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.

Loss of Power

Hi all,

I'm an origional owner of a Gallant VR-4. And over the years the car has just lost the "umph" it use to have. I've done some work on it (rebuilt turbo, headgaskets, timing belt, hoses, Throddle body, exhaust manifold) and still still can't get the car to "jump" like it use to! now a mechanic is telling me it could be the air flow sensor. Any opinions?? Please be as specif as possible, I dont have the slightest clue how this car operates. Thanks!

Boost leaks from the factory rubber hoses. Have a turbo shop test you system by pressurizing and then fixing any leaks. Its neat you have owned it since new. /ubbthreads/images/graemlins/smile.gif

i see in your list you dont have tune up.... plugs wires. get the fuel injectors cleaned and flow tested if theres a facility near you. also what crank walk said. check your piping from the turbo to the throttle body. if air leaks out of there... tahts air that the car is "Seeing" with the mass air flow sensor and never making it into the engine. this results in a richer condition in the air fuels. if you really want that umph back. you can always do what most of us do. upgrade the fuel pump injectors fuel pressure regulator even the turbo. get dsmlink or something of the likes and turn the boost up to 15 psi. or jsut go balls out and build the motor and crank the boost to 25 ish. you should see quite a jump in the cars "Umph" /ubbthreads/images/graemlins/wink.gif

Hey, I think thats a good idea to check all the turbo hoses for leaks, i'll be sure to do that. I've worked very hard to keep this car in stock condition, however each passing year it becomes harder and harder (due to the lack of parts). And yes of course i've tuned the car up several times /ubbthreads/images/graemlins/smile.gif It's in wonderful condition and has been my baby since the begning! Thanks for the suggestions...any more?

How many miles on the engine?

Here are some things I would check if I had a stock car down on power.

Compression and or leak down tests.

An exhaust restriction. Bad/plugged cat or something of the like.

Massive crack in the turbine housing near the wastegate flapper.

Cam timing off a tooth...or two.

Base ignition timing set incorrectly.

Thanks for your suggestions, checking for turbo leaks sounds like a good place to start. The car has 180,000 miles. Ive done a compression check on the rings, and they still check out fine. And the cat has been replaced about 20k ago. Waist gate has also been looked at, and the car runs pretty smooth, so I dont know if the cam shaft is a problem, but i'll ask my mechanic how he feels about that. Thank you very much for the advice, please any other ideas i'm all ears!

I'm with Brandon on cracks in the exhaust manifold. The only way to see the cracks is to remove the exhaust manifold & look @ the underside.

^It's surprising what a few hairline cracks can do to an exhaust manifold. That was one of my issues easy fix too.


Turn Right Racing
Staff member
Mar 5, 2001
He did state he replaced the ex manifold. But if they just put on a stock 1g type, it could be bad again.


Well-known member
Jun 2, 2008
Near Seattle, Washington
i dont see where it says the caps or ecu has been replaced

even if it's not a problem now, it WILL be. get it done

caps?? and no the ecu hasnt been replaced...what would be the symptoms or indications the ecu is going out? thanks


Well-known member
Jul 29, 2008
Colorado Springs
Caps is a shorter term for capacitors. If they have not been replaced your car will suffer or is already. Pull the ecu out and give it a look over and see if there is obvious damage then look closely under the capacitors for any leaking. A magnifying glass would work best. There is a sticky in the newbie section I think. Let us know what the condition is if possible on the ecu!

Okay. I haven't gotten around to it yet. I looked at the ECU and it seems like its going to take a few hours just to pull it off. So hopefully soon I'll be able to get around to it. I'll keep you posted how that goes...while I'm down there should i just replace the caps anyway? Do you think their expensive?


Well-known member
Jul 31, 2010
North county San Diego
Pulling the ecu is really just a ten min job. drop the under dash panel, pass kick panel, one ground, couple bolts & three plugs later... Upper part of the ecu just slips in get the bolts you can see & it will slide right out.

I guess everyone has figured out that English is not his first language or is it? I don't see the spelling Nazi's chiming in yet lol..... /ubbthreads/images/graemlins/rofl.gif /ubbthreads/images/graemlins/rofl.gif


Well-known member
Nov 30, 2009
Tucson, AZ
The instructions for removing the ECU given earlier is correct, This is how to do the replacement if you are able to, If you cannot you should be able to give those instructions to an electronics shop and they can do it for you very cheaply.

Link Link How to replace ECU Capacitors Mitsubishi

This is where you can buy the capacitors
Link to Purchase ECU Capacitors

This is how the boost leak check is performed.
Link How to test for boost/intake leaks

Pin-hole, tiny leaks will rob performance. They are undetectible without pressurizing the intake hose system.

Print these instructions and take them to your mechanic for reference.

This website site has a ton of information already discussed in the "How to" section. Read through that section and you will find almost anything you can think of about your car. Most of the users on this site are either mechanics or home mechanics technically inclined and very knowlegeble on mitsubishi vehicles.

Also, Im sure any local member would be willing to help out with anything on your car. We all care for these cars here, and want to see other owners taking care of their cars.

Good luck, and Congratulations on being an original owner! I wish I could say the same but I was only eleven years old when these cars were sold!
Last edited:
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 Forum Posts