Throttle sticking very badly - MAF or TB??

[Forder]

I've had issues with the throttle sticking a little the past month or two. It would occasionally stick upon startup at around 2-2.5 grand (RPM) in Park and had to hit the pedal or restart it to get it to idle normal. I thought it was the TB butterfly valve so I sprayed a little TB cleaner (not carb cleaner) in there a few weeks ago and tried to scrub it out with a toothbrush and wipe it out. It seemed to help since it didn't stick anymore for a couple weeks (although it would only stick maybe once or twice a week before that anyways). Anyways, today I'm coming back from work and it started to stick a little coming out of the parking lot, I couldn't stop where I was so I had to just hope it unstuck while I was on the highway or something, hah. Then I hit construction work and had to slow/stop on the highway, so I put it in Neutral (to keep the truck from brake torquing) and stomp the pedal to un-stick it... very bad. Now it's stuck at 4k in Neutral and almost 2k in Drive, I had to hold the brake with the RPMs at 2k for almost a mile, I seriously thought my tranny was going to fall out, lol. I stopped right as soon as I got off at a gas station to play with it and after several attempts of playing with the throttle cable it wouldn't un-stick. So I pull off the intake hose to the TB to see if it's stuck and it's not, it's fully closed, so I start it to see if it stays closed (not a good thing to do, I know), it does and idles somewhat normally (albeit a little rough since the MAF was bypassed) around 600. So I hook up the intake again while it's still running and it instantly surges back to 4k. I pull the MAF cable and it goes back down again (rough/sputtering now though, hah). I tried to drive it for a second without the MAF hooked up and it just surges again when I put it in Drive and sounds like crap, so I hooked it back up and drove it home like it was. I was literally doing 55 MPH without touching the gas pedal. I know my tranny was hurting when I got back in town and home with all the stopping/slowing, hah. I won't have time to play with it until the weekend, but after searching for MAF posts, none of them mention high idling. But since the butterfly valve was fully closed (I saw it), how is it the TB? Any insight is greatly appreciated. Thanks in advance..

 

[fixxxer]

Throttle body could be worn and causing the throttle plate to stick. Also, have you checked for binding a throttle cable? may need to be lubed. It could also be your IAC, if it is stuck fully open, the MAF is sensing more air and therefore telling the injectors to spray more fuel.

 

[Forder]

Throttle body could be worn and causing the throttle plate to stick. Also, have you checked for binding a throttle cable? may need to be lubed. It could also be your IAC, if it is stuck fully open, the MAF is sensing more air and therefore telling the injectors to spray more fuel.

Thanks, Fixxxer. IAC might be the prob, forgot they existed, hah. I know it's not the throttle cable or TB plate because it was fully closed when I played with it at the gas station. I'll have to find the IAC and see what I can do with it. I assume that can be cleaned/fixed somehow without needing a whole new one, right?

 

[aldive]

I would look carefully at the throttle cable.

Good luck ....

 

[gsx220]

my throttle cable did it to me and one day i went to floor it and the cable snapped cost me like 120 bucks from the dealer

 

[Forder]

If my throttle cable was sticking though, wouldn't that keep the TB plate open too? It was closed when I checked it and started it with the intake hose taken off the TB. If it is the cable though.. I'm sure that things a PITA to replace.. eh?

 

[Spdrcer34]

The throttle cable can be swapped in 10 minutes.

It clips to the top of the pedal, then it clips to the firewall, and finally it clips to the throttle body. The hardest part is looking at it with your head in the floorboard, trying to unclip it from the firewall.

Ryan

 

[gsx220]

yea i did mine outside took me like 5 or 10 mins and i agree spd the hardest part was being upside down trying to unclip it

 

[Forder]

Thanks guys, turns out the IAC was to blame for this one, so thanks to Fixxxer for pointing this out to me. I took it off and when I took off the servo thing, I saw that the valve stem was not centered, it was pushed in and hung on the side so the plunger stayed in the open position. I cleaned it out good with carb/TB cleaner and reassembled it, put it back on and it idled like new again.

 

[jrhogan]

I had my throttle stick last night after stomping the gas to get into traffic at rush hour, was very very scary, luckily it fixed itself and hasnt had anymore issues yet, but the reason im replying to this thread is I wanted to know what "IAC" stands for, theres no way im going to let my wife drive this truck untill I can find out where the problem is and fix it

 

[MrShorty]

IAC=Idle Air Control valve. The gadget on the side of the upper intake. It controls air flow through a bypass around the throttle plate so the PCM can control idle speed when the throttle is closed.