AcidShock

iTrader: (49)

Okay, so I have heard that when the electronic MOP goes out it can sometimes takes the ECU with it. Rather, the control circuit for the MOP on the ECU board. I cannot find how to identify what circuit is bad, can someone point me in the right direction.

Background: MOP died in my S5 GXL, threw code 27. Replaced MOP, started to drive it around, and it fell on its face. Tried to pull codes and the CES light goes out, comes on and stays on. Does not blink. Tested MOP for proper ohms at the terminals and it checks out fine.

brohr01

USE SEARCH

AcidShock

iTrader: (49)

Haha, eat poop.

brohr01

seriously though, i think this might help from what i have read.

RotaryResurrection

iTrader: (8)

Generally what happens is you get the OMP code, replace the OMP with a known working one, and still get the OMP code. IT's because the ecu's omp control section is dead and it won't recognize/control the new omp anyway, so you still get the code.

AcidShock

iTrader: (49)

Well, I thought that might have been the case. Right now I can pull no codes because the CES light just comes goes off then comes on and stays on. No blinking.

AcidShock

iTrader: (49)

I have the ECU out of the car and apart and am looking over both boards. I cannot see any burnt area, broken resistors, or combination of the two. Is there a specific one that gets burnt that I can test?

AcidShock

iTrader: (49)

Started screwing around again and when I check the the voltage at terminal 2A on the ECU, I cannot get 1 volt. This is all per FSM. Also, I am not getting continunity at terminals SM1 => 3S, SM2 => 3T, and so on. I am getting 12 volts though. Does this mean the engine harness is hosed?

AcidShock

iTrader: (49)

Up for any suggestions/help.

AcidShock

iTrader: (49)

Forum glitch.

AcidShock

iTrader: (49)

I just thought of this just now... there is a bare wire on the AFM harness where it plugs into the AFM. All the wires are secure and accounted for, but there is this silver, bare wire poking out along with the other crimped ones. What is that for and could it be causing this problem?

I have checked the IAT and it reads 41.7 KOhms at ambient temperature (64 F). Is this normal or abnormal? What else should I be checking?

scathcart

The CEL is supposed to stay on.
Ground the single green ISC by the leading coil, then turn the key to run (but don't start the car). Now you should get the flashes.

Also, did you make sure to reset the ECU after installing the new MOP? Pull the negative batt cable and step on the brake pedal for 5 seconds?

AcidShock

iTrader: (49)

Sir, I have grounded the single green connector and that is what happens when I ground it. It goes off, comes on and stays on. I have reset the ECU multiple times as well.

ultradef

Sounds like the same exact problem I'm having. My OMP was shot (throwing code 27), so I replaced it. I'm not 100% sure that the replacement OMP works, but I hope that the person I bought it from would not sell me a broken one. Started her up, drove her down the street and the CEL and limp mode came on again. Tried to check the codes, but there was no blinking. This is the kind of **** that makes we want a standalone...

I still have to check the ECU, wiring harness, and the replacement OMP, I'll let you know if I figure it out.

AcidShock

iTrader: (49)

I know my MOP works because it came from a known working car. It also tests within specification per FSM. I tested the TPS yesterday and that too tests within limits per the FSM. I tested it with it on the car so as to avoid reading it wrong.

The thing that is getting me is that I cannot get continunity between the MOP end of the harness and the ECU end of the harness. I have tested and restested for continuity just to make sure it is not human error and it is just not there. It really makes me wonder if that length of the wiring harness is fried somehow due to the MOP going out.

Also, are there any other sensors on the car that would cause limp mode besides the AFM and MOP? Something else that is strange is that the car will buck like crazy and backfire if I try to give it gas below 3K RPMs. If I very slowly accelerate (no bucking) to above 3K RPMs, I can get the car to go reasonably well. It does not seem to hesitate as bad or buck hardly at all. This is getting weird...

pistonhammer

I am having the exact problem discussed in this thread. Did you find the problem?

NightsEmbrace

I am AcidShock's fiancee and the car in question was my car. It has been awhile ago, but I believe the problem was the ECU, it was remanufactured or something like that and it was not working correctly anymore. We put another one in and the car worked perfectly.