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Stumbling-it's been asked before....


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12 replies to this topic

#1 turbosubi

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Posted 31 October 2004 - 05:03 PM

I'll get down to it.
  • 87 ea82t 61,000 miles
  • Engine cold, stumble in mid-pedal range
  • Warm engine, no stumble unless you get on it, between 3800 and 4000 range it starts to cut-out unless you back off the throttle.
  • recently replaced: cap rotor wires plugs fuel filter.
  • see thread "fuel filter replacement/Update Distributor" for history of this problem.
  • mech replaced distributor, ran fine for 3 days, now back to square 1.
  • Cannot afford these repairs, student on a tight budget.
  • Please, Please, Please help, if you can. Thanks Guys!


#2 Roundeye

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Posted 31 October 2004 - 05:20 PM

I'll get down to it.

  • 87 ea82t 61,000 miles
  • Engine cold, stumble in mid-pedal range
  • Warm engine, no stumble unless you get on it, between 3800 and 4000 range it starts to cut-out unless you back off the throttle.
  • recently replaced: cap rotor wires plugs fuel filter.
  • see thread "fuel filter replacement/Update Distributor" for history of this problem.
  • mech replaced distributor, ran fine for 3 days, now back to square 1.
  • Cannot afford these repairs, student on a tight budget.
  • Please, Please, Please help, if you can. Thanks Guys!

I had a similar problem with mine.

It would be extremely useful if you can get a vacuum/fuel pressure gage. A good one is around $15-$20. T into your fuel supply line and run the hose through the rubber knock-out plug in the firewall and connect it to your gage. Drive the car and note what pressures are seen under different conditions: (Idle, mild acceleration, heavy acceleration ((WOT)) , cruise and deceleration).

Next do the same test while plumbed into the intake vacuum system.

These readings will help pinpoint the problem.

I did this to mine and found the fuel and vacuum to be correct. This eliminated alot of troubleshooting. Mine finally turned out to be the Mass Air Flow meter.

#3 SubaSkeet

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Posted 31 October 2004 - 05:27 PM

heres some general ideas, since i have no real good way to analyze it in depth:

1. fouled plugs (shouldnt be an issue since you just replaced them)
2. clogged filter (again, shouldnt be a prob)
3. air leak in the intake manifold
4. probs with emissions control system

try checking the codes on your car via the ECU, see what it pulls up.

#4 Cougar

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Posted 31 October 2004 - 07:38 PM

Subaskeet has some good advice that I concure with. I particularly suspect a intake manifold leak on this since it somewhat clears up when warm. I had a leak in my car so bad you could hear the leak without the aid of a hose. Also, if you don't have some NGK plugs installed you might try those.

#5 turbosubi

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Posted 31 October 2004 - 07:43 PM

Thanks, you guys. I'll try out your suggestions tomorrow. Thanks to all who replied, your knowledge is appriciated! :)

#6 raverjames21

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Posted 31 October 2004 - 08:42 PM

Sounds sorta like my problem, except I am smelling burning coolant and mine does not get better when engine is warm. When it does this it sounds like the engine isnt gonna make it but then at WOT it picks up and gains power again. My turbo GL wagon was doing the same thing but I was pretty sure it was a result of a cracked head or blown head gasket. Do you smell burning coolant. My problem seems to be much worse than what you are experiencing. I have an evil touch that causes cars to break unexplainably.:(

#7 stngllhm

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Posted 31 October 2004 - 09:22 PM

I have an evil touch that causes cars to break unexplainably.:(


don't we all. i know i do<G>

#8 raverjames21

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Posted 31 October 2004 - 10:15 PM

don't we all. i know i do<G>

Mine has been with me for 3 different subaru's. I was hoping this car would be the reliable one.

#9 monstaru

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Posted 31 October 2004 - 11:27 PM

talk to baccaruda, he is our local turbo guy....if it happens ,it has probably happened to him.i am sure if he has the time he would be more than willing to help.tell him brian sent you.....

#10 baccaruda

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Posted 31 October 2004 - 11:43 PM

hi there. as much as i appreciate brian's kind words, i don't have much to add to the above advice at this point..
you said the problem went away for 3 days after the distributor was replaced and is now back?
i'd suspect your cap/rotor or a vacuum leak somewhere.
the stumble is what exactly? a decrease, or a total loss of power? and the car's electrical system is unaffected (dash lights stay on?)

check your codes first
http://www.troublecodes.net/Subaru/

check for vacuum leaks (spray carb cleaner around until engine RPMs change and investigate further.. careful spraying near the turbo as CC is flammable)

also, in case it's electrical, check your engine compartment ground wires (battery to engine and engine to frame are right next to each other, and there's a tranny to frame that attaches to the spare tire support.. i think that's it. add another one from the engine to frame and tranny to frame, use some burly gauge wire like 8 or 6 gauge) as bad grounding is an infamous cause of problems.

Hopkins is a pretty good shop. I wouldn't be surprised if he told you that it might not be worth your time and money to have him chase problems like this on an older car? I brought mine to him and that's basically what he said; he could fix it but it wouldn't be worth the money. I appreciate his objectivity.

#11 turbosubi

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Posted 01 November 2004 - 03:46 PM

Hey guys, I dropped by Hopkin's and had Brian go on a test drive with me. He tightened the throttle cable, but I was able to still replicate the Problem for him. The stumbling only happens between 3700 and 4000 rpm's, very noticeable when cold under load, less so when warm. I actually had to shift into 1st gear at about 25 mph when warm, bring rpm's to 3800 under full accelleration, then when I back off the throttle, it starts to stumble. He surmises a bad TPS or the sensor located between the air filter housing, and the intake ( black plastic piece with a rectangle connector on the side). He thinks he might be able to get both used from a friend of his. After reading all the threads about this problem from other people, no one has brought these topics up. I guess I'll have to wait and see if either of these solve the problem. P.S. I added Baccaruda and Monstaru to my buddy list on this site, since you two are local boys. Hope that's okay.

#12 raverjames21

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Posted 01 November 2004 - 04:59 PM

Hey guys, I dropped by Hopkin's and had Brian go on a test drive with me. He tightened the throttle cable, but I was able to still replicate the Problem for him. The stumbling only happens between 3700 and 4000 rpm's, very noticeable when cold under load, less so when warm. I actually had to shift into 1st gear at about 25 mph when warm, bring rpm's to 3800 under full accelleration, then when I back off the throttle, it starts to stumble. He surmises a bad TPS or the sensor located between the air filter housing, and the intake ( black plastic piece with a rectangle connector on the side). He thinks he might be able to get both used from a friend of his. After reading all the threads about this problem from other people, no one has brought these topics up. I guess I'll have to wait and see if either of these solve the problem. P.S. I added Baccaruda and Monstaru to my buddy list on this site, since you two are local boys. Hope that's okay.

Doesnt sound like something a TPS would cause. The MAF is however a good possibility. I am gonna check mine.

#13 Cougar

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Posted 01 November 2004 - 07:51 PM

I hope he tested the intake manifold gasket for a leak before throwing parts at it.




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