So the following things helped bring the high idle down: make sure all hoses are seated nicely in their rubber elbows, not just up against the TB... seal the TB to the intake manifold with mild gasket sealer... file the stop screw down a little bit (mine isn't adjustable?? looks stripped then covered over?)

but i can watch the TB with the intake tube off... here's what happens

start it up, warms up, idles at 900rpm... give it a little gas (snap the throttle shut nicely)
and it revs at 1200rpm, then the IAC causes it to cut fuel so goes to 500 then to 1500rpm and bounces around.. but this all stops if i push the throttle wheel that last 1% closed that it didn't seem to be going to... i mean the arm is touching the stop screw, but pushing it that last little bit solves the problem. obviously i can't do this while driving... any suggestions?

also, can a LD9 throttle body be bored to 58mm? i have a 58mm plate from an eco...

Glad to see you are considering taking my advice and boring a stock TB out. It will save you a lot of headaches. People have bored out the stock TB to bigger than 58mm, so you should be fine.

It does sound like you have a vac leak though, if I'm reading what you wrote correctly. I can't really help you out much with that, except to tell you to bore your stocker. Sorry, and good luck.






Sask GM Performance (formerly SaskJbody) president

Yor replaced the rotor correctly, right? Pull the armature off again, and reset the spring to a bit tighter, one extra revolution, and rebuild the TB. Pedal feel will be firmer, and it will then close all the way. I had the same problem. No issues in the last 6 months or so with spring tension.

I turned the spring another full revolution, very tight... kind of sucked trying to drive it smoothly in 1st/reverse, but anyway it still didn't close the arm that last 1%... I can still get out of the car, open the hood, push the wheel a tiny tiny bit, and it idles fine. I tried the IAC sensor from the quad4 (it didn't like that at all... CEL instantly) (which actually idled better at first??). As far as I can tell there are no leaks except for the plate... so I think what's happening is, the stop arm is hitting the stop screw and stopping the plate from closing the last little bit, but if I push on the wheel there's a little bit of play in the throttle arm between the stop arm/wheel so it closes.

My "adjustable" stop screw isn't adjustable, theres no place for a screwdriver head on top, its smoothed over so should I just try to grind it down, or grind down the stop arm? I also reset the spring because I hated how stiff the pedal was. I gave it a rest for the day because of work and because I'm sick of taking the damn throttle body off (done it almost 15 times now?) but I think I have all the kinks worked out except for that 1% open plate. It's seroiusly such a small amount you can only tell if you're looking up close, or in the car watching it try to idle correctly.

Is this what's going on--- too much air is coming in, causing slightly high idle, car looks at TPS and says... huh, it's closed? well then, cut the gas a little... revs drop to 500rpm and car starts to sputter, engine gives it enough gas to get back up, goes to 1200rpm due to air leak, etc etc until one of the times bogging it just stalls. Also, occasionally if I drive up to about 3000rpm (though this isn't consistent) and go to change gears, I push in the clutch, and the revs stay at 3000rpm. (Maybe that'd be useful if I was trying to keep a turbo spooling) but any ideas on that? I'm trying to get ahold of someone to have them bore my stock tb to 58mm, but I'm not going to do it if it's going to cost me $100 or more... so any ideas on the stop arm/screw?

You know what, I just realized a few things.

1) I have been using the LD9 IAC
2) I tried the 2.3 IAC that I have that points UP, and the cables couldn't reach (a search would've told me that)
3) I tried the 2.3 IAC that I have that points DOWN and the CEL came on but it idled much better.

So this was a big learning experience...

Does anyone know the part number for a 2.3 IAC that points down (they cannot be turned around) or where I can buy one? My local junkyard is a real pain to work with... didn't find any on ebay...

I'm gonna try that first before I go hacking at anything else (I also had to replace the throttle plate because I thought it was deformed and tried filing around it when it didn't fit, turns out they only go in 1 way)

I think its better to bore the stock T/B. I even tried 2 different T/B's even switching around sensors. like from 2.3 sensors to stock.. same problem. but the 89 T/B gave me a CEL.

UPDATE: PROBLEM SOLVED

The TPS that was shipped with the 2.3TB didn't work, I happened to pick up a spare on a whim last time I was at the junkyard pulling a new throttle plate, and that came in handy.

On the way to autozone to check out prices on IAC solenoids ($50-$99!) my CEL came on again, and since I hadn't played around with the IAC I decided to have the guy check it out... he said that code and the code before that I reset were both the TPS... so I put on the 2.3IAC that shipped with the TB (that should have been on all along) and the TPS from the junkyard after cleaning it (did this at a gas station under cover from rain...) and the car runs mint, just as reliable as it did before but a little less low-rpm power and a little more high-rpm power. And sounds meaner

No idle bouncing, no 3k rpm hold, and A/C only makes it go up like 100rpm like it used to 'back in the day'.

So my conclusion, biggest things to check would be:

your original throttle wheel on 2.3 arm
working 2.3 TPS
working 2.3 IAC
make sure all vacuum hoses attached (T the one you have or add another)
make sure it's sealed nicely, tighten bolts down smartly not one at a time all the way
make sure the brake booster and A/C hoses aren't slipping out of the rubber elbow.

So I guess the throttle stop screw doesn't need filing... I gotta stop filing everything I don't like. Before I realized the 2.3 throttle wheel wouldn't fit my cable I realized it would hit the intake manifold, so I filed that to make it all fit... this was a big learning experience.

I ended up taking the 2.3L Wheel and turning it 180Deg (so the bottom hole was up top) (broke my 2.4L wheel taking it off). Trimmed up the side of the 2.3L wheel (the bushing was flat against the 2.3L wheel like the 2.4's was). I used the 2.3L IAC, just manuvered the connector around, works fine, no CEL there. I've got a T in the system as well, seems to work like stock. I've got an idle issue, but not sure if its related to my cams or not, had the TB on way before the cams and worked great before then, just occured after the cams.