Welcome to the North American Subaru Impreza Owners Club Thursday July 24, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated with bolt-on Forced Induction Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 03-24-2004, 12:06 PM   #1
Joncas
Scooby Specialist
 
Member#: 5349
Join Date: Mar 2001
Location: Central New York
Default Diagnose my lumpy erratic idle problem

Problem: ('99 RS ~100,000 miles)
Car idles as though one cylinder is not firing properly. Doesn't happen all the time - just maybe 1 in 10. Check engine light flashes. Seems like it happens more when my car is warm like when I shut it off like at a gas station and then start it back up than when its a cold start. Once the car is going it drives decently. Sometimes I get another CE light at high rpm.

Tried:
Swapping in my stock set of injectors (I needed to anyway) - no change. New plugs - seemed like it might have gotten a little better. Checked the spark plug wires for high resistance and they appear to ok (what should max resistance be?).

Details:
Supercharger was taken off (that's what I though was causing the idle problem with my bigger wrx injectors).
J&S safeguard (zero'd out)
Greddy E-manage (zero'd out maps)
Pretty much back to stock.

Thoughts:
Possibly the coil pack? (anyway to test it?)
Bad soldering job when I spliced the ECU that just showed up?
* Registered users of the site do not see these ads.
Joncas is offline   Reply With Quote
Old 03-30-2004, 10:50 AM   #2
clyde
Scooby Newbie
 
Member#: 14305
Join Date: Jan 2002
Chapter/Region: MAIC
Location: Pittsburgh
Vehicle:
1997 Impreza OBS
Blue

Default

Not sure how to fully test the coilpack, but one thing to try is to mist coilpack and wires with water at night and watch for light arcing.

Bad front O2 sensor comes to mind. Do you have any means of verifying AFR at idle? Were the plugs you took out sooty? Try cleaning the MAF (folks say to let it soak in break cleaner or electric parts cleaner).

Compression test?

Bad grounds?
clyde is offline   Reply With Quote
Old 03-30-2004, 12:09 PM   #3
insanesuby
Scooby Newbie
 
Member#: 23494
Join Date: Aug 2002
Chapter/Region: South East
Location: Charlotte, NC
Vehicle:
2013 WRX
Black

Default

Make sure the ground on the J&S is good. Had a guy with sort of the same problem. He had the ground for the J&S hooked up to the battery and he post was lose. Hooked him up with a good chassis ground and problem solved.
insanesuby is offline   Reply With Quote
Old 03-30-2004, 12:19 PM   #4
clyde
Scooby Newbie
 
Member#: 14305
Join Date: Jan 2002
Chapter/Region: MAIC
Location: Pittsburgh
Vehicle:
1997 Impreza OBS
Blue

Default

Also, if you've been running a lot of rich miles with the supercharger, consider cleaning your intake valves and combustion chamber. I notice a decidedly smoother idle (among other things) after running a 1/4 can of Seafoam Deep Creep through the engine (spray into throttle body with engine ~3-4kRPM), followed by 10-20oz of water (dribble into throttle body with engine ~3-4kRPM). This will work best when the engine is very hot, and if you go out afterward and heat it up again with an "italian tune". I find the water makes the biggest difference.
clyde is offline   Reply With Quote
Old 03-30-2004, 05:20 PM   #5
Joncas
Scooby Specialist
 
Member#: 5349
Join Date: Mar 2001
Location: Central New York
Default

I just did the Seafoam thing last night - funny you should mention it. My friend says alot of people on his club use it. I'm skeptical but I gave it a shot. We'll see what happens. Next I'll check the grounds. Thanks for the ideas
Joncas is offline   Reply With Quote
Old 03-30-2004, 09:27 PM   #6
Unsung Boxer
Scooby Specialist
 
Member#: 37196
Join Date: May 2003
Location: WA state
Default

with OBD2 cars, it is most proper to pull the CEL code. Sometimes it will almost answer the question for you. You can't just start guessing simply because it could be ECU caused because some other sensor input is bad.

If the CEL was out, you could start mechanical diagnosis, but at this point its worth it.

DO not just go doing these remedies that people suggest, i.e. throwing on ground straps, using sea foam, etc. While they all might solve "a" problem, it is only a 1/1000 chance that this is YOUR problem.

go to autozone or pepboys, pork out the 15 bucks to scan the code, and get back to us.

-Jake
Unsung Boxer is offline   Reply With Quote
Old 03-30-2004, 09:55 PM   #7
clyde
Scooby Newbie
 
Member#: 14305
Join Date: Jan 2002
Chapter/Region: MAIC
Location: Pittsburgh
Vehicle:
1997 Impreza OBS
Blue

Thumbs up

Quote:
Originally posted by Unsung Boxer
with OBD2 cars, it is most proper to pull the CEL code.
Unsung Boxer is right. I completely overlooked the mention of a CEL. Getting it pulled should be at the top of your list.
clyde is offline   Reply With Quote
Old 03-31-2004, 10:27 AM   #8
Joncas
Scooby Specialist
 
Member#: 5349
Join Date: Mar 2001
Location: Central New York
Default

No CE light - except when it flashes which is supposed to mean misfire.
Joncas is offline   Reply With Quote
Old 04-01-2004, 01:25 AM   #9
Unsung Boxer
Scooby Specialist
 
Member#: 37196
Join Date: May 2003
Location: WA state
Default

not true... the flashing i thought was caused by an aftermarket ECU like UTEC, which uses the CEL light as a misfire indicator....

is the CEL normall present?
-Jake
Unsung Boxer is offline   Reply With Quote
Old 04-01-2004, 01:30 AM   #10
lotusTT
Scooby Specialist
 
Member#: 23359
Join Date: Aug 2002
Chapter/Region: NESIC
Location: San Francisco
Vehicle:
2002 BMW M Coupe
Steel Gray

Default

Yes, a flashing CEL means misfire. It should stay on after its done flashing though.

The UTEC turns the CEL into a knock detection light, but that's a completely different beast, and is not normal CEL operation or similar to any other engine management device.
lotusTT is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
im still trying to nail down my erratic idle jacky599r Factory 2.5L Turbo Powertrain 87 07-30-2009 11:22 AM
* Calling All Specialists & Gurus: Help Me Diagnose My Strange STi Engine Problem! * Red Rexx Factory 2.5L Turbo Powertrain 34 01-14-2009 02:06 PM
Help me diagnose my tranny (?) problem Bullitt 2496 Transmission (AT/MT) & Driveline 1 10-22-2007 11:11 PM
Erratic idle @..... idle. SilverBullet2.5RS Normally Aspirated Powertrain 7 06-24-2006 03:07 AM
to those aware of my lumpy idle problem jmott Texas Impreza Club Forum -- TXIC 7 07-03-2002 11:25 AM


All times are GMT -4. The time now is 09:36 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.