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2000 Ford Explorer fluctuating RPMs
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DudeJay7
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Mar 27, 2015, 5:38 PM
Post #1 of 12
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2000 Ford Explorer fluctuating RPMs
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2000 Ford Explorer V8 5.0 AWD 171,xxx miles
I bought a 2000 Ford Explorer from a auction and it had a check engine light on for a camshaft position sensor. It started doing this when I bought it, the RPM will fluctuate from 1000 RPM and to around 4500 RPM. Sometimes when I start the SUV it will be under 1000 RPM and other times it will start and go right to 4500 RPM. This is when its warmed up or cold. While I'm driving it will sometimes drop for awhile and go back to 1000 RPM even when I'm driving on the interstate going about 70 MPH.
I've replaced the camshaft position sensor and the air control valve. The codes have cleared for the camshaft position sensor after I changed it.
It needs the EGR valve, EGR tube, both exhaust manifolds, and master brake cylinder put on but I wouldn't think this would cause this weird. I'm having these all put on tomorrow. So I hope it fixes it but I don't think it will.
When driving I don't notice that engine changes in sound at all. When the RPM go up and down I don't lose any power while driving.
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 27, 2015, 5:55 PM
Post #2 of 12
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Re: 2000 Ford Explorer fluctuating RPMs
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That is a huge surge. While it is surging up to 4500 rpm and you unplug the IAC electrical connector what happens?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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DudeJay7
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Mar 27, 2015, 5:59 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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I had it taken to a mechanic that replaced the intake air control valve. He was the person that showed me my egr tube wasn't connected to the egr valve any longer. The tachometer goes up but I don't feel any difference when driving.
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Discretesignals
Ultimate Carjunky
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Mar 27, 2015, 6:03 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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When you start the engine and the tach registers 4500 rpm is the engine actually revving that high? I didn't think the IAC could allow the engine to get that high even if it was stuck open.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Mar 27, 2015, 6:06 PM)
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DudeJay7
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Mar 27, 2015, 6:13 PM
Post #5 of 12
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Re: 2000 Ford Explorer fluctuating RPMs
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No I don't think it is actually at that high of rpms. Because it will jump from 4500 down to 700. While driving so I don't think it is actually surge. The tach seems to fluctuate a lot.
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DudeJay7
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Mar 27, 2015, 6:14 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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Sometime when I start the car it goes right to 4500 rpm but it doesn't seem to be actually running at those rpms
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Discretesignals
Ultimate Carjunky
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Mar 27, 2015, 6:25 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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So, actually there is a problem with the tachometer and not the engine. Replacing the IAC valve won't fix a tachometer that isn't registering correctly.
Tachometer gets its signal from the engine computer. If you had a scan tool that has data stream information, you could watch the data value for the engine rpm and see if it matches the tachometer.
For example if the engine computer data value shows the engine rpm at 700 rpm and the tachometer shows 4500 rpm, you either have a gauge issue or some type of electrical interference going on.
If the engine rpm in the data value shows 4500 rpm and the tachometer shows the same, but the engine isn't revved that high, you need to look at engine speed signal inputs that come from the cam and crank sensors. I really don't think it is a speed/position sensor input because the running of the engine would be affected.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Mar 27, 2015, 6:27 PM)
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DudeJay7
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Mar 27, 2015, 6:41 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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Do you know if autozones scan tool are able to scan the rpms or is it a different type of scan tool needed to check this?
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Discretesignals
Ultimate Carjunky
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Mar 27, 2015, 6:49 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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Really not too sure if Autozone's house scanner/ code reader has data stream capabilities. I suspect they use a code reader. They do sell cheap scanners for under $100 that have OBD 2 data stream capabilities or you can have your mechanic check it out if he/she has the equipment.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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DudeJay7
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Mar 27, 2015, 6:53 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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Thanks for all the help. This will put me in a good direction.
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Discretesignals
Ultimate Carjunky
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Mar 27, 2015, 7:01 PM
Post #11 of 12
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Re: 2000 Ford Explorer fluctuating RPMs
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Your welcome. Let us know how things turn out.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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DudeJay7
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May 12, 2015, 8:50 PM
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Re: 2000 Ford Explorer fluctuating RPMs
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My tachometer isn't working right I had a guy hook a scanner to it and the tachometer was showing 4000 rpm but the scanner was showing 1000 rpm.
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