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90 galant gsx 1/2 cylinders no comp? FIXED

MellowVR4

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Hey all, just picked this Galant GSX a month ago for 800. Drove it to a friends house and fixing little minor stuff to it. I cant seem to figuer out this idle problem that its having. it seems like a idle surge but not quite the normal idle surge that we're all familiar with. Maybe it was a iac? i changed that with two different ones that i had laying around, nothing changed, I disconnect the iac while the car was running, nothing changed. I removed my ecu and all the caps are fine no leaking goin on anywhere, BUT im pretty sure its an aftermarket ecu or replaced because its not the brass colored case, its grey? dont know if this ecu is even meant for this year? not sure. The biss screw is all the way in but still even when the car is warmed up it still does the same thing at the same RPM which is at like 1800. When i bought the car i was aware of this idle problem before hand, when i test drove the car and came back with it the problem went away, idle was normal and steady. seems to be intermitent but im not sure what could be causing this. I was thinking maybe a TPS,MAF, or TB. Anyone have any ideas on what it could be? Here are some pics of the ride.






 
Last edited:

James

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Probably FIAV. Like almost every other idle problem
 

MellowVR4

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i thought of that too, but the idle doesnt come down from like 1k to 1500krpm its more like 100 rpms increment, but a possibility tho.
 

MellowVR4

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that is my next thing to do on this car, any other issues that can cause this type of behavior?
 

James

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FIAV
ISC
Air leaks
ECU
 

MellowVR4

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Most likely its the fiav, ill do that in the next day or so.
 

5OF2k

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colorado springs, colorado
Im betting a vacuum leak, personally. Time to break out the spray and go nuts!
 

MellowVR4

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when i do the FIAV ill check for vaccuum leaks, i was gona remove the FIAV anyways.
 

James

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My wonky idle was a little bit of everything. Even as far as a shitty injector
 

MellowVR4

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Yeah sometimes it is a little bit of everything, you wont know till you go threw everything lol /ubbthreads/images/graemlins/banghead.gif
 

James

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heres what i got to deal when when i got my galant. starting from ym first BLT/fix. everything listed was bad

incorrect routed vac lines
Jpipe gasket
BOV gasket
leaking ebay bov
warped BOV flange
TB gasket
TB seals
Intake mani gasket
dead ISC
bad FIAV
clogged injector

after fixing all of thatthe car idles just fine /ubbthreads/images/graemlins/banghead.gif
 

MellowVR4

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Nice, it will be nice to have both my galant to idle nice.
 

Plan on spending a day checking and rechecking everything. Have you tested the iac out of 4 that I had none of them were .good
 

MellowVR4

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I havent, is it just supposed to move in and out once the key is on acc position?
 

MellowVR4

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Idle issue fixed, Now the timing is off. Im pretty sure the previous owner was trying to figure out why it was idle surging and started messing with the CAS. Its way off, ill set timing tomorrow. Is the base timing on a n/a 4g63 the same as a turbo 4g? can i raise the timing to 10 or higher? for better MPG?
 

FlyingEagle

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THE Ottawa
Same procedure.
Don't raise your timing. Keep it at physical 5' base, you will see like 10' degrees on a logger as compensation. IIRC.
 

MellowVR4

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Ok, thanks for the advice.
 

MellowVR4

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So, new problem. i was working on the gsx yesterday, fixing control arms and other lil issues it had. Drove it around the block and it was fine. So i was driving it home and all of a sudden it started loosing dramatic power. get off the freeway into a park and ride, start checking the easy things and decide to change the CAS thinking it was bad. Nothing changed after changing it, finally went and got a compression tester from my friends house and i have no compression on 1 and 2 cylinders /ubbthreads/images/graemlins/banghead.gif WTF happend lol. other two cylinders were 155 psi. i didnt here anything when it started happening. My thoughts are that its some valves and hopefully not a piston.
 

James

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But why would the valves get screwed out of nowhere?
 

MellowVR4

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i know, maybe burned the piston but not sure. hope not, ill take the head off this weekend.
 
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