Mechanics

RPM SEEMS TO RUN HIGH

2002 Dodge Durango

Engine Performance problem
2002 Dodge Durango V8 Two Wheel Drive Automatic 85000 miles

02 Durango / 4.7 lit-2wl dr. Vehicle idles @ 750 RPM constant w/ A/C on-(No problem with idle) When driving 40 mph, tach shows 1400rpm and it never seems to slow down when you let off accelerator--it just keeps rolling at same speed, making it very difficult on brakes because it seems to take quite alot of braking to slow vehicle-especially to STOP. I can feel torque converter bump a couple of times just before a complete stop, as if it is compensating for higher than normal rpm. Also, while driving 55 mph or more, when you completely decelerate, the tach increases a bit -then drops to 1000 or so, then increases again until it finds a comfort zone, then remains constant, ie: you feel vehicle surge a bit then slow down, pick up mph, then constant. Replaced TPS-Mopar OEM, checked vacuum lines (visably). I'll need new brakes real soon if not fixed-this thing just does not slow itself down! Sure would appreciate your expert advice. Thanks!
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Nrpcb
May 13, 2009.




Hi
When you get it stoped does idle come back to 750?
Have you checked throttle cable for sticking? Has throttle body been cleaned? If you blip the throttle in park does it stay up or retun to normal idle?
Let me know
Thanks for donate

Docfixit
May 13, 2009.
Yes, when I am stopped, the tach goes to 750-steady. Throttle cable appears to be free and working fine. I manually actuated the throttle/butterfly with cover off inside engine compartment. No, throttle boby has never been cleaned, but butterfly valve appears to move freely. If I blip the thottle in park, it does return to idle @750rpm. Note: the excessive rpm appears to be in sync with transmission and/or speed of vehicle--Speed sensor in transmission? Is this a symptom?I don't know if it's coinsidental or not, but I seemed to have had this problem shortly after I by-passed heater core, just looping In-Out hoses to eliminate excessive heat in the interior while A/C is running. I do this every yr. Water did run out of heater core. Thanks for whatever possibility you can come up with! Thanks for you reply and HELP

Tiny
Nrpcb
May 13, 2009.
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Tiny
Nrpcb
May 14, 2009.
Think what might be happening is trans related. Lock-up clutch in torque maybe staying applied. This would keep trans from down shift ie. Hard down when you get it stoped. Need to have trans scanned to see if that is happening.
Let me know

Docfixit
May 15, 2009.

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