Fried ECU

[Nautica985]

I have a 90 GSX and while it was idleing the engine just shut off by itself and smoke started pouring out of the ecu. I can most likely get a replacement one but before I do I wanted to know if this could of been cause by something other then the ECU. I just want to make sure so the new one doesnt get fried also. Oh and while I was driving earyler that day the ecu was making clicking noises every so often and all of the warning lights came on.

 

[Nautica985]

please help

 

[92redman]

I have had 2 ecu's go bad on me now, the one I am using now is screwed up on the barometric pressure signal. No other symptoms, it makes it harder than hell to do a cold start because the ecu thinks I am under 37 in Hg.

I think that maybe we could make a sticky about it so everyone can share their probles and any information they find out about the ecu problems, because so many 1g's are plagued with dying ecu's.

If anyone has found a way to test and repair the ecu itself, please share. New ecu's are just way too expensive.

 

[92redman]

Oh yeah, my first ecu started to fire only one of my ignition coils, causing a misfire in two cylinders.

 

[scottr126]

Nautica985, did u get a replacement ecu yet? ifso did it go in ok with no probs? because the exact same thing happend to me and i just wanted to make sure nothing else is messed up on my car. thanks

 

[RipperXX]

When the ECU starts clicking. Death is not far away.

 

[Thunderskull]

Originally posted by Nautica985
I have a 90 GSX and while it was idleing the engine just shut off by itself and smoke started pouring out of the ecu. I can most likely get a replacement one but before I do I wanted to know if this could of been cause by something other then the ECU. I just want to make sure so the new one doesnt get fried also. Oh and while I was driving earyler that day the ecu was making clicking noises every so often and all of the warning lights came on.

Yes it more than likely is. Your idle speed controller is directly connected to the ECU. When that goes, it can send an electrical surge into the ECU and fry it. The same thing happened to me, and the ISC is what did it. I replaced them both and have had no problems since. I'm attaching a pic of an ECU. The area I circled is what you would expect to get fried if your ISC goes out.

 

[scottr126]

yup that is exactly what burned up on mine, i think the burned one for me was the 2nd one up. but I bought a ecu now but I dont have a new isc yet, can I just disconnect the isc for the time being before i buy a new isc because I need to drive my car. What would the effects be of disconnecting it long and short term?

 

[Thunderskull]

I did that for a little while when that happened to me. You're going to eat up a whole lot of gas. Also, you're going to idle high at stops. Also, if that plunger is stuck all the way in, then you might have a problem with the idle being too low and the car dying on you. If I remember right, you can twist the plunger so that it goes back in. I'm not sure what the real long term problems could be from not running with an ISC. Www.crebotech.com sells rebuilt ISCs. You can pick one up for around $120 shipped. I got mine off ebay and it worked out fine though I would recommend a rebuilt one. I think I saw one on ebay for sale not too long ago.


Good luck.

 

[Nautica985]

Nautica985, did u get a replacement ecu yet? ifso did it go in ok with no probs? because the exact same thing happend to me and i just wanted to make sure nothing else is messed up on my car. thanks

The new one seems to be working fine but i havent really drove the car much cuz ive been having 1 problem after another. My alternator just went, i dont know if that could of caused the ecu to go. The part that fried on my ecu is the area around 47uF @ 50 and the chip right below it and to the right a little

 

[Thunderskull]

It sounds like you just had leaky capacitors. An ISC that's going can cause that , but if you had a 13 year old ECU I wouldn't be suprised if it was only the leaking capacitors. My car's original ECU fell victim to leaky capacitors. It was the one that I used to replace it that actually burnt up due to a bad ISC. I would check the ISC just to be on the safe side. Besides, an ECU with leaky caps can put some extra wear on the ISC. Vfaq.com has a section that will walk you through on how to test the ISC. It's pretty simple to do with a voltmeter.

 

[scottr126]

Alright lets see what all has happend so far for me, I installed a new clutch and went to go start the car (90 TSI AWD). It started up and ran good for like 30 seconds then it died and the ECU poured smoke. Then I Pulled the ecu and found that one of the things circled in the picture above was burned up so I ordered another ECU, put it in and disconnected the ISC so it wouldnt fry my ecu again and went to go start the car. it started up and idled at about 2k for a while then I gave it a lil rev and just stuttered alot from 2-3k but did rev, it ran ok for a little while but then overall the car ran shitty. But now it barely starts, i have to give it gas to start it or even just to sputter a little bit and its completely un driveable its so bad. Could this be because the isc is disconnected or what do u think?

