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Old 11-20-2000, 06:12 AM   #1
SSLegacyGT
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Member#: 2865
Join Date: Nov 2000
Chapter/Region: NWIC
Location: CdA, ID
Vehicle:
2006 Legacy 2.5i
Wagon, 5MT, Blue

Question Engine shudder/loss of power

I just returned from a trip to Vegas (from san diego). During that trip, my 97 Legacy GT (sedan) started acting up. When accelerating, I would experience a shuddering in the engine and dramatic loss of power between 1000-1500 rpms, but then the engine would seem to accelerate somewhat normally after that (sluggish but no shuddering). Small problem at first, but it has gotten worse. Any thoughts? I don't have any mods and I havent made in changes to the vehicle since I bought it.
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Old 11-21-2000, 12:10 AM   #2
vinman
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Aspen White

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I've seen posts about knock sensors and loss of power followed by normal acceleration. Try doing s search on knock sensors.
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Old 11-20-2000, 04:54 PM   #3
SSLegacyGT
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Wagon, 5MT, Blue

Thumbs up

Yeah that sounds like what I've got from what I've read. But, I'm confused on the fix. I read like 3 or 4 different fixes, none of which seemed like they were a 100% sure problem solver. I tried reseting ECU and that didnt work. Took it down to a dealer, they wanted $70 just to look at it. So I guess I'll try some of the stuff mentioned before heading their way. Thanks for the suggestion.
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Old 11-22-2000, 12:30 AM   #4
gumball
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Hey there, if the problem is w/ the ECU (its not the knock sensor, its how the ECU over-reacts to the signal), then the ECU re-set should definitely work. I had the exact same problem, and it was between 1800 & 2500 rpms, like a giant hiccup in the engine.

What happens (and the Subaru TSB confirms this) is that the faulty ECUs (the Subaru TSB reccommended replacing the ECU, not the knock sensor) over-react to the Knock Sensor signal and retard your timing. The retarded timing gets stuck in memory. So technically, an ECU re-set should clear it out and performance, at least momentarily, should be better.

If it isn't, then I'd also look into-
Ignition wires, fuel filter, air filter, clogged PCV valve etc...

and incidentally, I DID do the electronic fix (in line resistor, I believe) which mellows-out the signal from the piezoelectric mic on the knock sensor, and it works Great!


[This message has been edited by gumball (edited November 21, 2000).]
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Old 11-23-2000, 07:34 AM   #5
SSLegacyGT
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Chapter/Region: NWIC
Location: CdA, ID
Vehicle:
2006 Legacy 2.5i
Wagon, 5MT, Blue

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Ok, thanks for the extra info, I think I will be getting thinline filter. Everythiing els you had mentioned I checked right off the bat. Thanks again...
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Old 11-25-2000, 02:06 PM   #6
SSLegacyGT
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Member#: 2865
Join Date: Nov 2000
Chapter/Region: NWIC
Location: CdA, ID
Vehicle:
2006 Legacy 2.5i
Wagon, 5MT, Blue

Angry

Ok, now the check engine light has come on. Normal with this ecu/knock sensor problem? Or would it be something else?
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Old 11-25-2000, 09:56 PM   #7
kelley nelson
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Has your car been serviced recently? Check all of your plug wire connections to make sure that none are loose or off completely. Is your gas cap on tightly?

[This message has been edited by kelley nelson (edited November 25, 2000).]
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