rough idle and lean after changeing plugs - Subaru Enthusiasts Car Club of the Sierras

stichris · 2009-10-17, 07:27 PM

ok well i went and bought some ngk plugs to get rid of the auto lights and before i did it car was running fine, after doing the plug change it sounds like i have really big cams and at idle my afrs are so lean they dont read on my gauge and when i let off of the gas it almost dies there is no vacume hoses unpluged i just did the plugs and didnt take anything out besids the battary any suggestions on what it could be???? (sorry for the ****ty spelling as well)

Dean · 2009-10-17, 08:55 PM

Sounds like a vacuum leak or MAF problem.

You could have knocked something loose. You must have removed the air cleaner and/or some part of the intake to get to the passenger side bank... Did the MAF get plugged back in right? What about the hoses to the boost solenoid? Maybe the hoses hanging onto the turbo inlet pipe or if stock, that hose itself might have cracked in the flex section.

Unplug or wiggle any other hoses to move the socket wrench?

Out of curiosity, did you check the gap on the new plugs before installing them?

Did you reset the ECU?

stichris · 2009-10-17, 09:03 PM

yea they were pre gaped 2 30 and i have aftermarket intake..so no need 2 move it and a mbc all i can think of is the gap is still a lil big or i didnt tighten them good enough and would that couse the lean reading?

Dean · 2009-10-18, 08:11 AM

Gap should not effect A/F significantly unless the gap is too large causing misfire and/or preventing combustion which would lead to a rich A/F. That could well be out of range for your gauge on the rich side, but it would run like hell...

sperry · 2009-10-18, 11:31 AM

If it sounds like the car has big cams, you're probably just not firing on one of the cylinders. You might just have one of the coilpacks loose?

stichris · 2009-10-18, 12:29 PM

i found what was wrong the purge solenoid vacume line that goes into the intake manifold was off at the solenoid and the number 4 spark plug was gaped to about 45 and the isolater was cracked

2009-10-17, 07:27 PM	#1
stichris EJ22 Real Name: chris pearson Join Date: May 2009 Location: loyalton,ca Posts: 127 Car: 2004 wrb sti	rough idle and lean after changeing plugs ok well i went and bought some ngk plugs to get rid of the auto lights and before i did it car was running fine, after doing the plug change it sounds like i have really big cams and at idle my afrs are so lean they dont read on my gauge and when i let off of the gas it almost dies there is no vacume hoses unpluged i just did the plugs and didnt take anything out besids the battary any suggestions on what it could be???? (sorry for the ****ty spelling as well)

2009-10-17, 08:55 PM	#2
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	Sounds like a vacuum leak or MAF problem. You could have knocked something loose. You must have removed the air cleaner and/or some part of the intake to get to the passenger side bank... Did the MAF get plugged back in right? What about the hoses to the boost solenoid? Maybe the hoses hanging onto the turbo inlet pipe or if stock, that hose itself might have cracked in the flex section. Unplug or wiggle any other hoses to move the socket wrench? Out of curiosity, did you check the gap on the new plugs before installing them? Did you reset the ECU? __________________ I am a Commodore PET --- Now get off my lawn you kids...

2009-10-18, 08:11 AM	#4
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	Gap should not effect A/F significantly unless the gap is too large causing misfire and/or preventing combustion which would lead to a rich A/F. That could well be out of range for your gauge on the rich side, but it would run like hell... __________________ I am a Commodore PET --- Now get off my lawn you kids...

2009-10-18, 11:31 AM	#5
sperry The Doink Real Name: Scott Join Date: Nov 2002 Location: Portland, OR Posts: 20,335 Car: '09 OBXT, '02 WRX, '96 Miata Class: PDX/TT-6 The way out is through	If it sounds like the car has big cams, you're probably just not firing on one of the cylinders. You might just have one of the coilpacks loose? __________________ Is you is, or is you ain't, my con-stit-u-ints?

2009-10-17, 09:03 PM	#3
stichris EJ22 Real Name: chris pearson Join Date: May 2009 Location: loyalton,ca Posts: 127 Car: 2004 wrb sti	yea they were pre gaped 2 30 and i have aftermarket intake..so no need 2 move it and a mbc all i can think of is the gap is still a lil big or i didnt tighten them good enough and would that couse the lean reading?

2009-10-18, 12:29 PM	#6
stichris EJ22 Real Name: chris pearson Join Date: May 2009 Location: loyalton,ca Posts: 127 Car: 2004 wrb sti	i found what was wrong the purge solenoid vacume line that goes into the intake manifold was off at the solenoid and the number 4 spark plug was gaped to about 45 and the isolater was cracked