Hard Starting question. . .

[Junkyardslug]

Hi everyone. This question is about my Girlfriends 94 Legacy Wagon. When the car is Cold it takes about 20 seconds for the motor to fire. It spins and spins, and when it catches, if she doesn’t give it enough throttle to get it up to 3000 RPM it dies.

Now I know this is not good for the Car, I have rebuilt Motors, Automatic Transmissions, transfer cases, ect but she won't let me touch her car. Her loss I guess. So instead of letting me tinker with it, she takes it to a mechanic who told her it was her Computer. What do you guys think about that???

I don't know what all this mechanic has done to the car as far as diagnostics or sensor replacement. The car does throw one code for the Charcoal Canister sensor, but that wouldn't have anything to do with this would it?


Her mechanic said he could get her a new computer for $400, or she could find one in a Junkyard for $50-$75. I go to junkyards fairly regularly and I need to know what to look for. Here are the numbers off of the computer:

KY 31711 AC610
JA64000 RL8
3813

Do all the numbers need to match, or are some more important than others?

Thanks
JYS

[Manarius]

Sounds to me like it's either a fuel system problem or a Coolant Temp Sensor problem. Our ECU's don't fry very often...so, 400 would be out of my range.

[Junkyardslug]

Thanks Manarius, I will try replacing the Coolant Temp sensor first, I did a seach on 'hard starting' and came up with CTS as the cause. Even if it is not the problem a new sensor can't hurt.

JYS

[shagnsubywagn]

Hi everyone, this is the girlfriend! The problem is a little tricky with the starting--it acts like the engine is not getting enough fuel to continue running, after firing up initially.

THEN, I have to continue to crank while trying to give it a lot of gas (but it doesn't feel like it's working), and ONLY AFTER the engine backfires once, or maybe after cranking-->backfire-->dying, then cranking-->backfire-->dying again (and maybe once or twice again), AFTER THIS PROCESS, it will fire up and go just like nothing happened. It's really strange.

So the mechanic (who lives in my town--junkyardslug doesn't), felt like it's probably the computer not relaying the correct information to all the system components. He told me he "checked the other sensors" and it's the computer. I don't know what that means...but he's generally been pretty good with the car...so far...

Does that info trigger any other possible ideas about this problem? Thanks for all the help!!

[Manarius]

I still think it's either the Coolant Temp Sensor or that somehow there isn't enough fuel getting to the car. It could also be a crank position sensor, but that seems unlikely.

Did your mechanic check the basics? Spark plugs, fuel filter, fuel pump? ECU's don't usually just up and die like that. And if they do, they just die..there's no intermittant working.

[vrg3]

Actually, I was gonna say it might be the cam or crank angle sensor too. The amplitude of the signal from those sensors varies with RPM. At higher engine speeds, the signal is stronger. So maybe you're losing the signal at lower speeds. That might explain the backfiring, if it's sparking at the wrong time or at the wrong cylinder because of the signal dropping out.

As much as you trust your mechanic, you should try troubleshooting this yourselves (with the help of other board members); in my experience even very good mechanics are often completely lost when it comes to engine management.

If it's the cam or crank sensor, most likely the computer would store a trouble code for one or the other. Check for one; information on how is in a sticky thread in one of our forums.

Also, if it's the cam or crank sensor, the ECU will stop sparking as soon as the signal disappears. You could do a very ghetto check for this by removing one spark plug wire from the coil and starting the engine. The spark will arc from the coil down to the intake manifold. It'll be harder to keep the engine running with one cylinder not firing, but maybe you'll be able to tell if the engine dies first or if the spark dies first.

If you have access to a laptop with a parallel port, I think you should try running my scantool (again, look at the sticky threads). It can tell you things like what temperature the ECU thinks the engine is at, which can help diagnose the coolant temperature sensor.

The computer junkyardslug found under the steering column is actually the transmission computer. The engine control unit ("ECU") is further inside the dash and over to the left. It'll have a number something like 22611AB760 on it. It'll definitely start with 22611, anyway.

If it comes down to replacing the ECU -- though as Manarius says it's not likely -- you can definitely use one from any 92 non-turbo model, or any 93-94 non-turbo automatic model. Part numbers to look for are 22611AA93x, 22611AB05x, and 22611AB76x. The x can be any digit.

You may be able to use one from any other 90-94 non-turbo model as well, but things might not be at 100%. Part numbers include 22611AA56x, 22611AA38x, 22611AB06x, and 22611AB77x.

So after it does start, does it run perfectly well?

[dzx]

I don't know if it was weakening the signal or what but when I removed my crank sensor two days ago, the bottom part was covered in that black oil/dirt crap pretty good.

[Legacy777]

I'd still suggest starting with the coolant temp sensor. It's only $20 or so, and could be an easy fix.

[douglas vincent]

DITTO on coolent temp sensor.