Hey guys while doing my 60mm tb install I noticed my wiring harness for my injectors had burned through right to the copper and the copper was exposed for injector 4. The car was sputtering and an CEL had came up when I fired it up so i took it to a shop and it came up as cylinder 4 was not firing. Mechanic said it must have shorted out and fried that section of the ecu after he used his tester. Does this seem legit to happen or should I get a 2nd opinion? Hence why I am asking all the pros. If thats the case I guess a new ECU is in store? I had a 2nd wiring harness for the injectors lying around so I tried that and same issue still.

Would the injector itself get fried before the ECU? Thanks again.

BTW its for a 1999 eclipse gs. Thanks in advance.

The EFI/ASD fuse would have popped more than likely before the ECU. There are failsafes for that reason. Get a second opinion.

Yea it sounds unlikely to fry the injector circuit in the ECU. I know they make testers that will show you if the injector is firing or not, I have seen them made out of 1 LED and a resistor, might want to try something like that before you go buy a new ECU.

Where are those fuses located? How can I check if one of those has popped?

Also he used a tester from the battery to the injector wire it was showing a power but no neutral ( or negative?) Thats why he said it was the ECU. Does that make sense? I'll go to a different mechanic tomorrow anyway.

Yes that makes sense, the injectors get power from the same wire, then the ECU 'fires' each injector by grounding the other side of the injector. I would check for continuity between the ECU pin and the injector plug. You can find ECU pinouts on this site.

So my new ECU came in off an 1998 gs and i switched it and the car works fine now. Idles better than before at about 900-950. What I learned : Exposed copper from the injector pigtails will cause an electrical short and fry a part of the ecu!

My question is for the plastic and insulation off the wire to melt the way they did, should I be concerned of it happening again?

Time to try that 60mm throttle body mod again. :)