Throttle sticks from idle
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Joined: Mar 2003
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From: Purgatory
Originally Posted by Ranger
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'* perimiter. You'll likely find it is all carboned up.
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.
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From: Oshkosh, WI
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?
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From: Purgatory
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'* 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.
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From: Genoa, Illinois
The TB was not dirty, trust me I've cleaned it quite often lately.
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.
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.
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From: Woodstock Ill.
Originally Posted by glorkar
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?
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.
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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.
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.
Shane
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