I bought this truck for work and all of a sudden it will rev real high when I press the clutch in to switch gears or when sitting at a light. I stopped at a parking lot and popped the hood and tried to pull the throttle back by hand but it will not go. There is a lil slack in the throttle cable but when the truck is off and I manually pull the throttle back it returns normaly. I was wondering if the little black electronic box oppisite where the throttle hooks to the throttle body is making it rev so high?
I really dont know alot about these newer trucks as I have drivin older trucks my whole life so probly using wrong terms but hope you guys get what Im saying... please help!!!

 

Kind of unsure of what you are trying to say, but that little black box is your TPS(throttle position sensor). What I'm unclear on when the truck is running and revving high, is the throttle control resting on the idle screw?
Do you have a check engine light on?
Have you adjusted the idle screw?(<do not="" do="" that
Do NOT touch that)
Do you have cruise control?</do>

 

Ok it dosent happen all the time but it seems to be happening more often the last few days. Its 4.2L v-6. I will be driving along and come to a stop and when I push the clutch it will jump to about half throtle.Im guessing half I dont have a tach. It only happens after I have drivin and pushed the throttle,not when first fired up. Yes my O2 sensor on the driver side close to the engine is throwing codes it is bad and am gonna replace. will that make my engine rev when its suppose to come back to idle?
No cruise control.
Havent adjusted any thing only stoped and tried to pull throtle back thinking the return spring had broken but it works fine when truck is off.

 

The brake pedal switch opens a 12 volt feed to the cruise controller when you say that helps.
Try disconnecting the cruise control cable at the throttle body and see if that stops the high idle.
If yes, you have the cause and a CC issue.
BTW, the VSS is part of the CC operation and may cause some effects at certain times.
Let us know because it's been a problem for some owners.
Seems to happen only on V6 MT Trucks.
Good luck.

 

what specific codes are you getting?
if you rev the motor higher when this happens do the rpms drop back down after?

 

I have no cruise control bluegrass...
The codes its throwing are p1131 and p0171 both are bank 1 to lean codes so its the first O2 sensor on drivers side. Its been throwing those codes since I bought the truck and only started this in the past week or so...

And no it dont come back down if I romp on it real quick like my old 70's pickups used to...

 

1: check for vacuum leaks
2: clean throttle body
3: clean IAC valve

is what i would try next

 

Ive gone through the vaccum lines and all apears well.
Obviously carb choke cleaner for throttle body and how do you clean the IAC Valve? And thank you guys for the help!!!

 

Why did you not say you had codes in the first post?
Both codes are the results of the same fault.
You likely have an air leak in the intake tract.
If it's bad enough the idle will be affected the same as the IAC would do if it opens up or you put foot on throttle.
If you see the throttle does not return to it's normal rest, the throttle plate is off it's stop and lets more air in. Of course the idle will go up.
The difference between the high idle condition and the codes is the air through the throttle body is meterd by the Mass Air meter and accounted for, the other air leak is not and causes the codes.
You have two troubles at the same time.
Find out why!
Good luck.

 

Pull it off and use carb and choke cleaner, make sure you keep the motor side up so you don't get any carb and choke cleaner in the motor.

 

The only way I know to test for intake leaks is starting fluid a very little at a time???? sound good to you guys?

 

You can use carb cleaner, it will drop the rpm's instead of raising them. A little safer than using starting fluid. Stilll tough I would suggest using sparingly, it will help locate the problem faster. I would also like to note that I have no formal training, Bluegrass and a few others that respond frequently on this forum have much more experience than I do. I just try to help out since this forum has helped me, and have some experience working as a "parts changer" for over five years
Anyway, GOOD LUCK!

 

Thank you very much...