1999 Isuzu Rodeo Idle RPM Fluctuates

1999 ALL OTHER MAKES ALL OTHER MODELS
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SJWITT52
  • MEMBER
  • 1 POST
I have a 99 Rodeo w/140K miles; have maintained it pretty well. Now, when starting first thing in the morn it will sometimes start & idle at over 2200 rms and not drop. If a go into drive it will try to move even with foot on brake. After it gets hot, when starting the rpms will go up & down between 1000 and 0 and sometimes stall out. Once I start driving everything is fine. So far have replaced alternator, idle pulley, throttle sensor and some thermostat guage. Am getting no computer codes. I am at a loss!
May 29, 2006 at 4:01 AM
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JOUGH626
  • ✓Experienced Mechanic
  • 55 POSTS
I had the exact same problem!!! I replaced the same things too, thinking each time tht I found the magic medicine. Some mechanic told me it could be some power steering pressure switch. Yeah right. Change your fuel filter!!! Pull your old one off and hit the ignition key a couple times to flush some fuel out of the line. Install the new filter. That should fix the problem.

Other things that should be changed on a 99 Rodeo.

Oxygen Sensors (all four!)
Spark plugs
Oil pressure sending unit

If you have any other questions, please ask.
Jun 17, 2006 at 10:06 AM
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Suggested Repair

Replace the fuel filter. Before installing the new filter, cycle the ignition a couple of times to flush fuel from the line. Also consider replacing all four oxygen sensors, the spark plugs, and the oil pressure sending unit.

Conversation Summary

The owner of a 1999 Rodeo reports cold starts that sometimes idle above 2200 rpm and try to creep in drive with the brake applied, plus hot starts where idle hunts between about 1000 and 0 rpm and can stall. Once driving, the vehicle runs normally. The alternator, idle pulley, throttle sensor, and a thermostat gauge were already replaced, and there are no computer codes. An expert who had the same symptoms recommends replacing the fuel filter and flushing the fuel line, and also lists oxygen sensors, spark plugs, and the oil pressure sending unit as items to change.

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