"Electronic Brain" (ECU) replacement

[revbill]

Hi, all. I'm a frequent lurker (and information user) but I don't post much, thanks to the hefty archives on this site, which are better than any repair book I've ever seen.

 

I'm a contractor at Microsoft, and there's a '91 Loyale someone's looking to get rid of cheap in the Microsoft classifieds. In the ad it says it needs an "electronic brain." I e-mailed the person with the car, and they said their neighbor, who is a mechanic, came up with this diagnosis when the car died and wouldn't start. I'm not sure if it turns over or not, but it sounds like it might.

 

My question for you all is, first of all, has anyone looked at this car? It's been in there a while, and I wouldn't be surprised if there was another subaru maniac working at MS.

 

My other question is: what should I look for if I go look at this car? I was going to bring a battery and see if it turns over, then go from there. What would the symptoms of needing an "electronic brain" (I love the way this sounds--great band name) be? It sounds like if this is really the problem it would be pretty easy and cheap to fix, but would there be a risk of blowing a new ECU?

 

One theory I have is that the timing belt broke, and the well-meaning neighbor was explaining that with these modern cars, everything's controlled by a computer, so they're hard to work on. It doesn't make sense to me that an ECU would blow on a perfectly good car, but who knows.

 

Does anyone have some advice for me on this? I appreciate all the collective help, past and future.

[zyewdall]

I've never heard of the ECU dying, unless the car is struck by lightning or something. Or if you try to jump start it and hook the battery up backwards. I suspect some sensor or such went bad, and the ECU won't let it start now.

 

But, if you do need a new "brain" for it, I'm parting out a '91 Loyale right now. I already used the engine, but no one has taken the ECU yet... That would be pretty cheap to mail I suppose. But where is it in this car? I don't see it under the hood anywhere. Maybe under the dash?

[Snowman]

Generally, if the check engine light comes on with the ignition on and the engine not running, the computer is okay. Your timing belt hypothesis is very likely to be true, and can be verified quite easily. The same procedure will also allow you to check for another common problem, which is the distributor rotor set screw coming loose.

 

Use a phillips screwdriver to remove the distributor cap (it's held down by two screws). Inspect the disty rotor to see if it's firmly held in place and unable to rotate on the shaft. If it can rotate on the shaft, then its set screw fell out. Reinstall the screw with some loctite and you should be good to go. If the rotor is firmly held in place on the shaft, crank the engine while observing the rotor. If the rotor doesn't turn with the engine, the driver's side timing belt is gone (that's the one that usually fails first). Replacing the timing belts is a simple job on these engines.

 

Good luck!

[Snowman]

I've never heard of the ECU dying, unless the car is struck by lightning or something. Or if you try to jump start it and hook the battery up backwards. I suspect some sensor or such went bad, and the ECU won't let it start now.

 

But, if you do need a new "brain" for it, I'm parting out a '91 Loyale right now. I already used the engine, but no one has taken the ECU yet... That would be pretty cheap to mail I suppose. But where is it in this car? I don't see it under the hood anywhere. Maybe under the dash?

 

It's held to the bottom of the steering column by three nuts.

[zyewdall]

Thinking about it, the timing belt sounds the most probable. They do fail exactly as Snoman says -- drivers side going first. And since the engine doesn't self destruct, it just stops running and you don't know why... Till you check the distributor. On mine I could also tell it was cranking weird, because it didn't have compression in one side any more.

[revbill]

Great, thanks everyone. I'll check the distributor and the timing belts when I go there. I thought it sounded strange that an ECU would go out. I'll be sure to ask if it was hit by lightning, or some sort of secret government death ray.

 

And zyewdall, I'll let you know if I need that ECU, thanks.

[calebz]

I had an ECU go up in smoke a couple years ago.

 

CEL wouldn't come on, got no spark and the fuel pump quit.

 

With the diagnostic connectors connected, the fuel pump should cycle off and on.. mine didn't. that was my first clue that something was not right.

[gunslinger]

Great, thanks everyone. I'll check the distributor and the timing belts when I go there. I thought it sounded strange that an ECU would go out. I'll be sure to ask if it was hit by lightning, or some sort of secret government death ray.

 

And zyewdall, I'll let you know if I need that ECU, thanks.

 

REVBILL,

 

if you decide to not pick the car up, call me and ill take it off the guy's hands. 425 478 8119. and if you need an ECU go to pullapart in lynnwood. ECU's under the dash bolted to the steering column.