Stuck throttle?

[greenlander]

The throttle on my 1994 Ranger (manual tran, 300,000 km) seems to "stick" open after I've taken my foot off the gas and/or pressed down on the clutch.

E.G.-- Downshifting, I'll press the clutch in and the engine will rev higher and higher, causing a sharp acceleration when I put the tran back in gear.

OR

The truck will accelerate even though my foot is off the gas.

Any ideas what the problem might be? I've found that by disconnecting and reattaching the battery whenever it becomes a problem seems to get me a few weeks of normal performance. I've done all the little stuff--new fuel filter, new air filter, new PCV valve, fuel injector cleaner, new idle-air control valve.

Thanks in advance.

 

[Viva*the*Ranger]

CEL come on? Have you checked to see if it has thrown any codes? How high do your rpm's get at it's worst? Did you test your throttle position sensor and vss voltage?

 

[greenlander]

Yeah, the check engine light will come on occasionally--but not always--when this problem occurs.

The engine will rev up to 4500 rpm for 3-5 seconds before it settles down. Haven't checked the TPS yet. What would I be looking for there?

 

[Wicked_Sludge]

id start with the basics. clean and lube the throttle linkage and cable. make sure your throttle body preheater is functioning properly to prevent icing. check for vacuum leaks.

 

[Viva*the*Ranger]

With the TPS, you would be testing the voltage. I think it should be about 1.0-1.1v at idle, not 100% sure. I really don't think that is your problem though. Listen to Wickedsludge, he really knows what he's talking about.

 

[greenlander]

Thanks everyone for the tips.

Wicked Sludge's suggestions make sense. I found a small hole in the upper air intake hose ?? (the one running from the MAF to the throttle body)--could that be causing it? I've noticed that when this problem occurs the engine sounds like its sucking air. It also seems to be more of a problem when the engine is hot.

Cleaning and lubing the throttle linkages--do you mean the cable running from the accelerator to the throttle plate??

 

[Viva*the*Ranger]

I'm sure that hole in your intake hose isn't doing anything good for your rig, it could be contributing to you're problem. I would fix that. As to throttle linkage; every moving part involved in actuating your throttle. Do you have a chiltons manual to reference? If not you should get one for sure. They are handy in times like this.

 

[Wicked_Sludge]

the hole in the intake tubing probably isnt causing this symptom, but it needs to be repaired. letting unmetered air into the engine is no good for anybody involved.

i was posting at the same time as you last time, so i didnt see your second post. since the CEL is illuminating, i would start by pulling the codes and see what it says.