Your experience with bad ECU's

[3tcpower]

I have done some searching and nothing overly conclusive.

My question is, how many of you have had a bad ECU? What were your symptoms? Did you datalog?

I am pretty sure mine is "jacked" and just trying to get a good set of info before I rip anything else apart,

 

[DSM "BISH"]

well im my other post i have described my problems wiht my ecu. i dont really know why it burnt out but two circuits on the bread board have burned completly out so now i have to get another. im not getting anohter factory one however because my motor and the ecu that was in it before has been tuned on by the previous owner and i do not want ot mess that up by putting the stock ecu back on because the other one i have has a chip on it. but for fear of another stock type ecu buring out im just going to upgrade to my standalone aem ems. i really didnt have any symtoms pr anything to let me know that my ecu was going out. i started it up one night and let it waom up for about 10 minutes like normal and i got to the top of my street and i heard a burning sound and saw smoke cominmg from the ecu hten the car died. it still cranks but will not start now.

 

[kyleh]

Several things could be affected.
When my ecu was trash it took be awhile to figure it out.
Idle surge was really bad. I thought it was my ISC but after getting a logging and messing with that I noticed a lot of values where screwy such as my throttle position. So I got out the ECU and noticed that the board looked trashed in some parts. Getting the ecu out in the 1g is actually kind of a pain in the ass, I'm used to easy access to my ecu in my 300zx.
So I replaced the ECU and the car idled like a dream. I'm sure it helped out other things as well and no problems sense.

 

[steve]

I have done some searching and nothing overly conclusive.

I'm likely the most experienced person here on this subject.
If you looking for an exhaustive list of symptoms you won't find one simply because there is some random factors involved in how the root causes damages the ECU.

The #1 cause of failure is leaking capacitors.
#2 Bad ISC coil blowing the IC105 and IC107 drivers.
#3 People who have no business playing with electricity wiring up turbo timers, alarms, O2 sensors, and piggy back computers (user error).
#4 power surges. Bad alternators and dyslexic battery jumpers (user error).
#5 Removing solenoids and leaving the harnesses unprotected (user error). The wiring to the solenoids contains the signal wire to the ECU driver and 12v from the ignition or MPI power, shorting them will blow the driver on the ECU.

The most important thing a 1G owner can do is make sure that the caps are changed. It's not a matter of if just when are these going to ruin your day.

 

[SnowBird]

One I had that was bad would click like crazy at start up and the car would sputter real bad while it was clicking then it would go away and run. It kept doing this at start up getting worse everytime until it finally crapped out on me on the highway. It died like 4 days after it first started clicking.

Another one I had never "died" but my car wouldnt run unless I warmed it up completly, it would sputter and misfire if I tried to drive it without letting it idle forever. Even if I was driving it all day I would stop at a store for like 10 minutes and I would come out and have to let my car idle for 5 minutes even though it was completly warmed up. When I swapped in a new ECU this problem dissapeared.

Both of these ECU's were 90 non eproms.

 

[cheap90gsx]

with my experience the 90 ecu is more prone to fry from the caps. i switched to a 91 and didnt have any more problems.

 

[RayBan GST]

well i had a 97 gst before, Automatic and the ECU was burnt so i can tell you about some weird things that happened before i lost MY ECU


the rpm was jumping like crazy when i am at iDLE sometimes it reaches 5 K RPM

while driving the car the RPM WILL not drop down at all it stays there eventhough i change gear ( AUTOMATIC)

the last thing before my car died was a strong smell of fuel and the car was loosing power like crazy even though i had no leak or no other problems.

i took my ECU to a shop where they rebuild it by a computer system based on the engine requirements ( it took them 2 weeks to rebuild my ECU ) i did that because we dont have spare parts here for eclipse its very rare ( after they fixed the ECU my car was running perfectly )

i forgot i used to smell a burn smell from the ECU ALSO

good i sold that car after i fixed the ECU

 

[DSM "BISH"]

so one of my isc's burned out and a acpaacitor burned out but from what im reading here if i just replace my ecu wiht a new one i shouldnt have any problems?

 

[steve]

so one of my isc's burned out and a acpaacitor burned out but from what im reading here if i just replace my ecu wiht a new one i shouldnt have any problems?

No, you need to replace the ISC if it was bad before replacing the ECU or it will damage it.
The old style ISC's tend to go bad over time so it can happen again.

Unless the "new" ECU has had the caps replaced they will leak just like on the old one.

with my experience the 90 ecu is more prone to fry from the caps. i switched to a 91 and didnt have any more problems.

The 90 ECU do seem more likely to burn when the caps fail than the later versions but after replacing the caps I don't find that to be true anymore.

We've been talking mainly about 1G ECUs. The 2G Turbo ECUs don't have a problem with the capacitors leaking but still suffer from bad ISCs and loose nuts behind the wheel.

 

[DSM "BISH"]

well ive decided that instead of getting a factory style ecu im going to get teh aem ems but i still defintly want to get what ever caused the old ecu to burn out fixed becasue i do not want to destroy my aem unit . my car is a 93 with about 130,000 miles on it so it is most likely that since its old and been used that the capacitors did indeed leak the electrolyte as you were saying steve nad the burn out was becasue of both that and the bad isc so i want to test the isc and replace if need be.

 

[EVIL EAGLE RT]

My Ecu When To Shit When I Had The Engine Crankin But No Start I Had No Sprak Or Fuel,. Also Had No Power Going To Any Of My Sensors, Check The Mpi Relay And Was Good The Only Thing Before That Is The Ecu Which I Opened And A Resistor Was Fried.