Problem's with the '00 Pajero/Montero (6G72 3.0L V6). When driving, the engine is ever so smooth and responsive. Come to a stop, it's smooth for a short while and then the whole car vibrates with the engine (mounts are new, replaced in September). It's more noticable in drive, although it intermittently shakes the vehicle pretty harshly in neutral. To avoid this, I have to shift into neutral and raise the revs to 900 or so rpm.
The engine rpm is constant and does not fluctuate at all. Although sometimes when you shift into drive or reverse, the rpm drops below 500, shaking the car backwards or forward depending on gear. Also, if I was to release the brake pedal with the shifter in drive and allow the vehicle to move forward, it shakes badly as it moves forward. Give it some gas and it moves very smoothly.
My first step was to go back to the basics and pull the plugs. They all looked fine and very clean. Next, I pulled the wires with the engine running, to see if it was an ignition related problem. It wasn't. I replaced the fuel filter earlier than I do (usually every 25,000 miles this one had less than 18,000 miles) and it's still the same. I cleaned the MAF, throttle body and IAC valve (even replaced its o-ring)...nothing's improved.
I thought maybe it's the fuel pressure, and had it tested...it was within spec and I was told if it was fuel pressure, it would affect driveability. The injector insulators are also new (replaced back in September), so I doubt they are the cause. I regularly run TC-W3 in the fuel, and fuel system cleaner before every oil change, so I'm ruling out dirty injectors...but I'm not sure if one of the injectors is faulty. If one was faulty, again would it not affect drivability? I also reckoned it could be the IAC, but would the rpm not fluctuate if it was the cause?
The only other thing that springs to mind is a vacuum leak. But acceleration and performance is unaffected...would that not have an affect to some extent? I'm thinking the problem may be with the TPS (running on the factory one at 190,000 miles), because there are dead spots (especially at 2,100 rpm) but I'm wondering if anybody has any other ideas.
Thanks very much!
The engine rpm is constant and does not fluctuate at all. Although sometimes when you shift into drive or reverse, the rpm drops below 500, shaking the car backwards or forward depending on gear. Also, if I was to release the brake pedal with the shifter in drive and allow the vehicle to move forward, it shakes badly as it moves forward. Give it some gas and it moves very smoothly.
My first step was to go back to the basics and pull the plugs. They all looked fine and very clean. Next, I pulled the wires with the engine running, to see if it was an ignition related problem. It wasn't. I replaced the fuel filter earlier than I do (usually every 25,000 miles this one had less than 18,000 miles) and it's still the same. I cleaned the MAF, throttle body and IAC valve (even replaced its o-ring)...nothing's improved.
I thought maybe it's the fuel pressure, and had it tested...it was within spec and I was told if it was fuel pressure, it would affect driveability. The injector insulators are also new (replaced back in September), so I doubt they are the cause. I regularly run TC-W3 in the fuel, and fuel system cleaner before every oil change, so I'm ruling out dirty injectors...but I'm not sure if one of the injectors is faulty. If one was faulty, again would it not affect drivability? I also reckoned it could be the IAC, but would the rpm not fluctuate if it was the cause?
The only other thing that springs to mind is a vacuum leak. But acceleration and performance is unaffected...would that not have an affect to some extent? I'm thinking the problem may be with the TPS (running on the factory one at 190,000 miles), because there are dead spots (especially at 2,100 rpm) but I'm wondering if anybody has any other ideas.
