I've been having a very annoying problem lately with my '91 N/A coupe. Under hard acceleration, The engine light randomly flickers above, say, 4000 rpms. Every time it flickers, the engine momentarily stumbles.
So, I decided to check for engine codes. The first time around, It showed code 13 (Pressure sensor). So, I did a visual inspection and found nothing wrong.(I haven't tested the sensor yet). I merely disconnected the battery to reset the code because I've had random codes in the past, but the parts were fine.
The next day it started getting worse. After a hard run, the engine light eventually stayed on and the car went into limp mode. Now I was seeing codes 13 and 27 (Oil Metering Pump). I reset the codes and the car was fine.
Now, what confuses me is the fact that the OMP specs out just fine as per the FSM. I also have the entire OMP disconnected from the block because I'm running premix. The OMP stays connected and sits next to the charcoal canister. I have no idea why I'm getting these codes, and yes, I have run an entirely new grounding system in my car. I'm also going to check the values of the pressure sensor tonight.
(P.S: It seems that everytime the pressure sensor sees positive pressure (the very little pressure that the engine develops once the actuator opens for the whole "dynamic pressure" to take effect), it throws out a code or 2. As for the OMP?? I have NO idea. I've been having intermittent problems with it.)

Brian

 

You ever heard of an intermittent problem?
The E-OMP would do that.
I've seen E-OMP's intermittently fault, and it causes a flickering CHECK ENGINE light as you have experience.

YOU CAN'T VISUALLY STARE AT THE PRESSURE SENSOR AND VERIFY IT'S OKAY.
It's a pressure transducer sensor, so it's all solid state.


-Ted

 

Thank you for your input

 

Sounds like shitty grounding to me, it would explain everything.

The Pressure sensor is known to have a shitty ground. Check out the archives and do the supergrounding thread, I bet it would clear up your problems.

 

I was always led to believe that the bad grounding was only a problem with series 4 (86-88) FC's???

 

BTW, I have run an entire grounding system that goes from the ECU-->firewall on original grounding strap-->engine block on 2 spots-->alternator body-->back to chassis near battery-->then to negative battery post

 

Follow up:
I swapped my OMP with my friend's (he doesn't use it anymore), and it fixed the OMP code.
As for the pressure sensor, I installed an inline restrictor in the hose and it fixed the pressure sensor code. Seems to drive better......