I have mitsubishi galant 1999 model V6 engine a/t. When I shift to Park the rpm is 1000 and if i will turned on the Aircon it will be lowered to 750RPM. Same thing the aircon is turned off it will fluctuate again the rpm is 1000. And if i shift to Drive the rpm will go down to 750. Please help... Thank you very much..

If it is the original engine you can get that from the VIN number. It is the 8th character reading from left to right. https://mcarsstatic.cachefly.net/pdf/owners/support/vin-information/00VINs.pdf

the engine doesn't like the extra stress of the air con unit being run _ there is no way of fixing this _ unless you get a full engine overhaul or a secondhand engine and installed _ the engine is old and the extra pressure on it with the aircon it just cant handle it

Since voltage regulation is accomplished through the alternator, I would check that first. Since the computer will increase the rpms when you turn on the ac, to compensate for the engine power drain, you will experience some voltage increase.

Do you have a "Check Engine" light? If not, check that the accelerator cable is functioning properly. When the accelerator is in the normal position the throttle plate should be completely closed. If necessary you should remove the air duct to inspect the interior of the throttle body. The cable should be have no slack but should allow the throttle plate to close all the way.

If the throttle is working properly then I would suggest looking at the idle air control (IAC) valve which controls the idle speed when the car is in park, in neutral or in gear and the accelerator is not depressed. Try disconnecting the IAC and note how the idle is affected. This will cause a Check Engine light to turn on. To clear it, disconnect the negative battery cable for 5 minutes then start the car. Let me know what you find out.

I have a 4 cyl engine in my galant and the thermostat is found by following the LOWER radiator hose. You will need to remove the battery in order to gain access to the thermostat housing mounting bolts. There is a video on Youtube.com showing the removal and replacement of the thermostat and radiator for a 1999 mitsubishi galant.

http://youtu.be/Er1szRKrk7c

Torque converter has a splined hole that has stripped on the splined axle shaft coming out of the transmission. Because of this the power is not being transferred from engine to the transmission. You may be able to replace just the torque converter ( under $200 ) to repair the car if the splined axle shaft on the transmission is not stripped or broken. If the actual transmission is damaged the repair cost could go up astronomically.

Checked may manual for my 1990 Montero, got the following:

2.7 Liter V6 trailer max # Max tongue
w/trailer brake: 2000# 200#
w/out brake: 1000# 100#

3.0 V6
w/trailer brake 4000# 250#
w/out brake 1500# 150#


Gross weight
combined 8850 or 9291 (four door model)

In my experience (being an auto tranny in mine) I use my OD switch to let the engine run out a bit further in RPM or on slight grades to keep OD from shifting in and out.

Please let me know if this assited,
Tom

What type of car???? could be something in the computer/engine control system. if its a late model have it checked out could get worse

try cleaning earth wires