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1990 Ford Bronco RPM Flucuation during cold start

Tiny
BLAZER99
  • MEMBER
  • 1990 FORD BRONCO
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 11,500 MILES
Why does my vehicle RPM go up and down during cold start ups? And then the RPM level goes back to normal setting.
Thursday, February 28th, 2008 AT 5:11 PM

2 Replies

Tiny
MASTERTECHTIM
  • MECHANIC
  • 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.
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Thursday, February 28th, 2008 AT 5:14 PM
Tiny
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
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Monday, March 3rd, 2008 AT 7:08 AM

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