Here's my problem:
I am bringing an old '89 Cherokee Pioneer 4.0L Automatic back to life while I rebuild my '87 Laredo 4.0L engine (got about 250,000 mile on it before it died). The '89 Pioneer was very clean inside and body straight, but the engine compartment was a horrible dirty mess.
The problem is that, when I cold start, it runs fine (about 1200 rpm), then after about 46-60 seconds, rpm's drop badly to near stall (200 rmp's or so) and runs rough. After it warms up, runs fine, smooth acceleration and has plenty of power AND just passed California Smog Test.
Also, after a good run when warm, if I stop and shut down engine for
10-15 minutes or so and restart, it runs super rough (like on half the cylinders) until warm and reving the engine again.Here's what I've done:
Thoroughly cleaned all connectors (TPS, IAC, CPS, O2 Sensor, Relays) and anything I could see and get my hands on.
Thoroughly cleaned Throttle Body, IAC and IAC Port, Idle Air Port, and re-installed TBS with new gasket.
Tightened exhaust/manifold bolts. They were a bit loose.
Replaced MAP sensor with new part.
Have tried two different used but cleaned IAC's. Same result.
Compression is 140-150 cold on all cylinders.
Set TPS to spec.
New Distributor Cap, Wires, Plugs.
Brakes and Booster seem OK (though the fluid was, still is, mocka brown. Full flush is next on the list of to do's). Though when in neutral, pumping the breaks causes about a 300 rpm increase. Is that normal? hmmm...
O2 sensor test reads 6 ohm. Dead center on spec.
EGR valve appears to be working OK. By the way, the 89 has a smaller EGR than my 87 and it has a Regulator upstream of the EGR. Is this the correct configuration? My Vacuum diagragm (chiltons) does not show the Regulator but the Jeep Dealer says its fine. hmmm...
Any ideas what could be causing this problem? I sure could used your help with this one.
One other aggrevation, the Fuel Gage at 1/8th tank still has about 6 gallons in it. Any way to adjust the gage in the dash?
Thanks in advance...
Mark
PS: First time on the list.. Thanks guys (and gals), it's a great help!!!