My throttle plates tend to stick open when the engine is on, and hovers around 1000 to 1500 rpm after I have given it gas to move forward and then let go of the accelerator. I can also duplicate this behaviour moving the throttle plates open a little by hand and letting go. The throttle plates do not fully close. If I tap the accelerator quickly, the plates fully close.

The strange thing is that if the car is off, the plates do not stick open. For example, I can move the throttle plates open by hand and let go, and they fully close. I have even throughly cleaned the TB and there is not gunk left.

It almost seems like the engine is sucking too much, causing the throttle plates to remain open a little, if that makes any sense... The car is also idling very rough after it has come out of cold start up mode.

Any help would be appreciated.

 

try and replace the T.P.S, sounds like its sticking

 

lube up the throttle cable, or check your idle speed?

 

Thanks for the suggestions, however, if you noticed in my post, I stated that the throttle blades don't stick open when the engine is not running. So that would tell me the TPS or the throttle cable are not sticking. If they were sticking, they would stick all the time, regardless if the engine was on or not. But, I guess now that I think about it. Maybe with the engine running, the air getting sucked in by the engine is causing the blades to stay open a bit cause they are a little sticky? And maybe when the engine is off, there is little resistance so it appears the blades are not sticking?

 

you have the right idea . engine vacuum is holding it open , i dont think you can just replace the spring

more than likely your tb is worn out inside , you'll probably have to replace it *shrug*

 

When it is sticking, check the TPS voltage to see if it really is sticking. Also remove the cables from the throttle and see if things change. You might have to take your throttle body out and give it a through clean wich includes the IAC.

 

My corvette is doing the same thing. It's likely because the shaft the throttle blades are on is either worn or at least in need of lubrication. Spray some lubricant on it and work it in and see if it fixes it. If not, it may be necessary to get another throttle body.

 

Jim just to clarify, is it only the TPIS TB that is serviceable, and the stock one isn't?

 

Stock TPS are servicable from the standpoint you take it out and replace it.

Could it also be because of dirt buildup and a weak return spring?

 

Every winter here Mine sticks and I have to reconnect the T/B coolant lines, I think it has something to do with the temperature and the different types of metals. It always works for me.....

 

Interesting you should mention the TB coolant lines. I had just taken them out about a month ago. But, it doesn't get that cold here (so. cal) and it happens even after the car has been driven for a long time and is hot. So I don't think that is the problem, but just interesting you mentioned that...

 

I agree 100% throttle shaft and or bore is wore out. Needs bushing installed or a new TB.

 

Agreed with Biggs. Worn out throttle shaft/bushings. Another poossibility is that the throttle plate screws that hold it to the shaft are loose, allowing the plates to wander around on the shaft and wedge in their bores at a funny angle.

Want to know why it only happens with the engine running? Imagine 18" of idle vacuum trying to suck the rather large throttle plates back into the engine. It applies a lot of force on them. You can imagine how this could make losse/sloppy/worn out parts "move around" in funny ways.

 

I wonder if that's causing it to have a rough idle? If the plates are wobbly, it would affect the idle, right? Seems like the rough idle and throttle sticking started happening at exactly the same time...

 

I also wonder if the play in the TB could result in a vacuum leak. I have quite a bit of play in mine, and at idle, the IAC has 0 counts. I also have high BLM's throughout, even though my inj's are too big for my engine.