The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support JNZ Tuning
Please Support STM Tuned

Another idle issue

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

keeler

15+ Year Contributor
53
0
Jul 24, 2006
New Albany, Indiana
I've replaced my tps, iac, idle switch, ecu, biss screw, coolant temp sensor, and o ring cleaned the upper intake manifold, and throttle body. Boost leak shows good. EGR is blocked. no vac leaks i've checked, rechecked and tested the system with fog. the vac reads -20 pretty steady. car has a safc and wideband so i can tune it. however, my idle surges pretty badly when cold, once warm it calms down but is still pretty bad 800+ when cold 200+ when warm rpm surge. The car was stock when I got it, it surged then and continues to do so today after all new IC piping, exhaust, turbo, etc. Any help would be awesome
 
Wow, the only thing that you havent mentioned is your MAF. Have you changed or replaced that at all?
 
Ive seen a few times, that the wiring harness for the IAC behind the intake manifold will have damaged or broken wires on it. Sometimes, they even pull out of the harness and you'll never notice it unless you inspect it real close. Check it out. Its worth a shot.
 
Wow, is all I have to say. You have changed and done almost everything to do with idle. I'm having the same problems with my talon but I have probably done only three quarters of things you have done and I still have problems. I'm about change my ECU to see what happens. The only other thing I am going to do and I don't see you have done is to check your timing. It's just a suggestion and hopefully we can fix our problems.
 
I also trying to figure out this same problem with my 97 GST. I put another MAF on it, but the engine still comes out with the PO100 code. Can anyone give me any info on this..
 
FIAV blockoff?

This fixed all my idle issues.

Bottom of this page, it's called 1g FIAV plugging
http://www.ffwdconnection.com/flow.shtml
I just did mine with JB weld

I did this too eventually. MY FIAV was broken and I wasn't about to spend the money on a new one. They cost more than an adjustable cam gear. Just doesn't seam logicalLOL .
 
I did this too eventually. MY FIAV was broken and I wasn't about to spend the money on a new one. They cost more than an adjustable cam gear. Just doesn't seam logicalLOL .

LOL I know what you mean, I just opted for the ghetto JB weld and rerouting the coolant line. Probably cost me $6.00 and about 6 hours (mostly for the jb weld to dry).
 
As Matt said, if you did not ground the proper stuff at the proper time while adjusting the BISS, you could end up with some scary stuff. My vote is to pull your ECU and check your ISC drivers. I had the same issue, replaced almost everything, blocked FIAV, etc., but still had the surge. I pulled my ECU and sure enough, there were some drivers that had been annihilated.

So get the ECU out (like 30 seconds, it's behind the stereo, search ECU removal), and pop the cover off. It will be easy to tell if something is wrong or not; you shouldn't see anything if it's fine, but if it's bad, you'll easily see burn marks on the case, melted stuff inside, brown connections, etc.
 
I've replaced my ecu and it didn't solve it, I've adjusted m biss properly to no avail. I've blocked off my FIAV and my car ran like shit so I unblocked it. I've done a full throttle body swap and it didn't work. I've even gone to the extent of replacing my intake manifold...I am just stumped. Maybe it's time to go to a shop..
 
I've blocked off my FIAV and my car ran like shit so I unblocked it.
How did you block it then unblock it. Using jb weld or anything strong enough to be safe for the engine (not be sucked in) wold likely make it a non-reversable mod?. . .:confused:

Did you readjust your throttle plate angle after the mod. Perhaps using the idles switch (injector cut-off) to upen the plate up? If this wasn't done, it wont run as there is practically zero airflow.
 
dont 1990 dsms already have the FIAV blocked off? ive got idle surge too, and theres just a plate on the bottom of the TB and ive taken it off, and theres this shaft with a spring on it inside the bottom of the TB. Can that go bad?
 
Well, I'm not sure there's a point to the FIAV if it is blocked off. . . Do you mean 'if you disconnect it, it closes like a normally closed solenoid valve'. I havn't had my TB off in a while. 3 years OMG ! I remember deciding to block it w/ jb weld. . .
 
I blocked it off with a metal gasket and I adjusted it accordingly I even checked my AF ratio to make sure things were good but i could never get it done properly.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top