Question about 1998 Mitsubishi Montero Sport
When maintaining speed at around 35 mph, with the "OD" on, the transmission will switch back and forth between the two highest gears. When set to "OD OFF" the problem goes away. This did NOT happen until recently. I am worried this may lead to something more serious and would like to address it soon. What needs repair/replacement? Who would you recommend (AAMCO, Dealership, ect.)?
I had this problem many, many years ago with a used Jeep Wagoneer. I took it to a mechanic and he told me that I should never engage the OD at less than highway speeds. He said the overdrive is designed to provide a higher gear at highway speeds to improve fuel economy and when you engage it at lower speeds, it is inefficient and the torque is too low for it to operate effectively so it drops back to a lower gear to compensate. When your speed picks up, it will re-engage the higher because it is still ON then again cycle back to the lower gear as your speed fluctuates.
After his explanation, I always left the OD off except when I was driving at highway speeds and I never had another problem except when I would occasionally forget to turn it off when I went back to "in-town" driving. Then, it only took one cycle to remind me to turn it off.
I also had this same problem with more recently with an underpowered Ford F150 conversion van and the same fix worked.
The mechanic told me that while the cycling causes extra unnecessary wear on the transmission, it ordinarily would not damage it.
Occasionally, on both vehicles, I would forget to turn the OD on at highway speeds and the difference in fuel economy was significant. The F150 would get about 8 miles to the gallon in town and 12 on the highway without OD. With OD on, the mileage would climb to 14 mpg. Don't remember the mileages for the Wagoneer but I do remember the difference being noticeable.
Posted on May 14, 2014
I would take it to 2 or 3 or more different shops and ask for an estimate to fix it.. they will probably know what causes this condition. and probably will not charge you anything.. if they want to charge you for an estimate go somewhere else. you really do not want to trust them.. When you get several estimates and several of them tell you the same thing then its a matter of who do you trust??.. Check the shops out on Yelp.. actually sounds like it could be something simple like throttle presure adjustment.. But i cannot see your car from here.
Posted on May 14, 2014
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Posted on Jan 02, 2017
SOURCE: when driving and speed goes
I have the same problem, you need to change de oil transmission or try an additive for aut. trans that resolve the problem for a while, but is almost most better changing de oil.
Posted on Feb 27, 2009
Pull the distick and smell the oil. If it's discoloured (black or dark brown) you know the transmission friction plates are burnt and needs a rebuilt.
Posted on Nov 10, 2008
Idling problems may be cause buy a number of issues. You may check out the fast idle control valve and PCV if they would need cleaning. You can check out the timing it may be advanced, that is why you feel that the car runs hard.
Posted on Jun 13, 2009
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