Does anyone know if the TPS is linked to the cruise control? My engine idle jumps around a couple hundred rpm sometimes and my cruise control doesn't hold as steady a speed as it use to. I am going to clean the IAC and test the TPS/replace if bad, I just wondered if these two issues might be related. I have also been checking for vacuum leaks - found none so far.

 

welcome to df...

yes, they are most likely related... the tps will get noisy and cause the torque converter to lock & un-lock. if this is what your seeing, swap it out and it should be good to go.

 

Thanks for the qwik response. Just to clarify- I have a manual Trans. no torque converter. Same diagnosis?

 

yup, that would be the only way you'd see it.... cruise control

 

O.K. Update for ya. Cleaned IAC( sooty but no hard deposits) replaced TPS(jerky readings when working throttle) Checked intake plenum gasket-O.K.(replaced a year and a half ago) Engine still jumps up a hundred rpm or so when I push in the clutch to make a stop somtimes and then it drops to 500rpm and back up to maybe 700 or so before settling in around 600 rpm at idle. Tested IAT sensor a month ago- reads good - should I clean it? Could it be the O2 sensor? Doesn't really affect drivability but it makes me wonder and it probably hurts gas milage a bit.

 

my mustang used to do that when it had a vacuum leak. when you put in the clutch the motor has a sudden extreme drop in vacuum, then compensates

 

reset the PCM before you do anything else... let the comp re-learn the motor with the clean IAC & new TPS. I'll be it'll be fine. but if you do want some maintanance to do.. you can yank the o2 sensors & clean them with CRC electronic parts cleaner from the auto parts store. spray into the holes where the exhaust stream enters the sensor. spray alot. spray all the holes. let it dry & then re-install. o2's fail because they cannot get enough exhaust flow to measure for the air. clean it every 20~30k and they will last longer and perform better.

 

I was wondering this morning if I needed to reset the PCM. Now I know. Thanks a bunch for the help! This forum is great!

 

when you reset the pcm, it re-learns everything. including the new tps you installed. if you dont, it'll still take a couple of hundred miles to relearn the new stuff but may act funny depending on what you replaced.