1990 Ford Bronco RPM Flucuation during cold start

1990 FORD BRONCO
11,500 MILES • 6 CYL • 4WD • AUTOMATIC
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BLAZER99
  • MEMBER
  • 2 POSTS
Why does my vehicle RPM go up and down during cold start ups? And then the RPM level goes back to normal setting.
Feb 28, 2008 at 5:11 PM
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MASTERTECHTIM
  • CERTIFIED EXPERT
  • 4,750 POSTS
several things could cause this. i would start by cleaning throttle body and idle air control valve. possible faulty coolant temp sensor.
Feb 28, 2008 at 5:14 PM
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CFBRONCO19
  • MEMBER
  • 15 POSTS
I had the same problem and i spent 4 months with it, after replacing a couple parts that werent it, it ended up being the M.A.P. sensor in the end once i put the new map sensor the problem went away completely
Mar 3, 2008 at 7:08 AM
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