On my 88 Mj 4.0L - I am having a weird issue with the throttle body.
When running, if i open it by hand under the hood and let it go, the
valve just snaps back to normal idle position (about 500rpm-ish.) But
when i depress the accelerator pedal from inside the cab, the throttle
will not return to idle - it stays a few mms from bottom and causes
the motor to idle as high as 4000rpms. I cannot get it to do it from
under the hood, and i cannot get it to NOT do it from the seat.
Ive replaced both the TPS and Accelerator Cable, saturated the
X-Over in WD40, and Gunked the inside of the TB to a mirror
finish... no changes, even small ones.
My only guess is that either the valve is jammed up internally on the
hinges, or that the spring that pulls the valve shut just isnt up to the
task anymore. My question: Where should I go from here?