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Guest Message by DevFuse

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90 Legacy: unusual engine problem

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15 replies to this topic

#1 Guest_james hogan_*

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Posted 15 July 2003 - 07:58 PM

I mostly post in the older subaru forum but the family car has decided to act up and I haven't really gotten a grasp of what it's malady might be.

The car is a 1990 Legacy 2wd. L. automatic.157K miles
<img src="http://groups.msn.com/_Secure/0QAAAAPwQw*bVUXiyOjbTHBc5zD1N4Z4!QAHa5FcuKME5nIvNxEM3duQUgrIj40HLJRpfnQN0eBrHQh05RRm8lo3Hb7JKNEKJSKgoEBMAAAA/DSC01883.JPG" style="border:0;"/>
Weird symptoms.

Car will start and run like normal on initial start-up.
Idles up like it should, no gauges showing anything abnormal.
Check engine light does not illuminate.

When the car warms to operating temp, idle will drop as usual, fans will even come on if needed. All ancillary systems work.

You can drive it while it's warming up, no drop in power.

When the car gets to running temperature it breaks up very violently on throttle if moving or parked.
it will usually idle OK, small dabs of the throttle don't really get it missing (1500 to say, 2000 rpm) A sharp jab will cause it to miss and break up.
Trying to get it to rise slowly on throttle will cause it to miss too.
Cannot drive the car, Oh, you can put it in gear and it will idle against the brake but don't ask it to move. Throttle will kill it. Dies a slow jerky death if you don't let up.

If you turn the car off it will not start back up until it has cooled all the way down.

Check the codes. Nothing.
Drove the car around with the green connector connected. Nothing.
Parked in the driveway, and let it warm up until the problem arose. nothing on the ECU.

Timing belt and cam seals at 125K.

I change the oil regularly at 3000m.
Havent' done a good tune-up for quite a while(-+50K).
IVe got my wife driving the RX and I'm back to driving the 86 Hatch that I rallycross on the street again. Although this car is fun, commuting in it is getting to be a bit much.

I have a couple ideas but I don't want to prejudice someone elses guess with my own theories.( So far I've been wrong)

Any ideas on my problem with this car would be appeciated.
You can ask all the Q's you like, I'm watching the post close.
Email at jaykili@cox.net.



#2 Guest_Legacy777_*

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Posted 15 July 2003 - 08:14 PM

have you pulled the plugs to see their condition?

Last time you changed the wires?

Try running some fuel cleaner through or dry-gas.

Other thought would be coolant temp sensor, but it's not the normal behaivor. If you have a service manual of some kind, do some checking on the various sensors and see if they look normal.

#3 Guest_james hogan_*

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Posted 15 July 2003 - 09:01 PM

Thanks Josh.
Not to massage your ego, but I was hoping you would reply.

I figure no matter what the problem a good tune-up, and in that, I mean spark plugs, wires, air and fuel filter, PCV, and the like might not solve the issue at hand but would cross a few question marks of the list of probable causes.

what else am I forgetting with that tune-up?
Guess I could spring for an oxygen sensor too. Although pulling the plugs would answer that Q.

No service manual, but I do have an extra engine with a spun bearing for sensor swaps if need be. Not the best idea(old for old) but the most inexpensive.

Thanks for the reply,


#4 Guest_theotherskip_*

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Posted 15 July 2003 - 09:54 PM

have you checked fuel pressure? it somewhat sounds like a fuel delivery problem. i'm not sure if i am reading your post right, but do you say it runs fine when cold, but then you have problems once it comes up to temp?

#5 Guest_james hogan_*

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Posted 16 July 2003 - 04:55 AM

Yes, that seems to be the pattern.


