Mechanics

RPMS GO UP AND DOWN ABOVE 35 MPH

2000 Dodge Caravan • 150,000 miles

3.3l motor. RPMs go up and down with no consistency above about 35 at part throttle. Does not do it coasting or passing, still does it if you put it 3rd. Starts happening after the motor warms up. Gas millage is bad ( 17 hwy ). Replaced plugs, wires, and coil pack ( brought mileage up from 14). No code, hesitation, smoke, soot, etc, runs fine other wise. Only odd thing is it started not long after oil change.


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Rmdunn
February 14, 2012.



Have the cat converter checked for operation. It may be clogged. A shop can do simple testing to verify.

Roy

ASEMaster6371
Feb 14, 2012.
No one here would do it without a lot of cost so for the price of a gasket I pulled the catalytic out and checked it. No melting or clogs, in fact it is fairly clean. While there I put in a new fuel filter. I also replaced the entire ground cable from the battery. Now the RPMs on go up when you use the cruise control. Could it be the 2 speed sensors?

Tiny
Rmdunn
Feb 17, 2012.