So which plug should i use?

myquicksti · 04-20-2008, 02:06 PM

So i read all the faq and unabomber stuff "great write up" but still unclear.62,000 miles stg2 accesport forunt mount catless 3" turbo back and recirc aps bov. Fuel pump and short ram 20 psi runs great for what it is .Started little rough idle in the morning just for a second or two and smoothes out. Just started happening this week . Its been on these mods for aprox 20k miles or so and still holds 20 psi when into it an aprox 19 to 20 inches of vacum @ idle. So i figured maybe thrugh a set of plugs @ it. but now due Istick to the stock plug or a step colder.Dont mine spending the money and even if be comes a more freqent thing like having to replace every 10k or 12k. to sacrifice a little more so be it. i would have pm unabomber but i dont have a paypal account.

Thks for the help pics comming soon...

* Registered users of the site do not see these ads.

elusiv · 04-23-2008, 12:31 AM

Stock spec.

arch4life · 04-23-2008, 12:57 AM

i believe the common rule of thumb is for every 100 hp gain, drop a step colder.

in reality you really wont notice a large change between a step colder plug and a normal plug, all else equal at idle.

do you have any tuning? is the car running proper afr's on boost? these are things to consider as improper afr's can cause lots of issues, one of them being fouled spark plugs.

i wouldnt quickly put the blame on the spark plugs, if that is all you've considered. lots of things can cause a rough idle, perhaps you just need to clean out your Idle air control valve.

jaxscuby · 04-23-2008, 12:11 PM

stock boost ~15 psi (14.7) for stock plugs
20 psi get the colder plug.

elusiv · 04-23-2008, 08:01 PM

Quote:

Originally Posted by jaxscuby

stock boost ~15 psi (14.7) for stock plugs
20 psi get the colder plug.

What does 20psi have to do with anything?

04-20-2008, 02:06 PM	#1
myquicksti Scooby Newbie Member#: 146902 Join Date: Apr 2007 Vehicle: 04 sti silver	So which plug should i use? So i read all the faq and unabomber stuff "great write up" but still unclear.62,000 miles stg2 accesport forunt mount catless 3" turbo back and recirc aps bov. Fuel pump and short ram 20 psi runs great for what it is .Started little rough idle in the morning just for a second or two and smoothes out. Just started happening this week . Its been on these mods for aprox 20k miles or so and still holds 20 psi when into it an aprox 19 to 20 inches of vacum @ idle. So i figured maybe thrugh a set of plugs @ it. but now due Istick to the stock plug or a step colder.Dont mine spending the money and even if be comes a more freqent thing like having to replace every 10k or 12k. to sacrifice a little more so be it. i would have pm unabomber but i dont have a paypal account. Thks for the help pics comming soon... * Registered users of the site do not see these ads.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
What kind of spark plugs should I use?	WRX_MAVERICK	Newbies & FAQs	14	04-11-2010 06:42 PM
Which plugs should I use?	STIMORRIS	Service & Maintenance	4	05-28-2009 01:49 AM
What spark plugs should I use?	snowcrzy	Service & Maintenance	9	01-01-2007 10:54 PM
What plugs should I use?	wrspssshhhh	Service & Maintenance	4	10-17-2006 06:03 AM
what spark plugs should I use for over 550+whp on 2.5L	WRXINTX	Built Motor Discussion	20	08-09-2006 12:45 PM

04-23-2008, 12:31 AM	#2
elusiv * Banned * Member#: 170501 Join Date: Jan 2008 Chapter/Region: TXIC Location: Dallas, TX Vehicle: 2002 WRX PSM TXS Stage Eleventy	Stock spec.

04-23-2008, 12:57 AM	#3
arch4life Scooby Newbie Member#: 172588 Join Date: Feb 2008 Location: Lansing, Michigan Vehicle: 2005 saab 9-2x sti Black	i believe the common rule of thumb is for every 100 hp gain, drop a step colder. in reality you really wont notice a large change between a step colder plug and a normal plug, all else equal at idle. do you have any tuning? is the car running proper afr's on boost? these are things to consider as improper afr's can cause lots of issues, one of them being fouled spark plugs. i wouldnt quickly put the blame on the spark plugs, if that is all you've considered. lots of things can cause a rough idle, perhaps you just need to clean out your Idle air control valve.

04-23-2008, 12:11 PM	#4
jaxscuby n00b Moderator Moderator Member#: 10613 Join Date: Sep 2001 Chapter/Region: South East Location: F L O R I D A Vehicle: 2002 USDM WRX WRB	stock boost ~15 psi (14.7) for stock plugs 20 psi get the colder plug.