RPM Hanging Problem
 

Starting a thread on this because I think im getting close. About 1.5 months ago my car started having the RPMs hang at whatever they were at whenever I lifted off the throttle, or put in the clutch. I did a datalog and noticed my TPS sensor was not dropping to the correct voltage when I would let off the gas, and the only way to bring the RPMS down was to blip the gas. I replaced the TPS and IAC set them properly and no dice. A few weeks went by and was thinking to myself that this probably started happening one day on the way home from work when I decided to see if my cruise control worked (I have never tried it in 4 years) I flipped the switch and nothing was happening so I forgot about it, however I forgot to put the switch back to off. I turned it off and still the RPMS hang. I figured Id pull the throttle cable from the cruise control and wouldn't you know it the car was back to normal. I worked great for about a week, but this weekend it is still doing the same thing (throttle cable still un-hooked). This time though it seems to only hang in the lower rpms 1000-1400 actual rpms (2-2500 rpms on my gauge). What could it possibly be. It seems it has something to do with the cruise control.

BTW, it ONLY does the rpm thing if the car is in MOTION, it wont hang if I sit there in the driveway reving it.

The only other thing that seems "different" is the solenoid that goes to the charcoal canister makes a loud whistle sound sometimes. That seems to happen ever since this problem started as well.


Any help???

Re: RPM Hanging Problem
 

Do you have a good, Properly setup, return spring?

I had the EXACT same issue. My return spring was too loose somehow. And anything below 1/4 throttle it wasnt pulling it back. I tightened it up, and now it works great.

Sometimes its the simple things we overlook.

Re: RPM Hanging Problem
 

I have tpi, so the return spring is only what is on the throttle body. I have considered the spring being worn and have thought of putting on an external spring just to see if it fixes it. I may give that a try. Ill keep you posted, thanks!

Re: RPM Hanging Problem
 

You can also take some carb cleaner or similar and spray the shaft on the TB to make sure there is no crud on it.

Good luck.

Re: RPM Hanging Problem
 

Fixed! The throttle blades werent shutting all the way. How did you tighteen your spring????

Im going to go out and spray some carb cleaner or something on it and see if that fixes it, if not I guess i got to get a new TB.

Re: RPM Hanging Problem
 

The spring is not serviceable. If it is binding more than likely the throttle shaft has worn into the throttlebody housing and need to be bushed or you need to invest into a new throttle body.

Re: RPM Hanging Problem
 

Yeah mine is carb.

Re: RPM Hanging Problem
 

Yeah, I figured that the shaft is probably worn, however I cant find any worn out spots on the ports.

For now, I put a light "return" spring where the TV cable used to hook too and it has been working great and the rpms have been dropping as they should. Ill probably rebuild the TB over the winter.