Pulse in Engine RPM

there is a pulse in RPM's at certain speeds....usually around 50.... be driving, then a pulse of a gain of 3 to 5 degrees in RPM's momentary...2001 WJ with inline 6...4x4...sometime it will vary to certain speeds but usually around 50 ... thanks for any ideas...

Reply to
Mindy
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Do you recall if you were driving into the wind, and was it gusting ? ;>)

Reply to
Rod's work news

I'm thinking you are close to the speed where the transmission will hunt gears. Depending on the grade or winds this can be quite annoying.

Try that speed with overdrive off

Reply to
DougW

my 97 did that. Turned out to be my TPS sensor, apparently the computer thought the throttle was changing and was taking the tranny in and out of overdrive. I must have had a bad spot in the throttle position sensor at around the 55mph position.

cal

Reply to
Cal

That is a definite possiblity.

The test is to take the connector off and using a quality multimeter, measure between the center and outer pin (either one) as you slowly open/close the throttle plate. Any jumps/drops indicate a bad spot. Measure between the outer two pins and if you get an "open" then there is a break in there. You can also just measure the center pin to ground with the ignition on (engine off) and open/close the plate. In that case the voltage should vary between 200 milivolts closed and 4.8 volts wide open, with the outer two pins showing about 5 volts. (note: 2000 and later I'm not sure if that is still the case)

Reply to
DougW

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