SINCITY192

hey im new to this forum was hoping that someone could help me?

88 XJ inline 6 4.0 L
replaced TPS, like 2 weeks ago (adjustment is funny what adjust to specs) but i lowered it to as low as it would allow me to.
replaced the IAC, last summer and intake gasket,
hoses look good, and just put new map sensor yesterday

still having high idle upon start up any one know how to fix this

it revs up to about 2-3000 and sometimes stays for a couple seconds then goes down very annoying besides everyone looking at me like im about to explode its pretty scary too.

any info would be great!!!!
u guys are great

ol"blue

You check it for a vacuum leak?

SINCITY192

i guess it wouldnt hurt to check for a vacuum leak

im quite sure that its not from the manifold, being that i just change the gasket this summer that just past.

i will have to double check the hoses though

all i have to do is check every vacumm hose in the engine right?

will a vacumm leak cause the idles to rise?

also when i was driving tonight after i park the car (all warmed up) put it into park and it rev'd above 1000rpms
what could be causing this high idle?

Nick

Hey buddy,
I have been going through the same problem for a while now, and have been searching and resourcing for a solution, w/ no avail. In addition to this, My "87 XJ also has real weak starts at times. These two problems are intermittent, and never follow a schedule of appearance. I have posted on this forum multiple times recently for this prob, and no solution has arrived yet. I also have been asking the mechanics around town as well as the dealership and nobody has a for-sure answer, just speculation. Seems like our problems are rare. The one recurring thing that I am hearing is there is a "starting" sensor located behind the motor (don't know the specific name of the top of my head) on top of the trans. Evidently our 4.0s have a tendency of leaking down the back of the block, clog the sensor, and that sends it off wack. This sounds iffy I know, but with as much as I have done and spent to fix it, I'll try about anything now.
Let me know if you find out what works.

Nick

Also: NOT a vacuum leak. I was told the same, had it checked twice, and replaced all the plastic lines on top of the motor. No change whatsoever.

SINCITY192

thanks for the help nick,

i didnt think a vacumm either i would of eventually replaced all my hoses again for nothing

but i am thinking of the relays for some odd reason thinking that maybe they might be electrically shorting something from being so old (i never change them)

the sensor u mentioned wouldnt happen to be located on top of the bell housing (CPS) it thats it ive change it already, if not lets see what we can find about it!!!

to tell u the truth i really think it has something to do with the TPS because when i 1st bought one and installed without adjustin it would start with high idle and accasionally low idle here and there
then i install me old one and it was fine for a while when i bought another TPS i tried the adjustin thing but the new was way outta specs
but it starts and drives good just accasionally high idle

guess we are in the same vote