i just bought this car and it has about 6+ random codes ill list if needed but I've replaced alt and batt. I'm convinced its not the sensors at faulty any ideas I'm thinking grounding problem, maf, vacuum, maybe just the knock sensor?

 

thnks

What are the 6 codes?

iac, maf, knock sensor, cam angle sensor, tps, 02, atmospheric pressure. some have come gone and came back.

 

also air flow sensor

Edited May 6, 201213 yr by Rayg91

This mornings codes are 49(air flow sensor) 45(Atmospheric pressure sensor) 13 (cam angle sensor) 22(Knock sensor) 24(air control valve) 31(Throttle sensor)

What method are you using to pull the codes? There's test, current codes and code history mode depending on how you hook the diagnostic connectors together.

 

There should be a couple grounds attached to the intake manifold from the engine harness. Make sure they're clean and tight. There's another one between the top of the transmission and the firewall but it's less crucial. Then there's another between the battery negative terminal and the fender.

Check the harness plugs on top of the bellhousing. Pull them apart, spray some electronics cleaner in them, plug and unplug a few times and spray again then let them dry before plugging back in and starting the car.

I've seen this behavior from other 90/91's.... the code soup. One of my customers had this happen after we had some sensors disconnected for some troubleshooting. Try as we might we could not clear the codes nor extinguish the CEL. The car ran completely fine otherwise. A week or two later the CEL just went out on it's own and hasn't come back.

 

Primitive OBD-I self-diagnostic mode. I'm sure with a SSM you could make it behave. But I've only had luck with checking everything over carefully and then waiting for the ECU to cycle through enough drive cycles to correct itself.

 

GD

im plugging the two black connectors together to get codes. I've replaced the main ground from the batt to block and to fender. ill check the ones on the manifold and ill clean those plugs also and see how it goes