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How high do you guy's XJ's idle at

BIGSLVRXJ

BIGSLVRXJ

NAXJA Forum User
Location
Des Moines, Iowa
My 90 4.0 AW4 idles at about 1000 rpms. And about 800 when the A/C is on. How bout you guys. Also when going highway speed(55) what rpms are you at?
 
My air don't work. :cry:
The initial start it idles at 975-1000 after two-four mins of warming up it drops to 750.


On the highway roughly sits around 1750-1900.


______________________
'91, XJ
 
About your air dont feel too bad mine is jacked up. I put 134 in on top of 12 so its all messed up. I wonder why mine is idling so high. EGR Valve is replaced. Maybe its time to do the famous "Jeep Throttle Body Cleaning." Anyone have any ideas?
 
It should idle from 600-800 rpms. A high idle is normally a sign of a vacuum leak. Check your hoses, especially where they run under the battery. Mine had a bad vacuum brake booster. When you turn on the heater, do you get defrost only? That is also a sign of a vacuum leak.
 
Normally 600 ish and always over 1000 on startup but sometimes over 2000 and it doesn't wanna go down unless I shut off and restart or hit the gas on and off a few times... Going to clean the throttle body and see if that helps. 87 I6
 
My 87 4.0 idles at around 700-800 mosat of the time. No AC, but it does have a block heater. Don't remember what the 96 4.0 idles at, but it is also pretty low. It does have AC, although we don't use it much after leaving Atlanta for New Hampshire.

Copperhead

1987 Laredo 4.0, 4wd, 2door, 280,000km
1996 Sport 4.0, 2wd, 4door, 160,000mi
 
Mine does this:

from a cold crank:
idles about 750 the first two minutes, then over a space of the next 5 minutes or so it raises to 1500 rpm or so. Will stay here for about 10 minutes, after which it'll drop back down to 600 rpm and give no more problems.

I've done:
-new TPS
-TB cleaning
-new IAC and clean out of it's chamber in TB
-new O2 <recall work>

I've observed:
-17" of vacuum, and very stable- no more than a 2 psi rise/drop and then immediate return to 17" upon sudden open/close of the throttle plate. <one could presume no vacuum leaks, then>

Anyone got ideas?
 
BTW- vehicle is a 90 XJ, 4.0, AW4. Also new ECU, ignition module and coil, and CPS
 
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