Why did my ECU fry??

[Colt90tsi]

So I fried my ECU today and I am tryin to figure out why..

I am just finishing up my rebuild and come to find out I am firing on 2 cylinders, a bad coil... Also when it runs it is acompanied by a knocking sound, sounds like its coming from underneath intake mani.

I was tryin to fire it up today to post a vid on here with the knocking and it started up fine then died, all the sudden I smell it! Oh wow I couldnt believe how bad it smelt, so automatically I knew it was ECU, I pull it out to find a fried board. I am wondering if it fried because of the bad coil...

Also when I turn on my lights one head light pops up and the 10a tail feux fuse blows everytime, could this be it? And this first time the fuse blew I look under the hood to find a 30a fuse in the 10a place. WTF?!?

 

[VTEC_THIS]

You have a short somewhere that caused all of this to happen?

EDIT: What was this 30A fuse supposed to be for? For an aftermarket radiator fan or something else where too much current would be a problem?

 

[Colt90tsi]

You have a short somewhere that caused all of this to happen?

EDIT: What was this 30A fuse supposed to be for? For an aftermarket radiator fan or something else where too much current would be a problem?

Thats what I am asking. I obviously have a short causing the 10a feux tail to blow out, it the fuse that also controls your dash light. I was just wondering if that short would also fry my ECU.

Whoever owned the car before me put a 30a fuse in the 10a fuse's spot, maybe causing the ECU to fry???

Thanks for the reply VTEC_THIS

 

[Colt90tsi]

Also I was looking at where the knocking was coming from, the mid shaft bracket is loose, could this be the loud knocking sound?

 

[VTEC_THIS]

Gotcha. I'm sorry if you already posted this and I didn't understand... but where was the 30A fuse installed exactly?

As for your knocking noise, you say you hear it when the car is running... do you hear it just when the car drives or at idle as well? If it were just the bracket you would probably only hear it thump right after acceleration, at least that's what happened when mine came loose.

 

[Colt90tsi]

Its all good man, I think I made it sound a little confusing.

Anyways the fuse that I am talking about is circled in red. It is called tail/ feux air 10a, here is a picture:

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[cheap90gsx]

had a similar problem with my window fuses, the relay was fried or something. maybe a bad relay somewhere. didn't mess with the ecu but ECU's seem very sensitive.

 

[soulweaver]

I was reading some were and they said that 90 percent of the ecu's that were installed on the 1g sucked. So welcome to that 90 percentile buddy.

 

[z24frank]

Our Ecus arae know for having crappy capacitors.

 

[fwdmaster]

Our Ecus arae know for having crappy capacitors.

z24frank is right, might aswell upgrade to a eprom ecu,I have a 90 eprom ecu if your interested

 

[steve]

Post a picture of the ECU board. It may be the input filter cap that shorted or some of the driver chips that released the smelly magic smoke. If it was a driver then there is a problem with the car and it will torch the next ECU you put in.

 

[Colt90tsi]

Sorry double post..

 

[Colt90tsi]

Post a picture of the ECU board. It may be the input filter cap that shorted or some of the driver chips that released the smelly magic smoke. If it was a driver then there is a problem with the car and it will torch the next ECU you put in.

Exactly why I am trying to figure why this is happening, I dont want to fry another ECU. Man this thing smells so bad I have to leave it in the garage wraped in plastic bags.

Here are some pics for you.

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[steve]

The filter cap for the incoming power (C106) shorted and burned up. That's not a car problem. Totally avoidable waste of a non-EPROM ECU though. In general this isn't a repairable problem because the board is burned through. That ECU is only good for spare parts now.

Again a reminder to people to check your ECUs and replace the caps if they are original. They all need replacing. Some will fail like with some fireworks like this one others will leak and eat up the board but all of them will fail.

 

[Colt90tsi]

Thanks for your input steve. So pretty much I can put another ECU in a be good? Also what do you think caused this, old caps?

 

[steve]

So pretty much I can put another ECU in a be good? Also what do you think caused this, old caps?

I thought I answered both of those questions. The problem was bad caps in the ECU not something wrong with the car. Just make sure your "New" ECU has had the caps replaced.

That was a '91/92 MD166262 ECU. Is this for your '90 car?

 

[cumpersgsx]

i have an ecu for a 90...lmk if you need it. I also fix ecu's for people in my area. pm me if you need anything done.

 

[Colt90tsi]

I thought I answered both of those questions. The problem was bad caps in the ECU not something wrong with the car. Just make sure your "New" ECU has had the caps replaced.

That was a '91/92 MD166262 ECU. Is this for your '90 car?

I actually have a 91 that I am working on. Thanks for your help steve!