The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support ExtremePSI

2G Pretty sure I have a bad ecu

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

KSnippy

Proven Member
42
0
Jul 24, 2016
Marietta, Georgia
I've been having problems getting my car to idle, I'll post a link below. I did a smoke test and didn't find any leaks but I have yet to do a boost leak test, my compressor is broken. I pulled the IAC and tested it. It looks to be a newer mitsubishi unit and I got consistent 40 ohm readings on it. Everything I read about said it would show 30 ohms but I got 40 and I'm not sure why. I pulled the ecu and am pretty sure the idle drivers are shot. I guess from where the IAC went out. The damage doesn't look as bad as some examples I've seen but it looks like the damage is done. When looking for a replacement ecu do I have to get one for a 95 96? Does it have to be eprom? What do I need to look for? I've attached a few pics of the ecu for reference.
You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

Idle video
You must be logged in to view this image or video.
 
Thanks for the link joejoe. I remember coming across that site while doing research but just glanced over it. After reading it though that explains why I'm getting 40 ohms. Looks to be a revised unit. Also caugh my attention about the FIAV seal leak problem. I noticed mine has dried coolant on it when I pulled it. Guess I need to tackle that do. I do know my car had a blown head gasket at one time so that could have effected the seal.
 
Those are blown ISC drivers. I had that happen but a little worse, I'd say it took out about 3 drivers (see top right of pic). I sent ECMtuning that ecu with link installed + another perfectly good ecu from the project for caps and ECMtuning recommended (to me at least) that the damaged ecu is not worth fixing because the drivers are expensive and not so abundant. So I had them just swap link to my other ecu w/ new caps of course. BTW the guy I bought link off of had terrible idle problems and couldn't figure out why:ohdamn:
You must be logged in to view this image or video.
 
I plan on just finding a used unit online. I was just going to look for another 95 96 ecu but I didn't know if I could use any other years. Eprom isn't that big of a deal to me but I'd prefer it just in case I look for bigger power later on. Going rate seems to be about 100 bucks so that doesn't seem too bad.

Secondly should I be concerned about the coolant on the IAC? Could this be front the head gasket blew? I'd hate to replace the ecu just to have a leak blow the iac and blow another ecu. Is a fiav leak very hard to diagnose or repair?
 
Update

Well I got a replacement ecu and i was right the idle drivers were bad in the old one. The iac now moves and work. Unfortunately I'm still having the same idle problems. I guess the next step is to try a boost leak test in hopes to find something.
 
Welcome to the bad ECU club. I just joined this club myself. I am in communications with ECMLink to see if they have one or more solutions for me.
 
stuff like this makes me wonder how many milliamps it takes to pop the driver when a bad isc presents itself. a fast reacting polyfuse might be an effective stopgap measure.
 
You can calculate the normal current based on typical electrical system voltage and the ISC coil resistance and look at the data sheet for the drivers to see their max current specs. I think you'll find that a short will destroy the driver IC faster than any polyfuse will react. You should also look at how much added resistance might effect the ISC stepping.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top