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Question: 1999 Mitsubishi Montero  mileage: 109,210. My truck was working fine but due for a major tune up. I took it into SpeeDee tune and they performed the work. When I picked up my truck it drove fine for about 20 minutes. Then when I came to a stop I noticed my truck's idle was very high and fluctuating - from 2500 to 3500 RPMs. The idle should be between 500 and 1500 RPMs ideal is at 750 according to my manual. I took it back to them and they adjusted the throttle. I drove off again and in 20 minutes my idle was at 4500 RPMs. I found a mechanic at 6:30 PM on Saturday, Memorial day weekend, I slipped him $60.00 - he said the distributor was anywhere from 45 to 90 degrees out of position and for the adjustments they made to my throttle they should have been fired. I brought my truck back in today and again they did the timing and adjusted the throttle. They hooked it up to the diagnostic and nothing came up as a problem. Lo and behold, 30 minutes of driving it out of the shop my truck's idle was back to fluctuating between 2500 and 3500 RPMs. Any ides what they could have done during the major tune up to cause this? As the problem was not there before the major tune up? Vacuum hose? Throttle sensor? It has to be something that builds up pressure since it only starts acting up after 20 to 30 minutes of driving. I am baffled I really hope you can help.

Answer:  If a strong fuel injection cleaner was used on the fuel system it may have burned out the Oxygen sensor. Please understand that Oxygen sensors do fail and if it was close to failing at the time a fuel injection cleaner was used, the cleaner would have been enough to push it over the hill. Replacing the Oxygen sensor in this case should remedy your problem.

Question: 1998 Mitsubishi Montero  mileage: 246,000. I have a very high mileage (246K) Mitsubishi truck that just recently developed a problem. It seems to jerk like it is struggling or missing at times. This occurs only occasionally maybe 3 or 4 times a day during a 40-mile day of in town driving running errands. It happens at cruising speeds or under load going up hill usually in the afternoon. The symptoms usually last for 4 or 5 seconds and disappear after changing gears or engine rpm. If I mash on the gas pedal during the jerking, it makes it worse and it will not accelerate and the back and forth jerking motion gets worse but it usually clears up after letting up on the gas. The engine runs fine at idle, starts up fine, and even though the engine is tired, it has reasonable acceleration. I initially thought the ignition coil was arching so I replaced that along with the spark plugs, wires, air filter, fuel filter, cap and rotor. It almost feels like there is an electrical problem the way it jerks back and forth and will not accelerate during the 4 or 5 seconds it does this despite pressing the accelerator. It will only happen 3 or 4 times per 40 miles or so but it getting worse. Any ideas? I hate to keep throwing parts at the problem. Maybe it's just worn out and I need to buy a new truck?

Answer: From what you have described to us, we believe your stalling problem may be cause by the fuel pump. Replacing it and the fuel filter should fix your problem.

Question: 1997 Mitsubishi Montero LS mileage: 60,000. I want to change the spark plugs, but it looks like I need to pull the fuel injection off the top to get at the plugs. Am I missing something? 1) Is it really that much work to get at the plugs? 2) It doesn't come with platinum plugs; can I use them since I have to go to so much trouble to get at them? 3) Is there a cheaper manual somewhere other than the dealer ($90)? Chilton's and Haynes don't make them for the '97.

Answer: Changing the spark plugs on the newer cars is getting more and more difficult. You do not have to pull the fuel injection off to change the plugs. Your car should be equipped with platinum plugs. A Mitchell or a specialty repair book for your make of car will have diagrams and or specifications showing what you are looking for. The manuals and books give step-by-step instructions.

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Question:  1996 Mitsubishi Montero  mileage: 84,000.  I have three problems to address: 1.  When I start the Montero I usually hear the lifters making noise until enough oil is circulating, is there a way to stop this?  2.   Sometimes it blows smoke at idle or slow speeds, it doesn't do this on the highway and acceleration has always been very good.  3.  I have a maintenance-required light on, I truly believe I hit a pre-established mileage and the light came on, is there a way to extinguish this (a switch or something?)

Answer:   1.  Try changing the oil and filter several times in 500 miles.  If possible, drain the oil with the engine at normal operating temperature.  2.  Check the PCV and Engine breathers; they may be plugged.  The valve stem seals may be failing.  3.  The switch to reset the light is located on the back of the speedometer.

Question:  1998 Mitsubishi Montero mileage: 420.00.  I was driving my Montero today and the "Check Engine" light came on. I checked the engine over and found no problem.  It wasn't overheating, it had plenty of oil and antifreeze, the oil pressure was okay, and there was no visible problem.  Do you have any idea what would cause the light to come on and stay on?  Any suggestions?

Answer:   The “check engine” light will “light” when there is a malfunction in the engine management system.  The fault code is then stored in the computer.  The computer must be scanned to retrieve these stored faults to pinpoint the malfunctioning component.  Because the check engine light indicates something is wrong, a trip to you neighborhood automobile service center sooner rather than later is recommended.

MORE: Mitsubishi Montero Repair Questions

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