Welcome to the North American Subaru Impreza Owners Club Saturday April 19, 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 > Built Motor Discussion

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 08-13-2007, 05:24 PM   #1
TurboDXsti
Scooby Specialist
 
Member#: 106671
Join Date: Feb 2006
Chapter/Region: Tri-State
Location: NJ
Vehicle:
2006 Sti
grey

Default Colder spark Plug question

I've read the Spark plug FAQ topic and clicked on a few of the links , but I'm still alittle confused . I'm having misfire/CEL on cold startup , but once I start driving the car is perfect. On cold startup , when the needle starts to fall from 1500 rpm to the 750 rpm it gets erratic inbetween and sometimes throws a misfire on all 4 cylinders , once the proper operating temp is achieved no more misfire or erratic tach issues .

My setup is

06 STI
Rotated mount setup
Blow through MAF
1 step colder plugs gapped to .028

Plugs are less than a month old


Car made 480 whp on the Dyno @ 28psi ( pump gas/100% meth)

I've been reading where some ppl switch back to the stock plugs and problem solved . Will I have to retune if i switch back to the stock plugs ?
Does Stock plugs limit limit the amount of power the car will make with a bigger turbo ?
* Registered users of the site do not see these ads.
TurboDXsti is offline   Reply With Quote
Old 08-13-2007, 06:04 PM   #2
jays05
Scooby Specialist
 
Member#: 78165
Join Date: Dec 2004
Chapter/Region: South East
Location: SC
Vehicle:
05 STI 35r + e85

Default

I have seen some tuners mention that stock heat range plugs work best. I myself just switched from one-step colder plugs back to the oem plugs that came with the car. I was having misfire issues and somehow the gap had opened up a lot on the colder plugs (my biggest feeler gauge was .035 and it was loose). Didn't have to retune anything, but my tune is far from polished. Car runs like a raped ape now
jays05 is offline   Reply With Quote
Old 08-16-2007, 02:18 PM   #3
vtec2sti
Scooby Newbie
 
Member#: 109973
Join Date: Mar 2006
Chapter/Region: South East
Location: Tampa, FL
Vehicle:
06 STi
Blue

Default

i have a similar set-up as you and the exact same issue but i had mis-fire one 1 & 3. I cleared the code and it came back. i even had the 1500-750rpm thing, followed by misfire code during cold start up but perfect operation when warm. this all started the day after 3 back to back runs at the strip.. before that, it was normal operation.

car is 06sti w/gt35r & colder plugs...

i called my tuner (Doug at Topspeed) and he told me to change the plugs. i changed them and it is about 75% better now. the issue is not nearly as bad as it was. just let it idle about 15 seconds then drive off slowly. i have not been able to get rid of the surge thing when cold but the new plugs kept the mis-fire code away, and the surge is very much less pronounced than it was.

i have one step colder than stock.

car runs great and I have been running that way for about 4 months
vtec2sti is offline   Reply With Quote
Old 08-17-2007, 06:03 PM   #4
TurboDXsti
Scooby Specialist
 
Member#: 106671
Join Date: Feb 2006
Chapter/Region: Tri-State
Location: NJ
Vehicle:
2006 Sti
grey

Default

cool thanks for your reply
TurboDXsti is offline   Reply With Quote
Old 08-17-2007, 09:28 PM   #5
vulpina
Scooby Newbie
 
Member#: 131903
Join Date: Nov 2006
Location: France
Vehicle:
GC8 PPG EJ25 GT3082
dark blue 95H

Default

so there is no point going colder plug on hybrid ?
vulpina is offline   Reply With Quote
Old 08-17-2007, 09:37 PM   #6
Acostafan
Scooby Specialist
 
Member#: 67398
Join Date: Aug 2004
Chapter/Region: South East
Location: Chattanooga, TN
Vehicle:
2002 Now with 100%
RDA of 2.5l Goodness!!!

Default

^^^Depends, but in general, no point really.
Acostafan is offline   Reply With Quote
Old 09-25-2007, 06:11 AM   #7
hotrod
Scooby Specialist
 
Member#: 14141
Join Date: Jan 2002
Location: 13.239@102.85 @ 5800 ft on 13T
Vehicle:
2002 Impreza WRX
e85forum.net

Default

Quote:
so there is no point going colder plug on hybrid ?
It depends on if you need colder plugs (each engine and tune is different). This is not a one size fits all change. If the plugs are fouling or misfiring cold you probably should go to a warmer heat range. If the plugs are running hot and your having detonation problems at high boost try a colder plug.

For performance applications, run the coldest plug you can that does not cause drivability problems. For daily drivers with moderate tunes almost without exception the stock plug is the way to go.

If you want to know if your plugs are too cold or too hot, you need to learn to read the plugs. For heat range you want to look at the discoloration band on the ground electrode. If it right near the tip the plug is too cold. If it is a couple mm back from the tip of the ground electrod your about right. If the whole ground electrode is discolored, the plug is too hot. (this is for normal plugs not sure how the newer plugs show color on their ground electrodes but it is probably the same)

Larry
hotrod is offline   Reply With Quote
Old 09-25-2007, 09:27 AM   #8
TurboDXsti
Scooby Specialist
 
Member#: 106671
Join Date: Feb 2006
Chapter/Region: Tri-State
Location: NJ
Vehicle:
2006 Sti
grey

Default

Quote:
Originally Posted by vtec2sti View Post
i have a similar set-up as you and the exact same issue but i had mis-fire one 1 & 3. I cleared the code and it came back. i even had the 1500-750rpm thing, followed by misfire code during cold start up but perfect operation when warm. this all started the day after 3 back to back runs at the strip.. before that, it was normal operation.

car is 06sti w/gt35r & colder plugs...

i called my tuner (Doug at Topspeed) and he told me to change the plugs. i changed them and it is about 75% better now. the issue is not nearly as bad as it was. just let it idle about 15 seconds then drive off slowly. i have not been able to get rid of the surge thing when cold but the new plugs kept the mis-fire code away, and the surge is very much less pronounced than it was.

i have one step colder than stock.

car runs great and I have been running that way for about 4 months

Are you still having these issues ? or did you find a solution ?

Mine still does it if I don't let the car warm up properly , between 5-10 mins .
TurboDXsti is offline   Reply With Quote
Old 09-25-2007, 04:49 PM   #9
vtec2sti
Scooby Newbie
 
Member#: 109973
Join Date: Mar 2006
Chapter/Region: South East
Location: Tampa, FL
Vehicle:
06 STi
Blue

Default

no, only because after i start it... i drive it off gently after about a 15 second warm up. I don't have problems in the 15 second warm up.. only if i let it sit a minute or two at idle when cold.

car still runs great and has perfect idle when warm so i don't consider it a problem. it's bad for the car to let it warm up at idle for more than abuut 30 seconds anyway, so i have read

yea, after about 3 minute of driving, the idle is normal
vtec2sti 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
Theoretical Colder Spark Plug Question TarmacRally Service & Maintenance 2 01-07-2006 02:28 AM
Colder spark plugs and underdrive pulley nicktckhoo Factory 2.0L Turbo Powertrain 3 02-24-2002 09:16 PM
Colder Spark Plugs (recomendations and part numbers) djerickd Factory 2.0L Turbo Powertrain 34 02-13-2002 07:40 PM
Purpose of colder Spark plug? hkwan Factory 2.0L Turbo Powertrain 26 12-06-2001 11:07 PM
suggestion on colder spark plugs? kid22 Technical Forum Archive 9 07-24-2000 07:34 PM


All times are GMT -4. The time now is 09:25 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.