I've got an 88 Camaro with a vortec 350 with TBI. I'm having a problem with the throttle sticking open. Every time I let off the throttle the TPS stays open at around 7% or 8%. I have to mash down on the throttle and let off real quick in order to get it back to zero. It also happens when I place the car in drive or reverse from park. I push on the throttle to get the car moving and the throttle stays open. Again, I have to give the throttle a quick hit with my foot to get it back down. I know one possibility is an IAC problem. I was wondering what else it could possibly be? The return spring seems to be fine. I've visually and physically checked it and the spring is tight. I would greatly appreciate any help and info.

Thanks,

Gene

 

I had the same problem with my Cadillac's thottle body sticking and idling very high. I was going 40mph without even touching the pedal. All I did was spray some wd-40 on the IAC and also on the thottle spring return. This fixed the problem for me and I haven't had any problems with it yet. Hope this works for you.

 

If you are getting a 7% - 8% TPS with your foot off the pedal then the IAC valve is not the problem. If it NEVER goes to zero your TPS could be messed up/out of adjustment, but you say it sometimes goes back to zero and other times not. This means the throttle blades are physically getting stuck open when they should not be. It could be a number of things, your best bet is to take off the air cleaner and mess around with the throttle by hand. Try and get it to stick by hand and see what is causing the problem. Your cable might be bent or mangled somewhere, blades tweaked, throttle shaft bushings worn out, debris stuck somewhere, etc etc etc. It needs to be personally investigated, might be dangerous to drive like that.

 

Thanks for the replies. I'm going to have it checked it out. I bought a rebuilt and bored throttle body from xtremefi so I hope it's not a problem with the throttle body. Also, yes it does go back to zero after I give the throttle a quick hit and let go. I did put WD-40 on the return spring but didn't think to put any on the IAC.

Thanks,

Gene

 

Lubricate the throttle and throttle cable, and it should be fine.

 

Well, I played around with the throttle by hand and I was able to get it to stick. I've done that with carbureted cars but didn't think to do it with a fuel injected car. I had to push it closed by hand after I got it to stick several times. I lubed the spring on both sides of the TB. It still sticks even after the lube. I can't see anything wrong with the cable but I'm going to take a closer look and see if the cable is binding anywhere. Thanks for the replies.

Gene

 

I went out and lubed the springs more and I worked the throttle blades open and closed several times. This seems to have taken care of the problem. I also re-adjusted the throttle stop screw. Now, whenever I let off the gas the TPS goes back to either 0% or 1%. I drove it around for over half an hour and it didn't stick. Hopefully it stays that way. Thanks to all who chimed in.

Gene