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90' Legacy running rough


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9 replies to this topic

#1 cadetman

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Posted 04 March 2005 - 05:54 PM

My 90' Legacy Wagon is acted bad.

It will run rough sporatically. When it acts up it chugs and has a lack of power. This can go on for a hundred miles of so. Or less. Then it can clear up while driving............ Or I can park it, start it the next day and no problem.

I have dumped loads of injection cleaner in the fuel, Marvel Mystery Oil in the fuel. I had thought it was for sure the fuel system but now I am not sure....
Why would it come and go so unpredictably??

Where should I look to first? I'll looked for shorting plug wires when it is acting up and see or hear no shorting out.

Perplexed.................................

#2 TheBrian

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Posted 04 March 2005 - 09:13 PM

Hmm. Could it be ice in the fuel lines? Maybe throw a bottle of isopropanol in there.
Aside from that, I have only obvious advice to offer: Give it a complete tune-up if you haven't recently.

#3 cadetman

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Posted 04 March 2005 - 10:29 PM

I have thrown just about everything into the tank.

The fact that it is on and off again makes me wonder. If it needs a tune up my understanding is that it would run rough all the time. Not get better......

Puzzles the heck out of me, I don't have a bunch of money to throw parts at her either.

Thanks

#4 HobbyWrench

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Posted 05 March 2005 - 10:57 AM

I also have a '90 Legacy wagon - owned it for a year and initially was a rough runner - with a few diff't problems.

Next time it is running rough, trying pulling the plugs individually to determine if it is a specific cylinder giving you problems. If it is, you'll see no difference in poor performance (when you hit the correct one) or it may run worse (when you cause it to lose power from a 2nd cylinder). Doing this, I was initially able to see my #1 plug wire had a small tear in the rubber that sits inside the cylinder and was arcing as I removed it - a good temporary fix was to wrap electrician's tape around it. If you identify a specific cylinder and the wire appears fine, you may check the plug - do you know when they were last replaced? (Using this troubleshooting method, I also was able to isolate a bad injector on cylinder #2.)

If it doesn't seem that 1 particular cylinder is causing the rough running, then it may be a common factor affecting all of them. Do you know when the fuel filter was last changed? That is another inexpensive fix that should be done periodically anyway.

Another factor to consider - does it act up when hot, cold or when? Providing this info may assist others here in helping you.

I also believe in trying the simple (and inexpensive) ways first, due to economic necessity (I'm currently unemployed). Good luck!

#5 djclue

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Posted 05 March 2005 - 01:29 PM

check your oxygen senor out does it take a secondfor the accelorator to kick in and does it sound like its going to die all the time?

#6 cadetman

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Posted 05 March 2005 - 05:04 PM

It does not seem to matter if it is the engine is hot or cold. Most often it has "repaired" itself after sittling overnight.

I bought plugs, and fuel filter. Do you have to depressurize this?? I have not done too much with injected cars. How do you depressurize if it is needed?

#7 cadetman

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Posted 05 March 2005 - 05:09 PM

When it is running badly it idles poorly. Sounds like it's going to die then catches itself.

Down the highway if it downshifts to the tallest gear it shudders like a bad tire. If I give it a bit more gas to force a shift (from say 2800 rpm to 3000 rpm) it "smooths" out.

Then it may clear up like it spit out a booger in the injection system.

Again its the "fixing itself" thing that baffles me.......... I drove it 350 miles awhile back runnng rough the whole way (a drag!). It sat for a couple of days..... got into it and if fired up nicey and ran wonderful the 350 miles home!

#8 cadetman

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Posted 05 March 2005 - 05:10 PM

How do you check the O2 sensor??


check your oxygen senor out does it take a secondfor the accelorator to kick in and does it sound like its going to die all the time?



#9 HobbyWrench

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Posted 05 March 2005 - 10:05 PM

Do you have a shop manual? If not, get yourself a Haynes Repair Manual for the '90-'98 Legacy - they usually are about $15 at auto parts stores. There is a lot of good troubleshooting info in there for you.

Explained within the Haynes manual is the On Board Diagnostics system, telling you how to obtain the self-diagnosis trouble codes. Some the home mechanic can get - others need to be read with a special reader. Your problem is probably being documented within this system. The Haynes manual will explain all the different sensors that feed into the electronic control module (ECM) controlling the engine, and how to troubleshoot them.

A great hotlink to check out is the following posted by Legacy777 who is an administrator of this, and another bulletin board. The second link has most of a '92 Legacy Field Service Manual which I've found to be an amazing tool.

http://www.main.expe...u_manual_scans/

http://www.main.experiencetherave.com:8080/subaru_manual_scans/1992_FSM_(Engine_%26_Electrical)/

Regarding the fuel pressure - I've done as the Haynes recommended and relieved the pressure. In the '90 wagon, there is an oval plate held down by 4 screws just behind the right back seat in the back bed - lift up the carpet that far and you'll see it. Underneath it is the fuel pump - pull the electrical connector from it. Unscrew and remove the gas cap, and then start up the car - it'll run just a short time.

When I replaced the fuel filter, the hoses running to and from it were old and cracked, so I replaced those at that time (getting hose of the right length from an auto parts store).

The irregularity of the symptoms is unique. It sounds like sitting cold for awhile seems to 'fix' it. Does it ever act up after sitting for awhile/overnight and then started up when its cold?

Good luck!

#10 cadetman

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Posted 06 March 2005 - 12:20 AM

Thanks for the great info. I have a manual(Chilten) but not the Haynes. I does not give any clear cut way to pull the codes (my check engine light is on). It talks about a MIL light flashing. Whatever that is??? I have had cars in the past that you can pull codes by manipulating the ignition key (like 5 fast on/off cycles).

It acts up when warm as well. I can be driving and hour or so, stop for gas, and it will act up. I then limp down the road and it may clear up in a couple of blocks or mile, or not til' the next day. Again, when it clears it is instantanious. Like the snap of your finger.


Do you have a shop manual? If not, get yourself a Haynes Repair Manual for the '90-'98 Legacy - they usually are about $15 at auto parts stores. There is a lot of good troubleshooting info in there for you.

Explained within the Haynes manual is the On Board Diagnostics system, telling you how to obtain the self-diagnosis trouble codes. Some the home mechanic can get - others need to be read with a special reader. Your problem is probably being documented within this system. The Haynes manual will explain all the different sensors that feed into the electronic control module (ECM) controlling the engine, and how to troubleshoot them.

A great hotlink to check out is the following posted by Legacy777 who is an administrator of this, and another bulletin board. The second link has most of a '92 Legacy Field Service Manual which I've found to be an amazing tool.

http://www.main.expe...u_manual_scans/

http://www.main.experiencetherave.com:8080/subaru_manual_scans/1992_FSM_(Engine_%26_Electrical)/

Regarding the fuel pressure - I've done as the Haynes recommended and relieved the pressure. In the '90 wagon, there is an oval plate held down by 4 screws just behind the right back seat in the back bed - lift up the carpet that far and you'll see it. Underneath it is the fuel pump - pull the electrical connector from it. Unscrew and remove the gas cap, and then start up the car - it'll run just a short time.

When I replaced the fuel filter, the hoses running to and from it were old and cracked, so I replaced those at that time (getting hose of the right length from an auto parts store).

The irregularity of the symptoms is unique. It sounds like sitting cold for awhile seems to 'fix' it. Does it ever act up after sitting for awhile/overnight and then started up when its cold?

Good luck!






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