Electrical issue. Help a brother out with some questions.

[broxma]

The car does run. Sounds like it's running on two cylinders. Has fuel pressure, etc, all normal things have been checked and double checked. The car uses an EVO ECU of which I have two and both present with the same issue and both work in my Evo. It's not the ECU. It's not a ground. It's not a single sensor.

What it is...

My car has been dead for about 3 weeks now and I am in the process of stripping the entire ECU harness apart at this very moment. The car has presented with multiple codes which seem only partially related. These range from P0183, P0122, P0335, P0340 and then several "P0 0", "P1 2", "C1 3" which are a total mystery to me. I also get codes from the ECU for things like Fuel Temp sensor which we don't even have.

I'll start with a question which I think is at the root of it. It runs a COP ignition through the factory DSM ignitor. I swapped the ignitor with a known good. With either ignitor, the #1 and #4 coils heat up, to the point they would burn you if you left your hand on them, with the key in the on position. Not running, just the on position. What would cause the coils to heat up this way?

Second question. It is reasonable to assume that no dedicated positive wire should have zero resistance to ground? Would this be an accurate statement?

Third, could a problem in the cabin harness cause these codes at the ECU? Since the two harnesses are essentially separate from each other, and every electrical item inside the car works fine, lights, belts, headlights, gauges, everything, is it even possible for the two harnesses to affect each other in the way I have described.

For now, that is all. For the record, I posted a similar question on EvoM and have not a single response, mainly because I believe it is filled with a very small percentage of people who know anything at all and a large percentage of kids who just play bolt on racer.

thanks guys

/brox

 

[SouthCaliVR4]

I can answer two without more info. yes a pos wire with no resistance to ground is a short. And it is very unlikely that the body harness is causing your issue.

do you still have the parts to remove the cop & return the coil pack & wires. if so try that before you dig too deep & if your problem still exists it will be a much easier task to source your issue then you can return to the cop set up & see how it goes. I recommend that for two reasons, 1st cop set ups tend to be unreliable & two it will be a much simpler task to identify your problem with the stock ignition over the net.

 

[broxma]

Let's assume for a minute that the issue is with the COP ignition which up till recently has had no issues. How would this be affecting all these other sensors? And why would the coils heat up without spark trigger?

For reference, with a fresh battery reset on the car, it pulls code p0122(TPS). Once I start the car it starts piling the codes up. Somehow, all of this has to be related to a single point failure.

/brox

 

[broxma]

I mentioned that in the first post actually. Two Evo ECU's and both work fine in my Evo.

Doing some deductive reasoning I am going on the belief that for the 1 and 4 coil to heat up under static conditions there must be a short to ground on the hot wire leading specifically to one of those coils since they are driven by the same wire off the ignitor. If the positive is grounding out it would essentially force them into an always on condition. This positive would also create issues with any other component touching the head as the entire thing would essentially be hot/grounded all at once.

/brox

 

[SouthCaliVR4]

If you have a short in your cop system it can & will blitz your ecu. enough amps drawn by a problem there can cause the ecu to suffer erratic voltage issues resulting in meaningless codes. you already have good reason to suspect a problem in your cop set up & swapping it back to stock will let you know if your chasing real issues or sympathetic ones. in other words, process of elimination.

 

[524of1000]

Hmmm... Sounds like when the COP setup was put back on after checking for spark, one of the wires *may* have been pinched between the head and the plate and is grounding itself out. That would explain why it's throwing codes for all the sensors that are ahead of it in the line and why 1 and 4 are heating up. /ubbthreads/images/graemlins/devil.gif LMAO thanks for the help today man.

 

[SouthCaliVR4]

Glad to be of help.

 

[broxma]

So pretty much what Steve said. One of the two power wires to the COP got smashed between the plate and the valve cover. It didn't actually expose any wire but the repeated signal worked a small hole through it and melted the surrounding plastic cover on the wire. Since with the Evo ECU the grounds for the TPS, Crank, Cam and FP temp sensor are all on the same pin off the ECU, it coded for all of them. The "P" and "C" codes were for Chassis and powertrain non-specific codes related to the circuit being pushed through the head.

I took the COP off, replaced the #1 and #4 coils since I was worried about any thermal damage, rewired the COP and reinstalled. After I was done wrapping the ECU harness and plugging in a connector I forgot, it fired up.

Neither of the ECU's were damaged at all even though both were used when I had the short through the head.

Thanks for the help guy who's name I don't know.

/brox

 

[SouthCaliVR4]

Its Geoffrey, good to hear you found the problem & again glad to be of assistance.

 

[Hertz]

Nice work!