ECU or wiring issue

Discussion in '94-95 5.0 - Specific' started by swhitcomb, Jun 27, 2014.

  1. swhitcomb

    swhitcomb New Member

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    Ok. I had been posting on the facebook group about this but I know that is really not the place so I will continue here. Here is what was wrong and what I did.

    It is a 1995 Mustang GT with a 1998 Explorer motor in it. X-pipe, CAI, cam and head work. It has the GT40 heads and intake. It is also running Moates QH and Binary Editor.

    So it had been running super rough when cold, backfiring and bogging down, then this started to happen when it was warm as well.

    Previous owner cut and spliced the engine wiring harness at the block at the firewall, the TPS and the O2 sensor pigtail. Car had the ICM and air temp sensors disconnected.

    Connected the ICM and then started getting a nasty moan from it at idle, thought maybe the TPS so I tested it with a voltmeter and it checked out.

    Thought maybe wiring issues with the sensors so I found a nice harness on eBay and bought it then installed.

    Car then would not start, discovered that I had forgotten to tighten down the CAI and still no start.

    Pulled the ECU and noticed that I had bumped the QH loose from the ECU. Reset it and nothing, removed it and it would start but not idle.

    Felt like I was getting somewhere, turned in the screw on the throttle body so I could trouble shoot and figure out what was up with it running.

    Tried reconnecting the QH and no change, it would run just like before and QH would not pull any data while running to the dashboard in BE.

    Someone suggested timing, I thought that couldn't be it, I didn't touch the dizzy. Went ahead and attached a timing light and the number 1 was firing randomly not in any sort of pattern, huge misfire issues. Also, I could notice the sound of what was the injectors that I had never heard before. Car is smoking from exhaust, never did that before either.

    Another post to the FB group and it was suggested the PIP might be bad. Ordered a new dizzy from AM and installed it.

    Found the timing marks and started car. Was able to set it at 10 degrees and then remembered that I need to pull the spout, pulled it and car died right away, put it back in and car started right up. Running rough and smoking, still hear the injector noise as well.

    I am at a loss with this. I am now thinking that either i fried the ECU or I have a bad harness.

    Any suggestions on the next step?
     
  2. rz5.0

    rz5.0 Legend

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    So your running a 98 motor. Was everything swap over from the 95 to the 98 motor. . You should redo your timing. . Start by restabing the distributor. .
     
  3. mikey94gt

    mikey94gt Well-Known Member

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    Sounds like you have multiple issues. Let's start at the basics. Do you have a check engine light? And if you do, do you have codes? What I am trying to accomplish with that is a test of the whole Efi system and let it tell us what's wrong. Also, how are the splices done? Soldered? Or are they butt splices? If you have doubts, post the pics. Last, check and see if your engine is grounded to the vehicle, that's pretty important, I've had issues with that before. Last thing, it sounds like you're running the stock ecu... Correct? Stock wiring?
     
  4. toyman

    toyman Active Member

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    Let's just deal with the timing. Forget for the moment about reinstalling the distributor. You say it will start with the spout in. Now rev the engine to about 2500 rpm. The timing should read about 35* BTDC. If it's more or less then adjust the distributor until you see 35* (it will move slightly as the ECU adjusts). Turn off engine pull spout and restart. The timing now will be steady (spout out) and should be close to 10*. If it's between 10-14* that's okay.