brandywine
Well-known member
Hi all,
I have a 1980 with mildly modded ZZ4 and TPI. The PCM/ECU is from a 1990 and is a MAP system, not MAF.
I am getting an intermittant error code 33 - MAP voltage high - low vacumn. The engine runs normally, and then starts to run rough -hesitate/stumble. Within a few minutes the problem seems to clear up, but system is running in open loop. This has happened twice in the last 3 weeks. I have a scanner tool that I can use to read the codes, see the voltage, erase codes, etc.
I erased the code the first time and waited to see if it would come back. It took about 3 weeks. The problem seems to occur when the car is at operating temperature with a load.
The MAP sensor at idle is at 1.61V. With the engine off and the ignition on the MAP sensor reads 4.78V.
I have taken the MAP sensor off and inspected the plastic module and the hose that runs to the plenum for cracks or leaks. None found.
Does anyone have any diagnostics on this particular year/code (1990) that they can post. I'm not a TPI expert, so use small words...
Thanks in advance.
I have a 1980 with mildly modded ZZ4 and TPI. The PCM/ECU is from a 1990 and is a MAP system, not MAF.
I am getting an intermittant error code 33 - MAP voltage high - low vacumn. The engine runs normally, and then starts to run rough -hesitate/stumble. Within a few minutes the problem seems to clear up, but system is running in open loop. This has happened twice in the last 3 weeks. I have a scanner tool that I can use to read the codes, see the voltage, erase codes, etc.
I erased the code the first time and waited to see if it would come back. It took about 3 weeks. The problem seems to occur when the car is at operating temperature with a load.
The MAP sensor at idle is at 1.61V. With the engine off and the ignition on the MAP sensor reads 4.78V.
I have taken the MAP sensor off and inspected the plastic module and the hose that runs to the plenum for cracks or leaks. None found.
Does anyone have any diagnostics on this particular year/code (1990) that they can post. I'm not a TPI expert, so use small words...
Thanks in advance.