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Engine Electrical issues still

1K views 11 replies 4 participants last post by  LostPawn 
#1 ·
I've been battling some electrical issues lately and they still seem to persist and change, looking for next steps. I installed the BOE Torque 300 tune to my '07 Exige over the winter along with the smaller SC pulley, bigger injectors, and CAI. After the install the car ran good and was issue free for just over a month. Then I started to have injector issues (one was a simple pin not seated well in the harness) and another kept throwing an Injector Circuit-Cylinder 3 code. That would go away after the car sat or cycled through a power off, usually I'd pull the SC off to inspect wiring and put it back together and it would run fine. That's when I took it to 3R Racing to look into it further, they worked with BOE and the next logical conclusion was a bad ECU (huge thanks to Phil for all the help so far). I got another ECU installed and all seemed fine again driving around a few blocks and for 1 track session. The second track session the engine cut out kind of, odd sound almost like the rev limiter and different then when injector cylinder 3 faulted. I have no CEL and no pending faults at the moment. After shutting the car down for 10 minutes, I was able to drive off the track and it seems fine but I have not pushed the car again yet. It was very windy so the sound is not great, but the first few seconds and last few seconds you can hear the engine sound I'm referring too. My data didn't seem to record so I cannot check if temp suddenly dropped or what might have happened. Has anyone heard this sound before and if so what might the issue be?

 
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#2 ·
I have, exact same symptoms, my problem was the OEM part of the harness to the injectors was rubbing on the intake manifold and had rubbed through and grounded. I have also had similar symptoms when my coils were really old, but it was very intermittent.
 
#3 ·
I'll check the harness again (4th or 5th time now) but didn't see any insulation rubbed but I'll check. Gator was looking into getting me a new harness but seems they are not currently in stock.

We swapped coils around when the CEL for cylinder #3 was the error code and it stayed with the same cylinder, but if I'm just throwing parts at it now I can get new coils too.
 
#4 ·
So few things

1. MWR has new and used harnesses in stock as of a few weeks ago.
2. The problem never moved for me either, Phil seemed to think that the codes aren't especially useful.
3. You can get a set of coils off amazon for $70 and I have run them for 2 weekends now. Maybe they wont last forever but a great diagnostic tool.
 
#5 ·
MWR does have a used harness but I do not see a new one for the SC Exige, and the used one is more than a new one. Radium has the connectors if I really wanted to build my own harness but not sure I'm at that point yet. They do have the coils and I'll start there unless another inspection of the wires leads me to ordering a harness.
 
#6 ·
Just guessing
Do you have a cutoff switch? A friend had one and the car kept cutting out momentarily on left turns. Turned out the switch was cutting off power, and then the ECU was going on like nothing wrong.
Also, have you checked the wiring for chafing on sharp objects? Or other loose connections? (didn't see the other comments yet)

My nephew works at 3R btw.
 
#7 ·
I do have a cutoff switch and had not thought to check that but I will now. The cutoff switch is also new this year but have not double checked it.

I have looked at the wire from the ECU to the injectors and coils, I believe 3R did as well along with testing the wires. I was told they did so both cold and hot.
 
#12 ·
Make sure you take it apart, clean all the surfaces, and make sure that the bolt is actually bottoming out on the ground, not on the end of the threads.
I've cleaned that ground and a couple others and still have the issue. I swapped in new coils and did the dielectric grease, that didn't solve the issue either. I was finally able to get a CEL for a pending injector circuit cylinder 3. That is the same code I had before the ECU swap too. I've pulled the ECU connector off and it seems I need a pin to test for friction, happen to have an extra one? How do I dissemble that connector if I do need to replace a connector in it?

Anyone happen to have a diagram for that connector? I've seen a diagram for the '05 ECU harness but not finding one for the '07 drive by wire.
 
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