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Old 05-18-2000, 03:53 AM   #1
wolkomir
Scooby Newbie
 
Member#: 1404
Join Date: May 2000
Location: Madison, WI, USA
Vehicle:
1942 Subaru Imagine
Flat-Black

Angry Turbo power drop out

Hey all,
I have a 98 impreza 2.5 and i'm having a really interesting/ annoying problem. i'm turbo with what is basically the minnam kit, stage II of course. anyway my problem is that at about 5 grand i hit a gigantic hesitation spot, it fels like you hit a brick wall. during this dead spot the air/fuel reads good, and the boost presure stays rite where it should be. i'm puzzled, it only happens above 5 lbs of boost, and i used to get a chek engine light. i eliminated the chekengine light with a series of chek valves which bleed off the boost preasure from the map sensor line, i'm going to try and put more of these valves in inorder to stop the problem, but i'm doubtful that that will do the trick.

my other idea is that it may be the egr valve. i didn't remove it, instead i just let it rub against the intercooler. it is not dented prety bad, and every once and a while it will stick open at idle, causing the manifold presure to rise, to like 10 in/hg, instead of the usuall 20 or so. i was thinking of removing the egr, but i can't get a plate to cover the whole up from the dealer.

so my question is, 1. anyone have any ideas on how to fix the hesitation, and 2. anyone removed thier egr valve on a 98?, it so how did you do it, please help out a fellow subie lover.

thanks
jon 98 impreza turbo
(my info is on the iclub members under wisconsin)
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Old 05-18-2000, 04:54 AM   #2
SteveS
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Location: South Jersey
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2007 BMW Z4 M Coupe
Interlagos Blue

Post

Another turbo'd MY98!

Hate to tell you, but I have experienced the same thing you are. Mine is not consistent though. I believe it has to do with the stock knock sensor. It's probably sensitive enough that it really starts retarding the timing just below 5K RPM. After 5K RPM the ECU ignores the knock sensor, so the timing is restored. There's the slight hesitation.

I really don't think it has anything to do with the EGR valve. I have been riding around with the EGR valve in my trunk since turbocharging my car. RalliSpec made me a plate. They probably still have the dimensions/template to make another one.

BTW, if you remove the EGR, you'll get another CE light for insufficient EGR flow.

SteveS
http://www.lagging.com
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Old 05-18-2000, 05:07 AM   #3
wolkomir
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Cool

cool, thanks, how about removing the factory knock sensor? he he he

hey nice to see your sight, i had been looking at it, is your dead spot really bad, and when you reset the compouter does it take a while to come back?

by the way want to shoot me youe email adress?
mine is jwolkomir@hotmail.com

also do you have any bleeder valves in the map sensor line?
thanks again jon
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Old 05-18-2000, 08:06 AM   #4
SteveS
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Interlagos Blue

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My email address is epher@lagging.com .

The hesitation I get is not that bad, just like I lifted off the gas and then got back on it. You're right though, I also don't see any activity on the J&S when this happens. I've been thinking about putting some washers under the stock knock sensor to help silent it a little. (BTW, there is a website out there with info about over-sensitive knock sensors on stock Subarus. Don't remember URL off-hand.)

After turbocharging, I had 3 codes from the ECU: insufficient EGR flow, high manifold pressure, insufficient cat performance. I fixed all three by removing the CE light bulb! Interesting solution regarding the bleeder valves though.

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Old 05-18-2000, 09:39 AM   #5
mjos
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It's timing being pulled back on the ECU. My OBDII monitor shows this. Either add more fuel at this RPM or pull back the timing using an ITC. Mine did this too before raising the FP with the Bell unit.

Mark
 
Old 05-18-2000, 09:49 AM   #6
ColinL
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Chapter/Region: MWSOC
Location: Wichita, KS and Whoring, OT
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'01 Erion CBR 929

Question

How 'bout HobieGary's knock sensor fix? Putting a washer underneath it to decrease sensitivity.
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Old 05-18-2000, 10:35 AM   #7
Tyrmeltr
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2013 Impreza WRX 5D
Plasma Blue Pearl

Post

This is interesting,I'm runnig a 98 2.5 ECU, and I don't have this problem...could it be my smaller, lower compression motor and an ECU for a larger, higher compression motor?

The only problem I have is running out of fuel at 12-14 psi after about 5,500rpms, forcing be to back off at WOT and apply maybe 80% throttle to redline (limiter is like 6750 right?) instead - That's an easy fix though. Just takes an moderate application of money.
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Old 05-18-2000, 10:43 AM   #8
R Diamond
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Location: Alexandria, VA
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04 STi (blue/gold)
98 2.5RS Turbo (sold)

Lightbulb

I can't help your hesitation problem, but I asked about the EGR problem before, and <A HREF="http://208.9.184.110/MembersList/ViewMemberPics.cfm?MemberID=361&PicNumber=3">Andre Van Den Berg</A> had the solution: cut and reweld the intercooler's edge.

Click the link to see a photo.

Richard -- Future member of the 98 RS Turbo club (when Minnam gets around to shipping a kit to me...)
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Old 05-18-2000, 01:21 PM   #9
Kevin Thomas
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http://home.earthlink.net/~hobiegary/hesfix.htm

The above link is the link to GARY's Electronic Fix. I forgot how to do the link setup and all. Been away for a while.
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Old 05-18-2000, 02:01 PM   #10
shiv
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Just a warning: Be very careful about re-installing the knock sensor. It's quite fragile inside. If it is overtorqued, it will break and you will assume an excessively retarded limp home mode until you install another one. Don't ask me how I know

Shiv
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