Resolved 1G Idle Problem. Shorted ECU?

[emd645e3]

I took out my ECU because I'm having an idle problem, and I narrowed it down to that. I was looking at part of its case, and there is a spot on it that kind of looks like a scratch, and there's a lot of discoloration on it. It looks like something shorted out on it.

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Sorry for the quality, but its the only camera I had. Just wondering what you guys think.

 

[blackbyrd]

Did you open up the ecu to check out the components, capacitors, and the board? How did you narrow down your idle problem to your ecu? where is this discoloration on the case?

 

[emd645e3]

Yes, I opened it up to check the components. They all look ok, but I can't really tell bad from good. I narrowed it down to that because there are no boost/vaccuum leaks, and I put in a new ISC. The discoloration is on the upper part of the case, on the inside.

 

[blackbyrd]

I dont know how much id look into the discoloration. i'll search around, but i know on both of my ecu's they have a pinkish/bluish random discoloring. Check for discolorations on the circuitboard. Look at your capacitors, the three cylinders in the middle of the board, look underneath them, around them for discoloration or some gu. There really isn't much for the inside of your ecu to short out on your ecu. And being securely fastened i dont see how it could flex or come in contact with something to do that.. But i'd really study the ecu good, and if you still cant find any visible damage, if you know anyone else with that ecu to swap out and see how it runs. What idle problems are you having btw?

 

[emd645e3]

It surges every now and then, calm down, and It'll run fine at like 900-1200 rpm then just die. It knocks a lot when it surges or if i rev it to like 2000-3000 rpm. It also runs rich. Mind you, there are no mods on it.

 

[emd645e3]

There is goo on one of the smaller vertical boards. Its on the one right next to the smaller capacitor. Otherwise, they look ok.

 

[blackbyrd]

hmm could you get a picture?

 

[emd645e3]

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Thats the best I can do. Its the middle vertical one.

 

[blackbyrd]

I really can't see much goo past the blur, heh. you wouldn't happen to know someone around you, that you could swap ecu's with real quick?

 

[emd645e3]

Nope. I'm the only 1g guy around here.

 

[laserfrog]

DId u try replacing your O2 sensor, I read a forum today that said the computer will only check the o2 sensor if you have been going 45 miles per hour for more than 20 minutes straight. so it might have failed or failing, but the computer hasn't picked up on it. could be why u are running rich.

good luck
laserfrog
aka kris

 

[laserfrog]

I forgot to ask what engine is in it. I have a 1g 92 laser with the 1.8, and when i bought it it came with an extra computer. I am out of town for a couple of weeks, but when i get back i can plug it into my car make sure it works and send it to you if you would like. I will email you or post when i get back and see if you have had the problem solved yet or not.

Kris

 

[steve]

The white vertical board will have a goo in the center. Don't touch it. There will also be goo on the knock board on the upper right corner (holding the ECU with the edge connector facing you)

This a '90 style ECU board. What are the numbers off it on the case, edge connector, and above the two together caps?

Steve

 

[emd645e3]

I forgot to ask what engine is in it. I have a 1g 92 laser with the 1.8, and when i bought it it came with an extra computer. I am out of town for a couple of weeks, but when i get back i can plug it into my car make sure it works and send it to you if you would like. I will email you or post when i get back and see if you have had the problem solved yet or not.

Kris

No, its a 4g63t.

The numbers-

Case: MD128625
E2T34474
9X17 A

Edge Connector: 4474A

Above the two caps: JE331A979A (The "1" may be an "I")

 

[blackbyrd]

So you have a 1990 FWD ecu in a 1991 AWD.. I believe you need to have pins 6 and 14 swapped? which would be your mas and idle position sensor.. good luck! hopefully that fixes it

Edit: vfaq http://www.vfaq.com/mods/ecu-harness-1G.html

 

[emd645e3]

Yea, I ran the numbers and it came back as a '90 ecu. I'll be switching the pins ASAP. Thanks guys!

 

[blackbyrd]

No problem! let us know how it works out!

 

[emd645e3]

I was lookin at the connector, and the green/white wire is on the #6 pin, and there is a green/red wire on the #14 pin. Is that correct figuring a 1991 ECU should be in there? Also, just to be sure, in the picture on the connector in the link above, is that viewpoint looking at the pins or the wires?

 

[steve]

Just to be sure, in the picture on the connector in the link above, is that viewpoint looking at the pins or the wires?

The pins are referenced to where they go into the ECU connector.
The is what the VFAQ and manuals are trying to show you.

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The mating connector from the harness is then numbered looking at the back of the connector where the wires come out. Ignore the missing wires I've stolen from this connector.

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Steve

 

[emd645e3]

Ok, thanks!

 

[emd645e3]

Did the 6 and 14 swap. She runs like a dream now! Just have to get a new transfer case........