Rough Start - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
Ford Bronco Forum Forum for discussion of the Ford Bronco

 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 07-18-13, 02:12 AM Thread Starter
Registered User
 
Join Date: Jul 2013
Location: Pennsylvania
Posts: 2
Rough Start

I'm new to this forum. Looking for some help. When I leave my 1991 Bronco 5.0 302 sit for a couple hours and then go to start it starts up but immediately drops to about 200 rpm sounds like it is going to stall out and then after about 1 minute it idles normal. What are everyone's thoughts on what this could be. Just recently put new plugs and wires on and changed the fuel and air filter and hasn't made a difference.

BroncoWilliam is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 07-18-13, 02:28 AM
Moderators
 
R.S.LOGAN's Avatar
 
Join Date: Apr 2007
Location: Scotland
Posts: 14,318
Re: Rough Start

Could try replacing the engine coolant temp sensor for the PCM which lets it know how much fuel needed I.e more fuel on cold start .
R.S.LOGAN is offline  
post #3 of 6 (permalink) Old 07-18-13, 02:36 AM Thread Starter
Registered User
 
Join Date: Jul 2013
Location: Pennsylvania
Posts: 2
Re: Rough Start

What is a PCM?
BroncoWilliam is offline  
post #4 of 6 (permalink) Old 07-18-13, 02:44 AM
Moderators
 
R.S.LOGAN's Avatar
 
Join Date: Apr 2007
Location: Scotland
Posts: 14,318
Re: Rough Start

Power control module .
R.S.LOGAN is offline  
post #5 of 6 (permalink) Old 07-18-13, 04:17 AM
Registered User
 
Join Date: Jul 2012
Posts: 41
Re: Rough Start

If your engine idles rough or stalls, your Ford Bronco might have a bad Manifold Air Pressure Sensor. You will have to test the MAP sensor. Follow the below steps to test the MAP sensor.

1) Locate the MAP sensor and disconnect the wiring harness from the MAP sensor. Each end of the sensor has a small tap. Pry the harness off the tap and pull the harness free of the MAP sensor.

2) Place a jumper wire between the terminals on the wiring harness and the terminals on the MAP sensor. Make sure the jumpers are bare wire and that they do not touch each other or any other metal component on the Bronco.

3) Turn the Bronco's key to the "On" position but do not start the engine. Place the leads of your multimeter onto the bare jumper wires and take a voltage reading. The voltage should reflect between 4.5 to 5.0 volts.

4) Start the engine and let it warm up to normal operating temperature. Test the voltage again. The voltage reading should be different. Have an assistant rev the engine several times. The voltage reading should fluctuate with the revving of the engine. If it does not, the MAP sensor is defective.
Jeff Collision is offline  
post #6 of 6 (permalink) Old 07-18-13, 07:53 AM
Moderators
 
R.S.LOGAN's Avatar
 
Join Date: Apr 2007
Location: Scotland
Posts: 14,318
Re: Rough Start

^ Good shout re MAP sensor .
R.S.LOGAN is offline  
Sponsored Links
Advertisement
 
Reply

  Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > Ford Trucks | Utes | Vans |SUVs | Crossovers > Ford Bronco Forum
Gear in this thread - Powered by O'Reilly Auto Parts


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome