1990 Jeep YJ High idle and dieseling

Tiny
FLYINGACE22
  • MEMBER
  • 1990 JEEP WANGLER YJ
  • 4 CYL
  • 4WD
  • MANUAL
  • 12,700 MILES
Has a recently installed, newly rebuilt engine. It was running fine for about 6 weeks after install, then started idling high, and shutting off hard (dieseling. Would shake and sputter before shutting off). It does this intermittently. I don't believe there are any vacuum leaks, but don't know for sure how to check. What are the most likely causes?
Tuesday, October 12th, 2010 AT 10:35 AM

3 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Its either overheating, throttle plate sticking open and idle speed to high and excessive carbon in the cylinders acting as a glow plugs and ignition timing off
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Tuesday, October 12th, 2010 AT 10:43 AM
Tiny
FLYINGACE22
  • MEMBER
  • 2 POSTS
I've only driven it 3,000 miles with new engine, and it has a new radiator as well. Is it really likely that it's overheating, or the cylinders have high carbon deposits? Is it possible that it's the throttle position sensor, or idle speed actuator motor? I've removed the throttle body housing, and it doesn't appear that the throttle plate is sticking.
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Tuesday, October 12th, 2010 AT 10:51 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Is it possible that it's the throttle position sensor, or idle speed actuator motor-could be the problem raising the idle speed
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Tuesday, October 12th, 2010 AT 11:14 AM

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