Surge idling
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Driver School Candidate
Joined: Feb 2017
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From: North Carolina
Surge idling
I have a 95 Lexus sc400 I just replaced the ecm, it sat 8 months, now check engine light is on and it surge idles from 1200-1800 rpms. When I pinch the vacuum behind MAF it idled down and stops surging, I cleaned idle control and egr, I cracked the fuel cap and fuel was at the cap. I've checked all vacuum lines by missing brake clean I have no leaks I have noticed. Any ideas?
Racer
Joined: Oct 2015
Posts: 1,810
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From: Colorado
By what you described I would say you have unmetered air going through the pcv system. I would one, put in a new pcv valve. just because it rattles doesn't mean it is good. One with a worn or broken spring rattles. Two I would make sure all the pcv lines are on and not cracked. Make sure the oil cap is on a sealed. Make sure the oil dipstick is in and tight.
Thread Starter
Driver School Candidate
Joined: Feb 2017
Posts: 16
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From: North Carolina
Thank you, I'll get that tonight and try again in the morning. I haven't messed with non carburetor vehicles much. I really appreciate it, I'll try it and reply with the outcome
Lexus Fanatic
Joined: Oct 2003
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From: Virginia/D.C. suburbs
On CL, only moderators or the staff can actually move posts, but you can copy and paste your original question and start a new thread in that forum.
I agree with Coleroad on the pcv system. I'd also check and see if the idle air-control valve (IAC) needs cleaning, which can be done with aerosol throttle-cleaner or engine top-cleaner.........sometimes they get a carbon buildup or fuel deposits. And, if the car had sat for eight months as you described, and the battery died, some (?) idle-fluctuaton may occur here and there as the engine's computers reset themselves...or with a brand new one.
I agree with Coleroad on the pcv system. I'd also check and see if the idle air-control valve (IAC) needs cleaning, which can be done with aerosol throttle-cleaner or engine top-cleaner.........sometimes they get a carbon buildup or fuel deposits. And, if the car had sat for eight months as you described, and the battery died, some (?) idle-fluctuaton may occur here and there as the engine's computers reset themselves...or with a brand new one.
Last edited by mmarshall; Feb 18, 2017 at 05:20 PM.
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