The Top Mitsubishi Galant VR-4 Resource

Join the best E39A 1991-1992 Mitsubishi Galant VR-4 community and document your GVR4 journey.

  • Software Upgraded - Reset Your Password to Login
    In order to log in after the forum software change, you need to reset your password. If you don't have access to the email address you used to register your account, you won't be able to reset your password. In that case, follow the instructions here to regain access to the forum.

Idle issue


Active member
Mar 30, 2013
Owensboro, KY
Hey guys newb here in need of some help. Recently bought my stock 200k #1058.
Recently Ive been having some idle serge issues it started out only when the clutch was engaged and then progressed to any time at idle. So today I did some digging figuring I'd find a vacuum leak and i did. On the "A1" port comming off the intake going to what looks like some kind of idle warm up sensor below the thermostat. Can someone tell me what this does? Long story short during the process of replacing these vacuum lines the vacuum port on the sensor broke so I capped it off until I can order a new one.

I replaced the worn out champion plugs And capped off A1 and A 2 and replaced the fuel filter. Idle problem is still there but seems a little better if I let it life long enough it will smooth out sometimes. It is possible I have another vacuum leak but is there any common issues that would cause this? There are so many vacuum lines and everything is burried, can I eliminate any of this clutter? I tried to do a search for a how to on this but came
Up empty handed.

Any help would be greatly appreciated.


Active member
Dec 26, 2012
I personally just eliminate all the soleniods and ect. But I've also never tried to have a car smogged with them all removed. I'm no emissions specialist but I believe with obd1 all they do is smog it so as long as you still have a cat you should be good. I've never had a check engine light from removing them. As far as the idle issue goes, your sucking un-metered air from somewhere. The easiest way to find where is to do a boost leak test. Most common areas on old 4g63's are the biss screw oring and throttle body shaft seals. You could also have a burnt up idle speed controller, but I'd definitely start with a boost leak test.
Support Vendors who Support the GVR-4 Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications RixRacing RockAuto RTM Racing STM Tuned

Recent Classifieds Listings