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Guest Message by DevFuse
 

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Stumbling, bucking ... end of my rope


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9 replies to this topic

#1 salewit

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Posted 02 October 2008 - 12:16 AM

92 Legacy.

Symptoms: Bucking at light acceleration and coasting. Hot or cold. Ok only on heavy acceleration*. Has spasm attacks during idle. Can be idling smooth as silk and then all of the sudden starts trembling, then back to smooth. CEL light flashes on during moderate acceleration then shuts off. Codes are 12, 13, 14, 15, 16, 17 and 31. Cleared memory and same exact codes came back.


AFTER this started, replaced plugs, wires, coil, ignition control unit, MAF sensor, cam sensor, TPS, PVC, fuel filter, air filter, oxygen sensor (twice), temp sender (in rear).

Tested fuel pressure, fuel pressure regulator, compression, vacuum leaks, valve timing, ignition timing (but couldn't find mark on pulley).

I can't find anything else to change or check and I'm stumped. *This week I had a new symptom. During a heavy hill climb, it acted like it was running out of gas... or the engine shut down.... pumped the gas pedal and nothing. Minutes later it recovered and went back to stumbling and bucking but at least it had power again.

The only thing I haven't looked at was the ECU, but I can't find it. My book says it's behind the glove compartment or on the floor under the glove compartment. It's not there (hey maybe that's the problem!).

Any help would be really appreciated. I'm about ready to park it next to the junker I stripped the MAF out of.

#2 screwbaru2

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Posted 02 October 2008 - 12:37 AM

I know after replacing all that you'll say WTF to this but I noticed you omitted the pcv from your replacement list. If you haven't changed it you should a clogged valve will cause these symptoms though not a CEL. Also make sure the pcv hoses are clear.

#3 Gnuman

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Posted 02 October 2008 - 12:38 AM

Sent you a PM, call me. I'm near you. I make my living repairing Subarus. With just the list of CEL codes, it almost sounds like a bad connector in the wiring harness. . .
everything listed but the cam sensor goes through one connector by the battery.

#4 salewit

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Posted 02 October 2008 - 01:01 AM

I know after replacing all that you'll say WTF to this but I noticed you omitted the pcv from your replacement list. If you haven't changed it you should a clogged valve will cause these symptoms though not a CEL. Also make sure the pcv hoses are clear.


No it's on the list only I called it a PVC instead of a PCV. I've heard it referred both ways.

Gnuman: Interesting. The battery was loose on the deck and just floating around. I recently (months after the stumbling started) got a tie down kit. I'll look at that in the morning and give you a call.

#5 Manarius

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Posted 02 October 2008 - 08:10 AM

Are you sure that the MAF you pulled out of the junk car was good as well? I'd really want to test it against a known good MAF.

#6 bheinen74

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Posted 02 October 2008 - 08:38 AM

your timing belt is off a tooth or 2. please check that. mine was...how i got my 92ss so on the cheaps

#7 salewit

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Posted 02 October 2008 - 01:16 PM

your timing belt is off a tooth or 2. please check that. mine was...how i got my 92ss so on the cheaps


Yep... on the list. It's right on. In fact this is the first thing I did as I had a belt that jumped a couple of teeth when I put this engine in a year or so ago. It worked fine and smooth for more than a year after I fixed that problem.

No I'm not sure the replacement MAF is good. Where do I get a good one to check it against without buying one for $200+?

#8 Gnuman

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Posted 02 October 2008 - 04:19 PM

Yep... on the list. It's right on. In fact this is the first thing I did as I had a belt that jumped a couple of teeth when I put this engine in a year or so ago. It worked fine and smooth for more than a year after I fixed that problem.

No I'm not sure the replacement MAF is good. Where do I get a good one to check it against without buying one for $200+?

Easy, we take the one off my good running 92 Legacy, and see if that fixes things. . .

Stumbling and bucking could be caused by the MAF, but I'm also concerned about you getting all those codes, particularly all four of the injectors at once, as well as the TPS. that really sounds like a harness problem to me. . .

Oh, and the ECU on your model year is behind the drivers kick panel (behind the dash on the drivers side) If you have an automatic, it is the leftmost one. If you have a manual, it is the only one up there. . .

Edited by Gnuman, 02 October 2008 - 04:23 PM.


#9 crockettbrat

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Posted 02 October 2008 - 04:33 PM

I had a similar problem with my ej brat. The idle switch was set wrong. Its part of the tps. Very easy to adjust. Mine was just barely off and in stop and go traffic my check engine light would come on and then I'd get the bucking and jerking thing from right off idle and it would be fine once I was going more than about 15mph. Since I adjusted the idle switch I've had no problem. Hope this helps.

I'm in the east bay too if you need help.

Daniel

http://www.main.expe...PS_testing2.jpg This page has the procedure for checking the idle switch.

Edited by crockettbrat, 02 October 2008 - 04:41 PM.


#10 salewit

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Posted 02 October 2008 - 09:45 PM

Well Gnuman you nailed it! I popped the hood and wiggled the connectors behind the battery, then went under the dash and wiggled some connectors going into the ECU, and the problem is gone! I knew something was different the second I turned the key as the CEL came on and stayed on.

Tomorrow I'll clear the codes and see if the CEL stays off. I was also thinking of unplugging some of the connectors and carefully checking for bad pins and possibly spray them with an electrical cleaner before plugging back in.

But it's running just as smooth as silk and I can't thank you enough for the advice. I just wish I had tried this before spending close to $500 on all the above stuff I didn't need.

I've been driving my manual with my foot half-way down on the clutch the past 6 months to avoid this bucking. I'll have to learn how to drive again.

Thanks again!


Easy, we take the one off my good running 92 Legacy, and see if that fixes things. . .

Stumbling and bucking could be caused by the MAF, but I'm also concerned about you getting all those codes, particularly all four of the injectors at once, as well as the TPS. that really sounds like a harness problem to me. . .

Oh, and the ECU on your model year is behind the drivers kick panel (behind the dash on the drivers side) If you have an automatic, it is the leftmost one. If you have a manual, it is the only one up there. . .






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