ECU Problems?

Technical and Repair Discussions

Novice Typer
Novice Typer
Posts: 22
Joined: Sun Nov 19, 2017 1:35 pm
PostPosted: Mon Apr 30, 2018 1:41 am
I've been battling some strange things going on with either my ECU or wiring harness ever since converting to Gen 3 this past winter.
I 've successfully run the car at one race weekend in April, but now new problems are arising.
Prior to racing the car and after conversion, I had battled a no start/ difficult to start issue, compounded by unknowingly mis-wired my ECU/ rain map circuit by following an incorrect wiring diagram. This no start issue was simply corrected with a new set of spark plugs, however why the plugs got so (fuel) fouled is a mystery. Chicken and egg situation.
Current symptoms:
1) Codes 12, 13, 14, 15 flashing on ECU warning light
2) ECU data to AIM MXL dash (coolant temp. and oil press. ) erratic or no reading
3) ECU data to AIM data logger dropping out to zero (in left hand corners only?), SRF ECT, SRF Oil T, SRF Oil P
Simply wiggling the ECU plugs or turning the ECU itself from side to side cause the dash data to fluctuate wildly of disappear altogether. I opened up the connectors checking for moisture or anything obvious and saw nothing.
4) engine running rough, and smoky exhaust , or starting and then dying.
5) unable to connect laptop to PE monitor Windows 10, will not find ECU. I've looked at my firewall setting on my laptop and don't think that is the problem. The PE monitor had been connecting to my laptop, but became unstable, and then soon after would not connect at all.

I've spent endless hours trying to solve this problem, and now they seem to be compounding themselves. Looks like I'll be heading for the next race again not knowing if the car is going to run.

I was hoping that SCCA E could provide a good known ECU and or harness for testing, but seems that is not in their protocol.
Anyone had similar fault codes come up?

Forum Hermit
Forum Hermit
Posts: 155
Joined: Tue Dec 06, 2011 12:26 pm
PostPosted: Mon Apr 30, 2018 5:45 am
If I remember correctly I was told- There was something about the cable between your laptop and the ECU being a special cable, it looks like a simple LAN (Cat5) but it's not and a regular LAN (Cat5) cable will damage the ECU.

Can someone confirm my hazy brain.
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Ready to Write a Book
Ready to Write a Book
Posts: 71
Joined: Tue Dec 06, 2011 9:54 am
Location: Conway, NH
PostPosted: Mon Apr 30, 2018 8:09 am
We had an intake manifold that where the map sensor is mounted in it the port that it sits in had not been punched out and was closed. This created negative pressure and ecu went very rich. The running problem / hard start you describe is exactly what we had-

Novice Typer
Novice Typer
Posts: 22
Joined: Sun Nov 19, 2017 1:35 pm
PostPosted: Wed May 02, 2018 1:16 am
I think I found the problem.
When I had been testing for my no-start /wiring issues previously, I had used a piece of safety wire as a probe into the ECU connector plugs. Inadvertently I suspect I stretched out the female pins so that they became loose on the ECU male pins. This seems to have had a snowball effect of loosing connectivity of the PE monitor, data acquisition problems, and possibly the ECU fault codes.

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