high idle

[sdoyle]

90' Cherokee 4.0L
What is the normal nuetral idle rpm? I am running at 1500 and it seems very high. What is the most likely problem causing this high idle? Thanks in advance.

[AlohaBra]

Originally Posted by sdoyle

90' Cherokee 4.0L
What is the normal nuetral idle rpm? I am running at 1500 and it seems very high. What is the most likely problem causing this high idle? Thanks in advance.

750rpm would be perfect...800 is OK.
Be careful....on my 84 the throttle cable fitting broke off and the cable cut a slit in the firewall sheet metal and was hanging up.
Now in you case, it could be anything, so the first thing is to check the throttle cable and cruise control connections. Are you carb or port injected? Vaccum line leakage should be checked also....listen for hissing. Isn't your 4wd vaccum actuated also?

[kmerian]

Originally Posted by sdoyle

90' Cherokee 4.0L
What is the normal nuetral idle rpm? I am running at 1500 and it seems very high. What is the most likely problem causing this high idle? Thanks in advance.

My 89 was doing that, replaced the MAP sensor and that took care of it. When it is idling high, disconnect the vacuum line from the MAP sensor. if it idles down, that is more than likely your problem.