Welcome to the North American Subaru Impreza Owners Club Monday November 20, 2017
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Technical > Normally Aspirated 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. 
Thread Tools Display Modes
Old 03-03-2008, 02:03 AM   #1
Scooby Specialist
Member#: 82556
Join Date: Mar 2005
Location: Parker, Colorado
1996 Legacy L wagon

Default Compression brake down a hill ----> Misfire?

I've had a cylinder 3 misfire every now and again. It happened once like 4 months ago, and while I never got the code, it had the same kind of stumbling idle a few months before that.

I went on a canyon drive with a friend and at the end (30-40 miles of driving, and mind you not even hard driving as there were other motorists/bicyclists) I was coming down a rather long hill, second gear, about 35-40mph engine braking. Out my exhaust I could hear it humming and then a quick pop and then back to humming for another 4 seconds and then again a pop. It did this about 5 times, threw a flashing CEL, at which point it idled fine and stopped popping. Usually the motor pops a bit when I rev-match downshift coming to a stop, and it was doing this with less intensity with the CEL. I got it checked out and it was a cylinder 3 misfire again.

Mods on the car are:
Dodge Neon coil pack
NGK BKR5E plugs (1 step hotter)
91 Octane
open element short ram intake
lightened crank pulley
wrx midpipe/axle back with different muffler welded on

The misfires occurred before I had done the neon coil pack and the hotter plugs. After going to hotter plugs I make sure to only fill up on premium, and often put in e85 as well. My gas mileage has been better now that I fixed a timing issue, and I thought I'd try a pure 91 octane batch of gas, and the gas mileage has dropped quite a bit this tank, and now this misfire. I've been reading on here trying to find some ideas. Alot of them talk about arcing, but my wires are nice and snug. The plugs when I pulled them are the best I've ever seen them color wise (before it looked like the engine was running lean, but these are a nice dark caramel)

Edit: plug wires are about a year old, fuel filter is less than a year old, I put seafoam in the tank every 6 months
* Registered users of the site do not see these ads.

Last edited by Plays_With_toys; 03-03-2008 at 02:09 AM.
Plays_With_toys is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 03-03-2008, 12:39 PM   #2
Scooby Newbie
Member#: 160318
Join Date: Sep 2007
Location: Scotia, NY
2006 Outback Sport


I'm not sure why something like this would happen other than timing or a bad plug. The rich caramel color is obviously from the engine running rich. Ideally there shouldn't be much on the plugs.

I can't imagine why you'd put e85 in your engine unless you've changed some of the seals in the fuel pump. It won't be a problem now, but down the road it'll end up hurting you. But even then, I doubt it has anything to do with your misfire.

What was the timing issue you were having before this?

A real giveaway of timing being the issue is if you're pressing firmly on the gas in 2nd (at 30 or 40) then you drop your foot off the gas and the car misfires.
Other than that, I'd guess it happens periodically anyway (with this particular example being a bad hiccup) and it's less noticeable at other times due to a foot on the throttle. If the issue is common, I'd say to swap back in the old parts if you've still got them, and see if it happens then. If not, you know it's a conflict with the plugs or coil you installed.

(I'm just going to assume it's not the intake, pulley, or exhaust)
06OutbackSport is offline   Reply With Quote

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
Mountain biking down a hill!! Post here! 4x4GGG Off-Topic 9 03-03-2010 05:28 PM
HOU: Shops that do Compression/Leak down test tlsole Texas Impreza Club Forum -- TXIC 13 09-03-2009 02:48 PM
Do I need to do a Compression / Leak Down Test? Knight_Fall Newbies & FAQs 4 12-16-2008 05:54 PM
Compression Leak Down Test Results - Help!! aenima4six2 Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 24 06-11-2007 01:55 AM
Compression braking with aftermarket turbo wrx77 Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 6 09-19-2003 09:06 PM

All times are GMT -4. The time now is 03:07 PM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2017 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.