When im in drive the car will happily idle at 750-850 rpms but when i throw it into neutral/park it pulls up to around 1500 rpms??? Is this normal or is something messed up

 

dont sweat that mine does the same thing

i love the higher idel my oil pressure and volts are much happier

 

Thats wierd....my 305 idled 550 when warm in drive, and about 100-200RPMs higher in park....1500 sounds high...

 

hey doug my 83 lg4 does the EXACT! same thing and i was wondering the same thing so hopefully someone will tell us why. it also cause the car to wanna jolt foward when put into gear coming fromt that higher rpm

 

well it made sense to me that with an auto its kind of in gear when in D so itd rev lower then when its spinning freely. Just noticed how high it was in park though seemed a little high but i think shes okay.

 

Here is a theory. When you go to park, you engage reverse and it bogs the engine down. The IAC opens up and tries to keep the idle at the set point that the ECM demands. When you go into park, the load is off and the IAC should close but doesn't and so it keeps the idle high. I would take off the TB, IAC and clean them both, readjust the IAC and then the TPS (in that order) and see what happens. I don't get that sort of thing tho.