Throttle sticks from idle
 

Today I noticed if I let my car sit and I start it up I can't move the gas pedal unless I give it a small "oomph". Then it feels like I free'ed it from being stuck somehow. It also did this again just now and when I let off the gas and applied a little throttle while coasting on the road I felt a slight 'give' when I first give throttle...but after that point it moves freely to WOT and back.

I opened the hood and played with the throttle and I felt the same small resistance from idle position. Ideas?

I would check to see if the throttle plate is closing and binding on the throttle body around the edge of the plate. If the throttle stop screw on the throttle body is turned a little to far out it will allow the throttle plate to close totally against the inside of the throttle body and cause it to stick in the bore. The screw should be adjusted so the throttle plate is just held open enough to eliminate the sticking. The adjustment is very small and the IAC compensates for the tiny bit of additional air bypassing the throttle plate. It could also be a buildup of carbon on the edges of the plate or cable sticking. I had the sticking throttle after replacing the throttle plate on my Sonoma truck and found out about the throttle stop adjustment after buying a new cable. Hope this gives you something to check out.

Flatlander

Lucky its not happening in the other direction! I actually had that happen once. Playing around with the air filter on my old monte carlo, didn't put the wingnut back on and it somehow found its way to the linkage when I was at 1/2 throttle. scary crap...still don't understand how it did it though, the 'magic wingnut' :D

My "MAF Mod" TB did the same thing when I started playing with it. If you look on the "black arm type peice I can't think of the name to" there's the shaft that goes to the TP and the other shaft goes the a large pivot. pull off the "black arm thing" and apply some cleaning and axle grease to the pivot shaft.

Uhhh...dame that doesn't make sence bud. :wink:
Try explaining a little more.

However I'm slapping myself in the face because I think Flatlander is right. I have the throttle stop screw WAY out to make sure I get a low idle voltage, but at a certain point the voltage won't go down anymore if I keep loosening the screw....so I think its out too far. I'll try that first, thanks. :)

That makes sense. It's a balancing act between the rotation of the sensor and the screw. It may take a few adjustments to hit it right.

I have the same problem after mine sits overnight. I just tap the gas before I put the key in, kinda like my old Catalina when I set the choke on a cold morning. Ahhh...the memories.

Jay

Re: Throttle sticks from idle
 

WOW, I thought I was the only one with this problem. It feels stuck, then when I put enough force to free it, I end up pealing out. I always hate that. Mine seems worse in colder weather.

K, I was playing around with the idle screw for a good 30 minutes and found a "sweet" spot where it just barely keeps the plate open (or so it seems) because I used my delicate ( :lol: ) hands to feel for any resistance...there was none by the time I finished. Tomarrow morning's cold air will show me if my efforts were in vain or not.

I'd bet all you need to do is clean the TB. Use a tooth brush, a rag and some carb cleaner. Hold the throttle plate wide open and clean the TB bore. Particularly the perimiter where the throttle plate meets it. Also clean the back side of the throttle plate and it's perimiter. You'll likely find it is all carboned up.

I had this EXACT same issue in my 99 and the 93 that I just sold. Ranger is exactly right. Just clean your throttle body and you'll be problem free.

I removed mine from the UIMs and removed all the sensors and soaked 'em in gas for about 20 minutes and then lightly scrubbed with a soft bristle brush until all the carbon was gone. Bolted it all back together and it worked like a charm...no problems since. :wink:

I always wondered what caused that. I friend of mine said it was worn bushings (I laughed at him). But the carbon thing makes sense. Is it just me, or does this seem to be a gm thing?

I've seen this happen in Ford products too. My roommate in college and my brother each had a 98 Ranger with the 2.2 (I think that's the Ford 4-banger) and both trucks did it. Neither one took the time to clean the throttle bodies and just dealt with it, but it was very evident that it was there. I hated driving them because the trucks would really lurch forward when taking off from a dead stop.

The TB was not dirty, trust me I've cleaned it quite often lately. :wink:

It was the stop screw, I tune it a lot. But yes I could see in some cases where carbon build up would cause this issue.

The oily residue inside the intake is perfectly normal. It does not need to be cleaned out...little point in it as it will come back pretty quickly.

It is a mix of some oily residue from pullover thru the PCV system and some fuel residue from the "heavy ends" of the fuel that don't vaporize sufficiently to be pulled thru the system.

When intake manifolds had carburetors and throttle body injection on them there was a lot of raw gasoline sluicing thru the manifold so they stayed pretty clean and there was no buildup like that. With modern intakes with highly tuned runners and port fuel injection the buildup is common in all engines as there is no gasoline sluicing thru the manifold anymore to clean it out and the tuned runners tend to trap the material in the plenum as it would have to run up hill to escape thru the runners....

Along with this the EGR deposits exhaust gasses into the manifold. When the engine is shut off those gasses remain. One of the first things to cool down is the TB. Much like watching moisture condense on a cold window, the gasses that remain in the manifold condense on the backside of the cooler throttle plate. The moisture evaporates but the residue and carbon don't and build up over years.

I need to clean mine I have 150K and my pedal is sticking... how do I get to it? and what is the proper procedure?? TIA

Shane

What do you drive, year and model please.

2000 Bonneville SE