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Old 11-23-2001, 02:00 AM   #26
ajday
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Member#: 127
Join Date: Jul 1999
Location: Seattle, USA
Vehicle:
1999 Imp RS
Rally Blue

Smile Flat spot question

I don't really have anything to add - my car's been running MUCH better since I removed the silencer. I was extremely impressed about how you replaced the silencer to check on your changes theory, though. I thought it was a horrible job taking it off - putting it back on, yi!?! A Plugs could help - if your's are getting old.
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Old 11-24-2001, 12:14 PM   #27
Fmdeadrick
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Member#: 200
Join Date: Aug 1999
Location: San Diego, CA, USA
Vehicle:
1999 Impreza 2.5RS
Black

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Preliminary results: I unbolted the knock sensor and added a rubber gasket between it and the engine block. I went for a quick test drive, and nothing changed, the hesitation was still as bad as before. Assuming that the computer had learned of the "knock" at this band, I pulled the battery and reset the computer. After an idle warm-up, I went for another test drive, and the hesitation was gone. Unfortunately, this happens every time I reset the ECU, so it will be a few days before I know if this is a viable permanent fix. I'll keep you posted.


Mark
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Old 11-24-2001, 11:08 PM   #28
Aaron'z 2.5RS
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Chapter/Region: MWSOC
Location: Hickigan
Vehicle:
'00 RS/WRX Stg5
'98 RS Stock

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Mark,

Note: After the mod is done, unless you used some loc-tite on the bolt. Try and remember to tighten the bolt every-so-often.

If you EVER get a CE light, make sure you check the tightness of the bolt before you do anything elts.

you may get an intermitent CE light after doing this(i have in the past)
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Old 11-25-2001, 02:46 AM   #29
Fmdeadrick
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Join Date: Aug 1999
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1999 Impreza 2.5RS
Black

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Aaron,

Good call, I'll keep an eye on it. Thanks.


Mark
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Old 11-25-2001, 09:49 AM   #30
fab9joe
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Join Date: Nov 2001
Location: tucson,arizona
Vehicle:
1999 2.5rs
silverthorn metalic

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after un plugging the knock sensor and plugging it back a few times iwas almost certain that was the issue. iwas planning on resetting the ecu and taking it to the dealer with this new info but thusday night on my way home from a party the hesitation dissappeared! it has been gone since!
be careful with that rubber basket if it fails my mechanic friend says it could cause major damage - an air leak.
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Old 11-25-2001, 11:38 AM   #31
Richard L.
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Join Date: Jul 2001
Chapter/Region: NWIC
Location: Puget Sound, WA
Vehicle:
'00 2.5RS Coupe, AW
'93 GMC Typhoon AWD

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fab9joe, why not try a MY00 knock sensor? HndaTch627 did some testing on his knock sensor and said he got very little activity from it. I think Subaru tamed down MY00-01 knock sensors. You can check out this thread for more info. If you decide to try a MY00 knock sensor, the part # for it is 22060AA070.

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Old 11-25-2001, 03:24 PM   #32
ColinL
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Chapter/Region: MWSOC
Location: Wichita, KS and Whoring, OT
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'03 Evo, Rice White
'01 Erion CBR 929

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thanks for the tip, but the MY00 knock sensor is $53 from subaruparts.com and insulating the MY99 sensor is, um well free.

it sounds like my hesistation takes a lot longer to manifest after an ecu reset than everyone else's. everyone: has the problem gotten worse? when did you first notice it? mine was happy for ~35,000 miles before it ever happened.
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Old 11-26-2001, 04:25 PM   #33
RigdenZW
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Join Date: Feb 2001
Location: Austin, TX
Vehicle:
2001 2.5 RS Sedan
Silverthorne Metallic

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Mine came from the dealership with the hesitation. Took it back a couple of times and they said they couldn't reproduce it.

ME: Explained I had read online about perhaps the knock sensor being too sensitive or faulty and retarding the timing and causing the hesitation since it was a common problem with 2.5 RS's in the 3500 - 4000 rpm range.

Service Tech: *blank look*

ME: Nevermind. Thanks anyways.:monkey:
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Old 11-26-2001, 04:52 PM   #34
EJ25
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Join Date: Oct 2001
Location: Canada... bent and broken 2000RS Rally
Default Hesitation

Funny... my 4000RPM hesitation went away when I:

1. Changed my sparkplugs back to copper from platinum.
2. Leaned out the fuel curve with my S-AFC based on what LongShot posted.

It's been great since then, other than the fact that I flipped the car after hitting a big rock at Tall Pines this weekend.
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Old 11-26-2001, 05:19 PM   #35
Richard L.
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Location: Puget Sound, WA
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'00 2.5RS Coupe, AW
'93 GMC Typhoon AWD

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So does anyone have an oversensitive knock sensor they want to get rid off? I would take hesitation over pinging anyday.

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Old 11-29-2001, 09:37 AM   #36
fab9joe
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Join Date: Nov 2001
Location: tucson,arizona
Vehicle:
1999 2.5rs
silverthorn metalic

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it seems almost any 'change'we make will get rid of the hesitation....for a while . thats the computer relearning the new parameters. i will force the dealer to put in a new knocksensor ot my next appointment. thanks all of you for your insight. iwill take the i-club over my local dealer for advice in a heartbeat.
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