QuickStyle

1989 iroc-z 305 tpi with 5-speed manual shift. the throttle sticks open just a bit for it to idle 1800-2000 i can push it down with my hand and it idles fine, sticky throttle? i dont think so, when car is running it will stick open, but if i have the car off and play with the throttle, it will not stick open, it will close like normal, even if i try to make is stay open a little by slowly letting it go, it will still close like normal...strange. any advice on what this could be. i have no ecu codes i checked, and the cable to the pedal is not too tight neither is the cruise control cable. any ideas on what this could be

tpi_roc

Sticky throttle is usually intermitant enough that its hard to determin for sure that whether the car is running or not has anything to do with it sticking. Take a Q-tip and some carb cleaner (or alcohol or gas or anything......) and open the throttle blades and run it around the areas the blades rest when closed, this should take care of it. I have to clean my TB at intervals, its almost part of routine maintanance.

gtaeric

Quickstyle, I have the same exact problem with my 305tpi and 5 speed. I think the TB is dirty, but then like yours, it doesn't stick at all when the car is off. I'm gonna clean it this weekend to see what happens.

StevenK

iTrader: (1)

I've got this problem, I replaced my stock TB with a holley and it persisted, so I'm gonna be changing my throttle cable when I have time.

QuickStyle

i have cleaned the hell out of the throttle body inside and out, even sprayed some lube on the binding points, and still sticks when running, and doesnt stick when car is off, i have never seen this type of thing before. i even put a return spring on the linkage to see if it would pull it back, but does not work

Ragtop89

I had a similar problem after replacing my TPS.
I replaced my TPS sensor for ***** and giggles since the one on my car is the stock unit.
I picked one up from AutoZone - it's a Wells unit.
I installed it and proceeded to set my IDLE and WOT voltages using my laptop and Moates' software.
I was having a tough time with it.
I could set my IDLE voltage and when I went to set my WOT voltage the TB would stick when I released it.
My first thought was that the butterflies were sticking for some reason but I quickly tossed that thought aside and focused on the new TPS I just put in.
At first glance it looked like the arm on the TPS was rubbing against the TB.
I loosened the 2 TPS screws and the TB snapped closed.
Hmm.
I tightened up the TPS again and blipped the throttle quickly - the butterflies didn't close all the way again.
I shined a flashlight on the TPS and I could see a gap between the TPS arm and the TB.
Looking closer I could see that the shaft that the TPS arm pivoted on was resting against the shaft the the butterflies pivoted on.
I removed the TPS and filed down the pivot post and re-installed it.
The unit had no problems fully closing after that and I proceeded to set my IDLE and WOT voltages.

Take a look at your TPS and see if it is rubbing.

QuickStyle

checked out the tps to see if it is rubbing, and it is not. the tps is new and i set the idle voltage to .5 volts, i know the specs are
0.54 Volts to 0.075 Volts ... to me that sounds like a big difference since theres a 3.5-4 volt change from IDLE to WOT. so could this be the problem? which it best at idle 0.075 or 0.54 volts?

Formula383

iTrader: (3)

I had the same prob w/ the Holley TB that I had (Bought the TB used). I called Holley and they stated it might be the shaft but was not sure. He said I could by the shft to replace it. So instead of buying the shaft I bought a new TB. I did not want to buy the shaft because if that was not the prob then I just wasted money. Seems to be that a lot of people have had probs w/ the Holley TB.

onfire

I have an 88 tpi bird and what happened when it would stick with me is the clip on the throtle cable where it attaches to the throttle body. The clip would get stuck in the grove of the cable and not let it rest so you might need to get a new clip. Check it out this was happening with and I just aligned it up to where the opening of the clip is facing down and that way the ends doesnt interfer with the cable. Hope it works out for you

Steve89GTA

NO NEED TO REPLACE THE THROTTLE BODY!! This is common after cleaning the TB. Take the intake boot off and lube the butterfly pivot points to the left and right of the intake holes. Presto, nice crisp throttle now.

TRUST ME.

Steve

onfire

sure we dont want to spend money unwisely especialy if its just a cleaning/lube that is required. That clip sometimes does wedge up inthe cable is all. Good luck man.

QuickStyle

i have lubed the hell out of the TB inside and out, the problem isnt with something sticking, because it works fine with the engine shut off, it only sticks when the engine is running.

3.8TransAM

Have u pulled the IAC out and checked it over?

diiemble it and clean it if necesaary or just replace it and then set tps and iac count per factory and/or tech articles here...

Hasnt been mentioned in this thread yet just thought i would throw it out :-)

Later
Jeremy

Steve89GTA

Yep, a sticky IAC could do it. Remove and clean the pintle well...

QuickStyle

removed the iac didnt look to bad diry wise, but the length... seemed kinda of pushed in 7/8" ... my book only goes up to 1984 and said it should be 1.120" so i dont know if its the same measurement for and 89. i pulled one off of my 89 5.7L iroc to compare, and it was a little longer so i put that one in the car after cleaning the pintle, and the same problem... throttle closes fine when not running, and when running the throttle sticks open

RednGold86Z

iTrader: (1)

With an old worn shaft or bushing on the shaft, the engine vacuum pulls on the blades and can distort the shaft enough to stick. Mine stuck a tad after cleaning, but some lube was enough to get to stay unstuck til this day even, and it's been a couple months.

Another thing was the cruise control seemed to be causing it to stick also, so I moved the cable back a notch on the cruise control actuator/diaphragm end (has a swiss cheese cable connection for adjustment).

Also, remember to reset the TV cable after removing the TB (not a sticking point, just a reminder).

Eightyninef

I'll bring this thread back to life. Holley SUCKS. I've been messing with this TB for too long. Looks like a machining marvel, but sticks with the engine on. Engine off, perfect. Something with the vacuum is overcoming the spring. Is there a resolution ?

Wouter Stijven

I had the same problem on my 88 gta. When I released the cable from the cruise control a bit, the problem was solved. Thx for the information here. Hope you guys get it figured out as well.

ws6yeats

I was just wondering if a solution ever came of this problem. I am experiencing the same issue with my 88 iroc-z. Any help would be greatly appreciated

Tuned Performance

iTrader: (92)

Check for throttle shaft play. Overtime the shaft wears into the body.

ws6yeats

If that's the case, I haven't seen any rebuild kits out there. I'm guessing the only solution at that point is to replace the throttle body right?

Tuned Performance

iTrader: (92)

Replace with a good used unit, aftermarket or find a machine shop and see if they can install bushings.

george88gta

.