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What would cause a rotor not to fire?

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Old 07-15-02, 03:12 PM
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What would cause a rotor not to fire?

Okay before you all state the obvious....I have good compression. I do not believe any of my injectors are leaking because it holds fuel pressure after I turn the key off. I also have spark.

The car (1990 GTU) lost power while driving one day. I had just replaced the MOP with another used one. It went into limp home mode, then almost immediately lost all power. It would not idle on its own. I got it home, the only error code was for the MOP. But now it will barely start, runs weak and richer than hell. When I pull the plugs, the front rotor is firing, the rear is soaked in fuel.

The only things I have not tried to replace are the TPS and CAS. Is there anything else I should be checking?

Thanks for any suggestions,

Cardio
Old 07-15-02, 03:23 PM
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Ouch.... sounds like the MOP/OMP went out and starved the rear rotor of oil.
Old 07-15-02, 03:44 PM
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That was my first thought, but it has great compression on all three faces. The needle bounced straight 110-115's.

Cardio
Old 07-15-02, 03:50 PM
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Well, you could try an ATF treatment and some new plugs...that would get rid of the excess fuel. As for the cause, I don't think I've ever heard of that before...wish I could help.
Old 07-15-02, 03:55 PM
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if it has spark, fuel and compression it has to fire. you are missing one of those. lemme diagnose:
leading 1# fires, since they are waste spark, leading #2 fire also. plugs are soaked with gas; the fuel system works. the only other thing it could be is compression (unless you have an injector stuck open, or a huge vacuum leak)

mike
Old 07-15-02, 04:08 PM
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Could a vacuum leak cause this situation?

Cardio
Old 07-15-02, 06:28 PM
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I know this is a dumb question but have you cleared the error code?If I recall the code for the OMP stepping motor is 27 and it is a hard code(ie it will not clear itself).
A vacuum leak is very unlikely to cause the problem you describe.
Old 07-15-02, 06:47 PM
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I'm having the same problem right now as we speak. But mine happened sitting in the driveway right after I fixed my AFR. I'm thinking I knocked somthing loose in the ECU harness when rewiring my AFR.
Old 07-18-02, 10:28 PM
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Well,
My automotively inclined Uncle came in town this week. He was only here for a day before he brought my 7 back to life. Apparently my Metering Oil Pump Wiring Harness was bad. I happened to have a spare laying around (not perfect, but still a substitute), and after placing the new harness on, the car fired right up. NO SMOKE, NO FUEL COMING OUT THE EXHUAST. However it was severley out of tune from my frantic adjustments. An hour later, it was idling perfectly.

So, the good new is my engine is not blown. The bad news is, that I am still getting a code 27 after it idles for a while. I have trouble believing that the three MOP's I have used are all bad. They all pass the continuity tests, etc. So, I fear I have a long road of wiring tests in front of me.

If any one has had this happen to them (perfect idle, then a code 27), let me know your solution. I will be ordering a new Wiring harness for my MOP to eliminate that possibility.

MY CAR IS ALIVE!!!!------YAY!!!!
Old 07-18-02, 10:46 PM
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yay congrats!
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