1998 Ford Ranger races up between shifts

My ranger with 2.5l engine, races up between shifts and when the clutch is depressed, sometimes over 3k rpm. Any thoughts? I changed idle speed solenoid.

Could be a small vacuum leak that the ECU is able to compensate for at idle but doesn’t consider when cruising. There are different fuel trims for idle cruise and some even have a third for wot. Do the RPMs surge and stay high or just creep up for 5-10 seconds then drop back down? Your car is OBD2 compliant. My best advice if you have a laptio or a smart phone is to get a cheap OBD2 reader that can pool sensor data. They can be had for 20$ online. Make sure your fuel trims are within 3%± of 0. You may also have a sensor that is out of spec providing incorrect information to the ECU.

There may be a problem with the clutch pedal position switch.

This switch not only prevents the engine from starting unless the clutch pedal is depressed, It also sends a signal to the speed control servo/amplifier when the clutch pedal is depressed.


Thanks for the reply, sorry I took so long in getting back, tried a couple other things and wanted to run it to make sure of the readings.
It now surges up about 3 to 4 hundred rpm when clutch is depressed while driving, between shifts. When coming to a stop with either clutch in or transmission in neutral it idles around 1400 rpm until iam at a complete stop, the and only then drops to 850-900 rpms.

I cannot find a code or a vacuum leak. Am thinking of ordering a new MAF and harness, this one has been cleaned but it just seems like its issue. What are your thoughts?

Thanks again.


The RPMs are going to be just a tad high until you come to a stop to help energize the power assisted steering and other automotive systems that are dependent on engine RPM. I will however say that 800 and 1400 while coasting sounds a bit high. It should be closer to 700 and 1000-1200 while coasting. I have seen a little loose vacuum hose cause an idle of 3000 so if it is a vacuum leak it absolutely won’t be large at all. When coasting longer distances 15+ seconds at a time does it eventually fix itself even part way?

No in fact while coasting it never goes as low as 800 rpm it maintains between 1200 & 1400 until it is at a dead stop, not even 1/2 mile an hour won’t allow it to be at normal idle. It has never run anything like this in the past. I will go over the vacuum lines again.
It used to drop in rpm in between shifts and while coasting was always at around 750.

One of the reasons I thought it might still be related to the MAF is the fact that the idle doesn’t drop until it is not moving at all.

The only issue with that is that vehicle speed shouldn’t effect the amount of air your engine ingests other than something programmed into the ECU unless your at high speed with a intake scoop of some sort to force air through the intake. Have you recently performed any procedure that required the loosening or removal of the throttle body or intake manifold? How are your air fuel trims?