Hey Eddy, thanks for getting back to me. I just went out there with an old timing light that I was hoping to work, no luck. I was able to hook the alligator clips back up to do the timing and the idle dropped back down to 1000rpms. I then loosened the distributor nut to turn the distributor...when i started it was in the middle range of adjustment. when i turned it one way the idle got fast, the other way it got slower...I got it down to 750rpms and tighten the nut, went for a drive but had less power. The idle after taking the alligator clips off was about 1200rpms. I'll see what I can do about getting a working timing light and report back with more info. Also, in the factory service manual group 8 "ignition systems"...it seems there are pages missing on timing. damnit. I looked under my hood to see what the timing should be and it looks like the hood might have came from a 4 cylinder...lol...what should the timing be set to?

thanks again!

Man what a mess! Sorry I didn't click on this thread last year. Long story short, there is too much air entering your engine. The question: From where? Since it seems to change, I think it's electrical and controlled by the ECM. IMO on old Mitsus it's easier to eliminate the electronic controlled idle features. Perhaps because I live in warm weather and don't need them.

I'm not familiar with CA smog laws or 1989 TB's. But if your '89 TB is anything like all of the other Mitsu TB's I've seen, I think this will work for you. Take a look at your TB and let me know if it looks like this:


If yes, I think your FIAV is the problem. Pop out the copper plug and turn the big plastic screw all the way in. Spray it with PB Blaster first and let it sit for a few minutes.


Put the copper plug back in, assemble, and adjust the BISS. If it doesn't work you can go a step further and fill it in with JB Weld. I have this done to my Galant and it has a rock solid idle all of the time.

If this doesn't work, then your IAC is crazy. Remove it and run the plastic all the way out. Re-install it and DO NOT plug in the wiring harness.

If this doesn't work, replace the o-rings on the TB shaft (although I don't think you will get this far). If this doesn't work, replace all of the ghetto gaskets and RTV with genuine OEM Mitsu gaskets.

More info:
http://www.dsmtuners.com/forums/articles-intake-exhaust/320951-fiav-adjustment-disable.

http://www.dsmtuners.com/forums/newbie-forum/177292-fiav-blockoff.html

What he said, but set the damn timing first, or all your idle adjustments go out the window...

Thanks MBrannon for jumpin in on the conversation. I dont know if you had the time to read thr whole post or not, but I replaced the whole throttle body with a used one from the junk yard and it didnt make any difference. Do you think both throttle bodies have the same problem going on? Also, how would you go about popping out that copper plug? Does it screw out or just pop out?

Hey Eddy, I went to napa to get a timing light today and they didnt have any in stock. I'll get one as soon as I can and that will be my next step before anything else.

Thanks again!

Yes I read the entire thing. Yes I think both tbs have the same problem.

Me too. Sort of. It's a common failure. What I've found is that if the isc or fidle fails, the other two idle adjustments get messed with/up instead of finding and fixing the real problem.

MB, I've never seen that adjustment before. Dave took one apart, but I don't think he ever managed to get pics posted on it. I assume it just closes up the fidle when the wax pellet fails.

When new, all of the Mitsu idle designs were great. A brand new TB with all new parts would be the best way to go. Unfortunately the cost of this would probably total most of our vehicles value, so IMO eliminating them is a great alternative. Especially for guys that live in warmer climates. With age, all of these moving parts inside the TB corrode, rot, stick, etc causing these idle issues. You can completely eliminate all of the components with a block-off plate like this:



Or you can use JB weld and keep the IAC for less $. I think this is the best option. Below are some pics.

Sorry for the big pic. Why can't I post more than 2 pictures in a post? That's messed up.

This past one shows the ports that need to be JB welded. I'm getting old! I can barely use the internet correctly anymore.