ive been having map probs for a while now and i just got around to checking on it.

today i replaced the map sensor and pigtail (soldered). and the problem remains. code 34 (wont idle)

i dont have any scan tools but i did a few tests today.

i checked the voltage from a to c and got 5v

i checked the resistance from b to the ecm and it was fine. i havent checked the ohmage from the 5v ref (a) or the ground (c). at the time i didnt think it was needed since they are used by other sensors and they seem to be working fine.

what else should i do to troubleshoot the problem besides just blow the car up?

 

DTC 34 = Manifold Absolute Pressure (MAP) sensor circuit (signal voltage low, high vacuum)

Turn the key on, don't start engine. MAP signal wire voltage (B to A) should be in the range of 4.5-5.0V, depending on what altitude you are at.

Then start the engine. MAP should be about 1.5V with a stockish cam. That corresponds to a 20"Hg vacuum. With a bigger cam, you might see readings in the 2.5-2.8V range.

The code sets when the MAP voltage drops to something like 0.25-0.5V at idle.

 

ill check those things as soon as possible. can you tell me what the possible causes of high vacuum could be, if the sensor, wiring and ecm check out?
i have a 230/236 544/554 cam

 

If you are seeing significantly more than 20-21"Hg, the most likely cause is a wiring or sensor problem. There's not much of anything mechanical that can cause the vacuum to be unusually high.

 

i checked a few things today.

key on B to A i got 4.8v

engine running (throttle proped a little open to keep it that way) i got around 2v.

i also checked the resistance on A and C back to the ECM and that checked out.

does that mean its time for a new ECM?

 

Sounds like the engine isn't getting enough air to idle. Have you checked the IAC passages to make sure they aren't plugged up? Are you sure the valves are adjusted properly? How big is the cam, and who tuned for it?

 

On my 93 I had the same problem and it turned out to be a bad map sensor then went to replace it and received a bum sensor.

That cam is not that large at all to cause you any problems. How does the car run besides the light. Does it idle correctly? Idle at all or just die?

Anything else that you have changed in the recent past as well. Also double check all your vac lines.

Another thing to look out for is that 93's take a few different parts than later years. I found that the hard way by using a 94 ICM and the car would run and drive but just be down on power and miss on the big end.

Just trying to stir your thoughts maybe.

 

i readjusted my valves today so i know they are right. the cam is only a 230/236 544/554 tuned by mad z28.

the problem did start after removing my intake to inspect my comp r's. while the intake was off i disassembled the throttle body to clean it. could i have messed something up?

 

update....

i took of the throttle body today and cleaned tha IAC and passages. i put the throttle body back on and now the car acts slightly different. when it starts up it imediately goes to 2500 rpm/ stays there for about 2 seconds and dies.im still getting the map code 34. could the IAC passages in the intake be clogged?

would datamaster tell me anything considering the car only runs about 2 seconds.

also my IAC pigtail is somewhat damaged, could this be the problem?