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90 Legacy loping idle - HELP!


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12 replies to this topic

#1 Markus

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Posted 15 April 2004 - 01:49 PM

I have used this site for searches several times to help solve my Soob problems but I am stuck now and am looking for specific help from the Subaru Gurus.

A couple weeks ago the Soob (1990 Legacy LS) started idling badly. It was ok the next day then bad the day after that to the point where the whole car shakes. It runs progressively better at 1000 through 2500 plus RPMs. I have checked the TPS for resistance and idle switch location and performace (checked OK, idle switch was slightly out and adjusted), replaced the plugs, wires, cleaned the IACand reset the ECU using Legacy777's procedure. After the reset - no real change. I have spark at the coil pack for each cylinder and spark at the plugs. What I just discovered after reseting the ECU this morning is that when I remove the wires for cylinders 2 & 3 (at the same time or separately) there is no change in engine performance, I missed that last weekend. So...I'm idling on 2 cylinders and running on 4, cause the soob runs pretty good at 55mph? It seems to run ok at faster rpms.

When this started it sure seemed like a sensor shorting on a damp day and then clearing up as I stated.

Anyone have any ideas?

How are cylinders 2 & 3 related? I can't seem to find any help in Haynes.

Also, the 1990 Legacy does not have an EGR? I can't find it where Haynes shows it or anywhere else on the engine, I'd suspect that if I could find it.

Any help would be great as it is getting annoying bouncing around at stop lights.

Markus



#2 ejlain

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Posted 15 April 2004 - 04:04 PM

Possibly fuel filter?

#3 Markus

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Posted 15 April 2004 - 04:28 PM

Update,

After posting my original message I ran to the parts store and installed a fuel filter. It seemed logical to me as the cylinders that seemed to have an issue were a short hop from the working cylinder so maybe the filter was somewhat plugged and was starving the problem cylinder. (thanks for the input ejlain, I agree) $24 later no change! IT needed replaced anyway.

I pulled the codes and have a 22, detonation sensor (thanks 777). Pulled it and brass brushed the corrosion off. Cleared the codes and took for a drive. ARRGGG! It ran worse that before...missing etc. Hmmm....sensor must be working and ECU is used to non-working sensor that retards timing but hasn't lately. Reset ECU again.....which it is doing right now.

Will get back with results. Hope it drives cause I have to take a daughter to school program.

Markus

#4 ejlain

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Posted 15 April 2004 - 04:58 PM

Hmm, how about sparkplug wires? Did you look at them closely for any breaks/cracks? All plugs seated firmly?

- Ed

#5 Legacy777

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Posted 15 April 2004 - 05:42 PM

when you say cylinders 2 & 3.....which ones are you referring to?

#6 Markus

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Posted 15 April 2004 - 07:32 PM

ejlain - purchased new plug wires.

legacy777 - cylinders 2 & 3 per the Haynes manual and also there are little silver stickers on the injector wire harnesses. 2 would be driver side front and 3 would be passenger back. It seems I may have been tricked as now pulling 3 will make a performance difference BUT #2 plug wire pulled will not do a thing. Pulling wires 1 or 4 will instantly kill the engine.

At my second reset I kinda of cheated and did it without the engine being cold - actually was warm - not hot - to the touch and I also forgot not to touch the pedal before turning off the engine. Maybe that screwed up the reset BUT the code 22 is still there and it runs real bad at all speeds now. While going 55+ it surges and sputters and yuck and still lopes at idle. i
drove about 15 miles with no improvement.

I used a screwdriver to listen to each injector and they all sounded the same. I guess I will have to crank the engine and make sure that fuel is in there.

Being married with 4 daughters I tend to not spend the time I should with the soobie and let the code 22 go on to long BUT each spark plug I pulled looked fine - just worn, no evidence of dentonation.

I'm going to have to think. Any thoughts would be great.

Markus

#7 sho

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Posted 15 April 2004 - 11:35 PM

the car i'm workin on did the samething but on the passenger side pistons. still haven't found the problem.the car died and i still can't get it to start. good luck, i'll be watching your thread. feel free to look what i've done:
http://www.ultimates...ead.php?t=14559

#8 tcspeer

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Posted 15 April 2004 - 11:50 PM

Maybe the idle air control valve ( if the 1990 model has one) my 97 2.2 does the same idles rough at stop lights. The I.A.C. valve is expensive so I have not Chg. mine however I did spray some carbarator cleaner in the big hose that goes to it and it seemed to help some. I dont know if spraying cleaner in that hose is the right thing to do so you might want to see what other people think, however it did not harm mine.

#9 Legacy777

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Posted 16 April 2004 - 08:22 AM

Replace the knock sensor......it's not very expensive, and the older ones on these legacies tend to crack and short out.....which gives you the code 22.

My legacy has been doing the weird idle lately too.....I need to try and pull the IAC valve off and clean it up, to see if that helps.

#10 Markus

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Posted 23 April 2004 - 09:54 PM

Update:

I have replaced the Knock sensor and reset the ECU on a cold engine. It runs different....and maybe a bit better but still stumbles and stutters while accelerating. It still idles a bit rough but will run smooth for maybe 15 seconds and then stumbles. Removing the cylinder plug wire on #2 will effect idle as it did NOT before...so progress?

So I have: checked TPS, cleaned IAC, replaced plugs, wires, fuel filter, knock sensor. Did screwdriver listening trick with injectors and they all sound to be firing and I can smell fuel in the cylinder when I remove the plug after cranking.

Any ideas?

#11 Markus

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Posted 23 April 2004 - 10:27 PM

Information from another thread: anyone ever deal with the fuel regulator at the end of the rail for this type of problem?

#12 Markus

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Posted 25 April 2004 - 04:58 PM

I put in STP fuel injector cleaner with a full tank. Let sit, run, let sit, run, lightly tap on fuel pressure regulator.....

Idles very smoothly about 80% of time. Maybe a coincidence, will wait and see.

#13 Markus

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Posted 23 May 2004 - 08:45 PM

From another thread of mine:

I suspected the FPR so I installed a VDO in line pressure gage. At idle the the pressure is 30 psi. With the vacuum hose off the FPR the pressure is 38 psi. Both are in spec. So...I don't have low pressure. The Haynes book says "if you pressure is too low....do the pinch off test." I do this, even though my pressure is ok at idle, and my pressure jumps immediately to 70 psi for the short time I have it pinched.

I need help interpreting the Haynes Manual. Does this 70 psi pinch off pressure mean the FPR is bad no matter what the idle pressure is OR should I just not have done this test because my idle pressure is ok?

Also, Re-checking the coil pack and timing. The timing still seems to be on when it idles decently at all. But..I did notice that the strobe of the timing light stutters much like the engine. It does not have a perfectly uniform blink rate over a 5 second period. This seems to be on all cylinders (if using it an anything other than #1 is valid). The spark from the coil pack for each wire is an orange color. Is this ok or should it be blue?

One more thing to this novel: I hear definite backfires in the exhaust and sometimes through the throttle body but it seems that the timing is OK.

HELP!




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