I am the owner of a 2003 Montero Sport:

- 138,000 km at present
- 3.0 l V6 engine
- AWD / 4WD version
- 4-speed automatic transmission
- transmission fluid changed only 7000 mile ago at authorized Mitsubishi dealer

My girlfriend and I bought the Montero Sport in British Columbia (Vancouver) and we traveled through the US, Mexico and Central America and shipped our car to Colombia. Right now we made it to Ecuador.
As it is hard to find a good mechanic here in South America I hope some of you could help me with a technical diagnosis.

The problem concerns the automatic transmission of the Montero Sport. I did some search here in the forum and in the manual but could not completely track down the problem:
When driving in 3rd or 4th gear at low revs (1000 - 2000 rpm) and pushing the accelerator just as much that it won't shift down I get a short but strong stutter from the gearbox. It feels like a clutch is opened and closed frequently. The problem does not occur when the engine / transmission is cold. Additionally I don't have this effect at higher revolutions or in 1st and 2nd gear. No error code is shown.

I assume that the stutter comes from one of the clutches, maybe the torque converter clutch that locks up. First I thought the clutch is worn or the corresponding Solenoid valve is malfunctioning but I don't understand why it doesn't show this effect at higher revs. (e.g. going 55 mph in 4th gear and accelerating does not lead to any problem).
I read the ECU does not lock up the torque converter until transmission reaches operating temperature and therefore I don't have the problem after startup when the transmission is cold.

What do you think might cause the problem? I will stop at a local authorized dealer in Peru but I do not want them to start working without having an idea what the problem could be. Are there any tests I can conduct myself and is there a way to manually override the torque converter lock up to stop the annoying stutter if the problem gets worse?

Your answer is highly appreciated.

Thanks you in advance!

Armin

Travel Southbound | All the way down the Panamericana

 

I am sitting here in Nazca / Peru and still have no clue. Does anyone have an idea what it could be?

Thanks guys!