I have a 98 ranger 4x4, with a 4.0 and automatic. of the morning when i start it up, it run's real rough for maybe a minute or so, probably not even that long, and she seem's to be idling to fast now. Any on have any idea's on what to check ? No codes are present. Any advice would be appreciated

 

I forgot to mention that the truck has 104,000 miles on it. Thank's

 

No thought's ??

 

Could be a vacuum leak!

 

Thank's steve, after reading on here about the 02 sensor's i think i am going to replace those, whatcha think ?? Just want to thank all of you good people on here, this rookie learn's alot from you all. : )

 

At your current mileage o2's wouldn't hurt but I would think they would throw a code if they were acting out to that extreme.

couple other things to check would be fuel pressure regulator and Idle air control.

 

Where is the fuel pressure regulator located at ? and how would i go about checking it ? Thank's

 

The fuel pressure regulator is located on the front of the fuel rail. There is a schrader valve nearby which allows you to measure the regualted fuel pressure. at idle the pressure should be between 35 to 40 psi. When you disconnect the vacuum line from the regualtor the pressure should jump to over 40, around 45ish. If it does not change, or the pressures are significantly higher than that, the regulator is probably faulty.

Idle air controller is more likely, and easier to replace. Remove it and clean it with some throttle body cleaner. If it improves, then that is the problem. If the problem returns, replace the idle air controller.

 

Thank's, the info from you guy's is appreciated : ) I am gonna go out in the garage and try that, raining here be a good time to do it.
Billy