 

[Thunderskull]

I had the same hard to start problem. This would be especially true on a chillier day. Eventually it would act like it was flooded if I had just driven it and then tried to restart it. Unfortunately, this was due to me using a replacement ECU that had been damaged. (Hey it was $60 on ebay) The problems became worse the longer I had the ECU in the car. I'd pop the ECU cover open on yours to see if it's damaged in any way or if it looks like somebody had tried to clean up some leaking capacitors. Did you get one used or refurbished?

 

[scottr126]

Alright I will pull it out and check it again. But when I opened it up when I first got it it seemed to be in perfect condition. Im gonna test the ISC today and see if its bad and replace if necessary and then Ill check out the ecu if its still not workin right.

 

[Thunderskull]

Sounds like a plan. Drop a line and let us know how it turns out. The ECU I received that I had the trouble with looked pretty clean until I took a close look. I saw that the capacitors had been replaced on it, and there were slight remnants of acid left on the board. In addition, there were a few black marks on the the riser card closest to the driver's side of the ECU board. Mine did exactly what yours is doing when I had that ECU in the car.

Good luck

 

[scottr126]

Alright well I opened up my ecu and it didnt look too bad. It was obvious that the capacitors were replaced recently, but they were all the same size, they were all about the size of then center one circled in the picture above. So I knew the caps off my old ecu were good so we swapped those ones in hoping for it to fix the problem. ALSO one of the white cards (the one right under the capacitors in the pic) had a little bit of black gluish type stuff on the top of it, but it can be wiped off..what would it be?

 

[scottr126]

Well anyway, I put the ecu back together with the new caps, and put it in the car. And the car wont even start now, it just cranks but doesnt rev, it does get gas though I can smell it pretty strong. Any ideas guys???

 

[Thunderskull]

Your ECU is toast. You need to get another one. The black gluish stuff is dried up acid from the capacitor. It's somewhat gluelike. If it got that far, then the caps were leaking pretty bad. The board's probably toast. The guy probably replaced the caps, found out it didn't work, then pawned it off. The acid probably damaged one of the chips on the riser card. You need another ECU. Don't feel bad, I went through 2 before I got one that worked right. Then I fried that one. When you buy used ECU's sometimes it's hit or miss. That's why I never pay more than $60 for a used one. I'll pay more for a refurbished, but not for a used one. You never know what you're going to get.

 

[scottr126]

Well that sucks but it does sound like your right. But since on my old ecu the caps didnt go bad but just the things circled in red in the above pic. Couldnt i take one of the black chips off the ecu I bought and put it on my old ecu to replace my burned one?

 

[Thunderskull]

You can try, but you have no idea what else is destroyed on your old ECU. Enough current went through it to burn up the chip on your unit. The leads going to the chip from the board are probably burnt up too. It's likely that other components on the board were damaged. The current has to go through a few places in order to get to that chip. I feel your best bet is just to go buy a refurbished ECU or try your luck with a used one.

I've been in your spot, and I know it's no fun. Good luck.

 

[scottr126]

Well I switched out that chip and sure enough......The car didnt even fire, it just cranked. SO now im in search of another ECU, but hopefully I can test it out before I buy it. Anyone have any Ideas where I could get one??? Or anyone selling one?????

 

[scottr126]

Alright guys I gave in and whent to autozone to buy a refurbed one. It was about $230 with a core. Ill let you know how it works out.

 

[blueman803]

What does the 47 @ 50 capacitor do? I took my ECU out and I am completely missing that capacitor yet my car runs fine. There are signs of leaking capacitors and a few burned spots on the board. The AC relays are not getting power, and that is what lead me back to the ECU. Put other ECU's in and they short and do not run the car at all. What could could cause this problem?

picture
http://www.dsmtuners.com/gallery/data/500/22982100_08472-med.JPG

Green indicates burn spots and red indicates completely missing capacitor WTF

 

[91dsmeclipse]

i know my ecu is toast i just cant find a replacement anywhere i went to every junk yard for one no one has one i even went to auto zone and they dont have my make of ecu so what i did i opened the ecu up and cleaned all the acid from the caps and anything that looks like burn markes i have to clean it once a month or once every 2 months but i havnt had a problem with anything since ive been doing it as soon as i hear the mpi relay clicking and just take the ecu out clean it and its all fine for another month

 

[SexperT]

You ECU dies aswell if you leave the switch to start the car open, a dsm wiseman told me this once.