Hello, I'm trying to determine if i fried my PCM, I have a check engine light but i only have access to a Innova scanner which obviously wont do anything for me. To start, the engine runs. Albeit pretty poopy it will crank and crank and crank for about 15 seconds before firing then it idles alright with a noticeable smell of fuel from the exhaust, and when i pull away from a light or stop it will miss like a gunshot but only once then pull away without any other issues besides some pretty bad vibration and lack of power.
THE FACTS:
new opti, ICM, coil, plugs, wires, TPS, MAP, MAF, Timing set, tested injectors for leaks, fuel pressure, ECT sensor. swapped opti, icm, and coil with other known good units with no change to symptoms. probably forgetting some stuff.
But while the car was running i decided to unplug the MAP and absolutely nothing happened, car continued to run as if i didnt do anything at all. Then i unplugged the MAF and it bogged for second then continued to run. Ive tested both pigtails for power and signal and they both seem good. Car started with oil pressure sensor unplugged(unsure if thats normal or not). To my knowledge the car shouldnt run at all without a MAP so im a little stumped here. Did i fry my PCM? it seems to act like its not receiving any incoming data and is just running the motor on a fixed A/F ratio and spark timing. Because it runs okay when cold but as the car warms shaking and rough running gets progressively worse, not when it goes into closed loop, just as the temp increases. I.E. running richer and richer as the temp goes up. Thoughts anyone?

 

You really need to get it scanned for codes. You might be able to fix the problem without throwing parts at it blindly.

 

I mean can you think of any reason the car would run with no MAP?

 

Why won't the Innova scanner work? Which model is it? There is a problem with the data base in one OBD-1 Innova, and it gives seven false codes. Is that the problem?

Downloading Scan9495 is free, just need a cable, and a PC or laptop. Much cheaper than pouring $$$$$$$$ into an unknown problem.

Oil pressure sensor has NOTHING to do with the PCM or the starter. Not like the 3rd Gens.

When you unhook a sensor, the PCM typically has a backup mode to keep the engine running. If virtually everything is missing the PCM has a “limp” mode that will run poorly, but get yo home. Very few people actually have their PCM go into limp mode.

 

its a innova 5300. It gave me 10 codes including 54 and 55 and gave me the same 10 after I cleared them by pulling the BATT fuse for 5 minutes. I don’t have a laptop or access to a tech 2. I can’t find a shop that either has a tech 2 or is willing to tell me if they do for some reason as there arnt that many near me and I don’t have a laptop. What can send the PCM into limp mode? Again I was under the impression that the motor wouldn’t run at all without the MAP.

 

Factory Service Manual info related to the MAP sensor:

Action Taken (PCM will default to): If the MAP sensor fails, the PCM will calculate a MAP value based on throttle
position and engine speed (RPM). The Malfunction Indicator Lamp (MIL) will illuminate.

You really need some scan data to help find the right path.

 

do you have a guide for testing the pigtail? Or tracing it back? Because I already tested my new MAP with a vacuum pump and it tested good, plugged in to the harness, key on, 5v atmo and it descended according to HgIn I applied.

 

This chart shows the wiring to the MAP, so you can check potentials. http://shbox.com/1/1995_pcm1.jpg
No/low vacuum=high voltage on the signal wire
High vacuum=low voltage on the signal wire
The best way to check the MAP and it's wiring is (drumroll...) scan data. Honestly, you just can't troubleshoot a modern car without this ability.

 

Tech 2 clone, reviewed by our resident expert in scanners:

https://www.camaroz28.com/forums/com...-price-879880/