High rev on start problem.

[Knighthawk]

I have a 99 Explorer XLT 4x4 that revs quite high upon starting. This just started a few months ago, and I thought it might have something to do with the cold weather. But it's now hot out and it's still doing it. It revs up in the 3-4k range for about 10 seconds or so, the throttles back to normal. Any ideas on what the problem might be? I'm wonder if it might be the O2 sensor. Thanks for any inpurt

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section. Check the vacuum lines, and the intake manifold gaskets for leaks.

 

[herebyproxy]

2500

Mine runs up to 2500 for a few seconds and I thought that was high. This is after I have replaced the IAC valve, cleaned the MAS, replaced the EGR valve, replaced the coil pack, plugs, and wires. I don't remember it jumping to that speed before all this......

What can I say......it's a 'sploder...lol

 

[rego]

Cleaning the throttle body fixed my high idle problem.