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Motor runs rough. Any ideas?

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Old 09-15-05, 12:12 AM
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Motor runs rough. Any ideas?

I drove my car into the garage. The car was running fine. I replace my turbo oil feed line. When I was finished, I tried to start the car, but it wouldn't fire. I found that I broke a wire going to one of the crank angle sensors. I fixed the wire and the car now fires. I runs rough and it sort of sounds like it's running on one rotor.

I've tried a couple of things to fix the problem:

Replaced the engine wiring harness
Replaced the plugs
Replaced the plug wires
Checked compression
Checked the resistance in the crank angle sensors

Anyone have any ideas?

Thanks so much.
Old 09-15-05, 12:36 AM
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Could I have a bad CAS?

Or perhaps a bad coil?

Thanks again.
Old 09-15-05, 01:01 AM
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Originally Posted by Bodyshop
I drove my car into the garage. The car was running fine. I replace my turbo oil feed line. When I was finished, I tried to start the car, but it wouldn't fire. I found that I broke a wire going to one of the crank angle sensors. I fixed the wire and the car now fires. I runs rough and it sort of sounds like it's running on one rotor.

I've tried a couple of things to fix the problem:

Replaced the engine wiring harness
Replaced the plugs
Replaced the plug wires
Checked compression
Checked the resistance in the crank angle sensors

Anyone have any ideas?

Thanks so much.
I would guess it still has something to do with the crank angle sensor but try resetting your computer first. Unplug your battery and let the car sit for a minute or so, press on the brakes a couple times, reconnect the battery and try and start it.
Old 09-15-05, 07:21 AM
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Ohh ya. I guess I should list my mods:

GT35R single turbo
1600cc secondary injectors
factory primary injectors
Apex-i Power FC
No emmisions
No power steering
No A/C
Koyo Radiator
Apex-i AVC-R

That should cover the basic engin mods.
Old 09-15-05, 07:22 AM
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Originally Posted by Mr rx-7 tt
I would guess it still has something to do with the crank angle sensor but try resetting your computer first. Unplug your battery and let the car sit for a minute or so, press on the brakes a couple times, reconnect the battery and try and start it.
I had the batterey unhooked for the entire time it took to replace the engine wiring harness.
Old 09-15-05, 07:54 AM
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are you sure you havent got crank ankle plugs on wrong way round (theres 2 sensors) when i rebuilt my engine i plugged them on wrong way and my car run rough.
Old 09-15-05, 09:04 AM
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Originally Posted by tiger18
are you sure you havent got crank ankle plugs on wrong way round (theres 2 sensors) when i rebuilt my engine i plugged them on wrong way and my car run rough.
I tried switching them around. When I did, the car wouldn't start.
Old 09-15-05, 09:23 AM
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Have you tried checking the vac lines? Maybe one got loose or unplugged when you were working on the turbos or the crank angle plugs. Just a thought.
Old 09-15-05, 09:24 AM
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interested also. mine has this same problem. my problem is off and on though. my map sensor reads - 45 mmHG when the engine is off. no vacuum tanks since im non-SEQ.

what does your map sensor read when the engine isnt running?
Old 09-15-05, 09:29 AM
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check to see that your map hasn't been erased on the pfc
also ohm out the ignitor and coils

sounds really frustrating!
Old 09-15-05, 09:44 AM
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To reset the ECU, you not only have to disconnect the battery for a while, you have to hold the brake to discharge its memory. But I don't know if that applies to a PFC at all.

The roughness could be a bad coil or maybe a sticking injector.

But first, you didn't say if you had tried a thorough unflooding procedure. Then once you get it running solidly, put in a fresh set of plugs.

Dave
Old 09-15-05, 10:49 AM
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Originally Posted by yuichiror
Have you tried checking the vac lines? Maybe one got loose or unplugged when you were working on the turbos or the crank angle plugs. Just a thought.
I have checked all the vac lines and the CAS plugs

interested also. mine has this same problem. my problem is off and on though. my map sensor reads - 45 mmHG when the engine is off. no vacuum tanks since im non-SEQ.
I'll check my map later today.

check to see that your map hasn't been erased on the pfc
also ohm out the ignitor and coils
I know the map hasn't been erased. I have the same problem if I pug in the stock ECU. How exactly do I "ohm out the ignitor and coils"?

Thanks for the help so far.
Old 09-15-05, 12:40 PM
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If you have the workshop manual it tells you how to test all of those parts. I forget exactly how as it was kind of an unconventional method
Old 09-15-05, 02:29 PM
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have you checked the crank angle sensors with a testing meter,,,, im only saying this because my car run with angle sensors on back to front (but ran really rough,, and cut out),, but when i figured out they where plugged on the right way car ran great... get testing meter on them angle sensors,,,,make sure they spec out
Old 09-15-05, 04:18 PM
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Did you check to see if you have spark to all 4 of the plugs? I would check that and go from there.
Old 09-15-05, 04:45 PM
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Allright. I will have all 3 new coils here along with the coil harness tomorrow. I checked the crank angle sensors and the resistance is within spec. After I replace the coils, it souns like about the only other thing it could be would be the injectors.

I'll let you know what happens.
Old 09-16-05, 09:04 PM
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We replaced all three coils and the harness that goes to the coils. Still no change. We checked the resistance of both CAS and they check out fine.
Old 09-17-05, 02:47 AM
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Originally Posted by Bodyshop
I drove my car into the garage. The car was running fine. I replace my turbo oil feed line. When I was finished, I tried to start the car, but it wouldn't fire. I found that I broke a wire going to one of the crank angle sensors. I fixed the wire and the car now fires. I runs rough and it sort of sounds like it's running on one rotor.
10 bucks to two it was something you did when you fixed the oil line. Check the thermo sensor and also the the boost sensor on the firewall.
Old 10-11-05, 12:13 PM
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Has this been fixed? What was the problem?

Thanks
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