I have a 1998 Mitsubishi Chariot Grandis imported and converted n the Philippines from Japan. It is the f94 model that is 4WD. I had one problem but now have two.
Problem One: When I am running in 3rd gear or 4th gear and slightly press the accelerator, I get a shudder in the engine. It is as if the engine is trying to come out of the car. If I give the car more gas it goes away and if I take my foot off the gas it goes away. I have checked all the engine mounts and drive train and all is fine. The car shows no codes in a computer check. I checked the plugs and they are totally fouled after only one months use. When the engine is idling it "hunts" in the rpm and varies from 600 to 800. It gets worse when I turn on the AC. Of course the hunting stops at times also and it runs fine. But always the shudder.
Problem two: On trying to figure out problem one abovie my mechanis said the rear U-joint needed to be replaced. After he did this I now have a solid vibration and noise at 80 KPH that gets worse as the speed increases. He has changed the rear u joint 2 times and it is still there. This was not happening until the u joint was changed.
Problem is most likely due to a misfiring and it could be due to the ignition coil packs or wires. You mentioned the spark plugs fouling, if they are coated with carbon and you have excessive engine oil consumption, that indicates valve seals and piston problems.
The erratic idling speed indicates a idle control fault. Get the ISC and thrpttle body cleaned and retest.
Problem 2 is due to a fault with the parts or installation of the U-joints. While replacing the U-joints, were the U-joint mountssubjected to heavy impacts while removing the joints?
How many joints were replaced and were others checked?
February, 13, 2011 AT 10:46 PM
The rear U-joint was replaced first and then I started having problem two. The first thing the mechanic insisted on doing was replacing the other two u-joints. It did not help. The mounts were hit with a hammer I am sure as that is how they took out the u-joints but I would not say it was excessive.
The car uses very little oil. About 1/2liter in almost 3000 kilometers. I will have the throttle body cleaned but what is an ISC? Sorry if that is a stupid question as I am not the most up to date on the terms here.
February, 14, 2011 AT 1:12 PM
ISC = Idle Solenoid Control Valve, most other manufacturers call it the Idle Air Control (IAC) valve.
As to the U joint, I would suggest rechecking the rear U-joint. If the mechanic did not mark the initial position, try removing the shaft and turning it 180 degrees and reinstalling.