My rpm's are humping!!

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11-25-2009, 04:54 PM

Jeepin91XJ

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Year: 1991

Model: Cherokee

Engine: 4.0 l

My rpm's are humping!!

When coasting at say 60mph my rpm's go up and down between say 1600 and 1800 rpm..It goes up and down at a steady even pace but idles perfectly..Any ideas on my humping xj?BTW it's a 1991 larado 130kmiles with auto aw4..

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11-25-2009, 05:38 PM

Willys55

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Model: Grand Cherokee

1 st. the term is HUNTING

2 nd. either your torque convertor is bad or your output speed sensor is shorted to ground.

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11-25-2009, 05:40 PM

Jeepin91XJ

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Year: 1991

Model: Cherokee

Engine: 4.0 l

Quote:

Originally Posted by Willys55

1 st. the term is HUNTING

2 nd. either your torque convertor is bad or your output speed sensor is shorted to ground.

Where is this output speed sensor located?Tail shaft perhaps?

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11-25-2009, 06:27 PM

prerunner1982

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Year: 1993

Model: Cherokee

Engine: 4.0 ltr

Quote:

Originally Posted by Willys55

1 st. the term is HUNTING

Are you sure? Going up and down sounds like humping to me...

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11-25-2009, 06:55 PM

SeriousOffroad

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Model: Cherokee

Or the T/C is locking and unlocking. Next time it happens use your left foot to lift the brake pedal and see if the surging goes away.

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11-25-2009, 08:43 PM

Jeepin91XJ

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Year: 1991

Model: Cherokee

Engine: 4.0 l

Quote:

Originally Posted by FrankZ

Or the T/C is locking and unlocking. Next time it happens use your left foot to lift the brake pedal and see if the surging goes away.

Will try that FrankZ..How a bout a vacume leak?It idles just fine tho..Humm?

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11-25-2009, 09:01 PM

SeriousOffroad

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Model: Cherokee

When my 97 had this problem is was a misadjusted brakelight switch. The torque converter lock circuit goes through the switch. Step on the brakes and the T/C unlocks.

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