not be offset by the IAC. With a working MAF, the system would react appropriately.

Basically, you NEED to solve the MAF issues first.