93 legacy >2.5k rpm acceleration issue

[legacywagon93]

Hey, i bought a 93 legacy wagon (awd, auto, non-turbo) from a friend of mine and am having an issue.

 

Symptoms: Under 2500 rpm the car does not want to accelerate. In neutral or park it will rev just fine if it's over 1000 rpms, under 1000 you have to stab at the gas pedal a couple times to get it over 1000. This is happening when its cold and after it warms up for the first 3-5 miles of driving, then it improves (i say improves, could be it accelerates perfectly but it's still just slow to me.) but after 10ish miles it goes back to the same issue. It's displayed the CEL intermittenly- codes i've gotten have been for TPM- swapped with 3 that were "borrowed" from junk yard, i suspect that it was displaying that code (along with idle switch/circuit) because i had attempted to adjust it to just get the car to drive so my gf could get to work until we borrowed another car- no longer displaying tpm/idle codes. O2 sensor- replaced, no improvement. Purge Solenoid- from what i've read online, this wouldn't actually be causing the acceleration problem. Also, it's not come back on in ~20 miles after clearing codes. I've also tried 3 different temp sensors (also junk yard donations) because thats what my friend had said it was. I replaced the plugs because i had new set of NGK's and wanted to see the old ones. Old ones were WHITE so car's been running lean for a while.

 

I'm about to go home to check air filter (realized i hadn't done that but was supposedly changed less than 3k miles ago), fuel filter (also supposedly changed), check for vaccuum leaks (i've already done it but i figure it doesn't hurt to double check.) and would like to know how i can check the fuel filter/pressure regulater to see if they're working properly.

 

If problem is still present after checking those things, my old hs shop teacher said i can go in next weds to use their fuel system cleaning machine. I've had a hunch the whole time that fuel has been the culprit this whole time but have exhausted all other possibilities because it's not easy getting into my old hs shop. Any other experience, advice or criticisms greatly appretiated at this time...

 

cheers,

cw:-\

[Legacy777]

Welcome to the USMB.

 

It sounds like you're on the right track in looking for the problems. Have you tried running the d-check mode, which is a more active diagnostic check on the ECU. Instructions are on my site.

 

http://www.surrealmirage.com/subaru/engine.html

 

Also, as for the fuel pressure, you will need to remove the fuel supply line and tee in a line to run to a gauge. At idle with the regulator vacuum line plugged in, pressure should be around 30 psi. With the vacuum line removed from the regulator, pressure should be around 40 psi.

 

 

Also, if you haven't run across it yet, I'd suggest checking out http://www.bbs.legacycentral.org

 

There's a lot of info on there regarding the first gen legacy.

[legacywagon93]

Thanks for the welcome and the reply.

 

I tried the d-check but I no longer have any faults so it didn't turn anything up. Fuel filter is pretty damn hard to blow through so i picked up a splicer from home depot, i'm going to just bypass the filter for a couple minutes to see if my troubles go away. If I still don't have any luck I'll go buy a pressure gauge. The regulator is on the passenger side fuel rail, right?

 

Also, just a bit more info- hills are death to this car. It struggles like crazy to get up even a slight incline. I drove it about 10 miles today then went into a store. When I came back out, CEL came on. Drove another mile and pulled over, turned off the car- no more CEL and after about 2 hours of sitting, still no CEL. One symptom I left out is that in neutral or park if you just push the gas pedal it will only rev to 1.5k rpm or so but when you let off it spikes another 500 rpms then dies back down. this make sense to anyone?

 

Has anyone else had any sort of issue like this before? Maybe there are some sort of vaccuum lines that I don't know about... this is the first subaru I've ever touched, I grew up working on old bmws so i'm a bit out of my element. any more help any of you can give me would be greatly appreciated.

Edited April 30, 2010 by legacywagon93

[Legacy777]

Yes, the fuel regulator is on the passenger side fuel rail.

 

Have you rechecked the codes since the CEL coming back on? There should be a code stored in the ECU.

 

Based on the additional symptoms......you may have have a clogged catalytic converter.

 

Other thing I'd suspect is the MAF sensor.

 

It really sounds like you're not getting enough air or fuel into the engine....and/or it's not leaving the engine fast enough. So I'd check the fuel, MAF sensor, and the cats.

 

As for testing the cats, you could try removing the center mid pipe as it has a cat in it. There's still another cat in the front header piping. That would be difficult to bypass. If you have or can find a spare piping to test, that'd probably be the easiest.

[legacywagon93]

I've already swapped the MAF, the car came with a spare because the previous owner had come across a deal on one so he figured it'd be a smart buy. Didn't make any difference.

 

As far as the cat, thats another thing i've been thinking. Theres another way to check if it's working, luckily, without having to install a test pipe. If you have a laser temp gauge you check the temp into and out of the cat. I can't remember if it's more than or less than 100 degree difference but i don't have the gauge yet. Going to check it out tomorrow because my old shop should have one. Then I'll call my smog friend to remember what the difference is supposed to be.

 

No more codes stored in the ecu unfortunately. I though about unplugging the ecu then plugging it back in but theres a bunch of stuff in the way so it has to wait until i have the time. Going to clean the fuel system tomorrow and if i remember correctly the machine has a pressure gauge attached to it so i can check the regulator at the same time.

 

Thanks for your help, legacy777. i thought i'd get a few more responses than i did, but alas, nothing ever works as you want it to.

[Legacy777]

Well keep us posted on how things turn out.