#6 Guest_theotherskip_*

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Posted 16 July 2003 - 07:22 AM

i would check fuel pressure on the fuel rail. it could be that the pump is crapping out at higher volumes after being on for a little while. it definately sounds like it is getting starved somewhere. other things to check would include the usual sensors: coolant temp, o2. one of them could be sending a bad reading and throwing off the computer.

good luck

#7 Guest_Legacy777_*

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Posted 16 July 2003 - 11:01 AM

if you're going the route of checking fuel pumps and such. Also check the connector under the rear seat. They can have a tendancy to go bad.

#8 Guest_tcspeer_*

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Posted 16 July 2003 - 08:17 PM

Check your coil pact with a meter.

#9 Guest_tcspeer_*

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Posted 16 July 2003 - 09:02 PM

Sorry my post was so short I had to leave, What makes me think coil pact is you saying it will start back after cooling, this was a common problem with older car's that had the coil seperate, also my 97 Subaru had this voilent break up like you have stated, only my ck. engine light came on. I had code Checked and it was coil pact. Changed it and it fixed it.

#10 Guest_Legacy777_*

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Posted 17 July 2003 - 06:50 AM

Also, if you suspect a coil pack, at night turn off all the lights or go outside and see if you see tiny sparks around the coil pack. Spraying a fine mist of water around it may help see the sparks.

#11 gravelRX


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Posted 17 August 2003 - 10:46 AM

It wasn't the crank sensor, or the cam sensor, or the fuel system.

The igniter!

Now that took long eough. Hard to diagnose a problem when you can only work on it in 20 minutes at a go, in the dark, after work.

The good news is I finally had a reason to buy a new Legacy.
warranties are a good thing.

thanks for everyone's help.


#12 gravelRX


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Posted 01 September 2003 - 11:08 AM

Checked the crank and cam sensors, replaced the coil pack, and the igniter.

Same problem as described in the first post.

I have eliminated the fuel system from the equation because of the way the car acts. It's breaking up in the ignition somehow.

Hard to explain what it's doing. It's getting worse though. After the car warms up to op. temp. it acts like the ignition is cutting out for some cylinders. Bad miss, engine shakes violently when you attempt to give it throttle.

Will die quicker now than before. Will not idle after reaching op. temp.

A subaru mechanic guessed the ignition relay when I explained the problem. Same shop, talked to another tech and he guessed the same without hearing the first guys response.

How would it effect the car if this was bad? They both tried to explain where it is and what it looks like but I'm at a loss.

FSM picture or info anyone?

Today was a bit of a trail. I hate losing my temper at anything or anyone, especially an inanimate object, but this problem is really starting to get to me.

For Sale as is. 1200.00 is closer to what I really want to do with it.

Deep Breath. Diagnosing is the hard part. Fixing is easy.



BTW, I was just positive that it was the igniter. I even posted it as a fix for the same problem for someone else on the board. Jeez.

#13 Hocrest


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Posted 01 September 2003 - 11:18 AM

Just a shot in the dark, but...
I had a EA-82 that acted sort of like this, the Cat was clogged and as it heated up it would block completely and not allow any acceleration.
Ripped apart the cat and it ran great.

#14 Lorryb


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Posted 01 September 2003 - 11:35 AM

The ignition relay is a bit of a bitch to get at. In my 91 Legacy wagon it is attached to a plate attached to the left fender wall near behind the ECU. The harness plugs into it there. When I changed mine I just unplugged the harness and plugged in the new relay, leaving the old one still mounted. To get at it you have to remove the panel below the steering wheel. Then remove the ECU for better access. Its likely to cost you a bit of skin! On my wagon you could see the relay thru a little gap that would have been behind the coin box. Good Luck!

#15 Log1call


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Posted 01 November 2004 - 12:07 AM

if the coils were missing then the O2 code should set and the check engine light should come on. It seems likely if it has to cool right down that it is temperature related, electrical component or connector temperature that is. I would check the earths and power wires to the computer and engine as a first easy and free option.

#16 gravelRX


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Posted 01 November 2004 - 07:23 AM

Wow, A post back from the dead. Thanks for the reply. It was the ECU. Fixed and sold. Regards,


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