Hi all

As I have said previously, my KH seems to shake the car when in idle, both in Drive and Neutral. I have listened to the engine, and I have watched it while idling. It seems like it is shaking rather than missing,I can still feel it in Neutral. So can it in fact be the mounts (I thought it would be mounts under load only ie Drive)

Is this what others seem to be experiencing also with their cars?

Would the timing belt do this if it was out (again though it seems to be a shake rather than a miss - exhaust sounds steady).

How do I adjust the idle? I previously adjusted the screw which lifted the idle along with in an increase in the intake noise. But it seems to have dropped again. The Gregorys suggest some thing about bridging pin 1 and 4 on the diagnostic pin and then adjust the idle screw. Is this more permanent adjustment?

Any assistance would help.

L

Check numerous previous posts re this.

Mitsubishi is aware of this fault, and one of the major causes which is the engine mounts.
They replaced some under warranty with a revised mount, but it is only a temporary fix as the rough idle returns. Mitsubishi don't seem to have a permanent fix.
If your car has it (as mine does), pretty much stuck with it.
Mitsubihsi tried everything with mine, revised mounts, adjusting idle, cleaning throttle body, but always returned. The revised mounts did help for a while, but not worth the effort unless warranty job.
Im lucky as mine goes away a fair bit by switching to neutral at traffic lights etc.
Adjusting the idle speed is only a short term fix as well, as the computer will automatically bring the idle back into line after a period of time.
So unfortunately all you can do is make sure car is well serviced, and use a high octane fuel which seems to offer a small bit of relief.

Some Holden's and Falcon's get this rough idle problem as well, so not isolated to Mitsubishi.

This has been covered many times. Type in

Lumpy idle, TH 3.5 in the search function and you will see a thread with 74 replies. Alot of discussion there.

Hi all

As I have said previously, my KH seems to shake the car when in idle, both in Drive and Neutral. I have listened to the engine, and I have watched it while idling. It seems like it is shaking rather than missing,I can still feel it in Neutral. So can it in fact be the mounts (I thought it would be mounts under load only ie Drive)

Is this what others seem to be experiencing also with their cars?

Would the timing belt do this if it was out (again though it seems to be a shake rather than a miss - exhaust sounds steady).

How do I adjust the idle? I previously adjusted the screw which lifted the idle along with in an increase in the intake noise. But it seems to have dropped again. The Gregorys suggest some thing about bridging pin 1 and 4 on the diagnostic pin and then adjust the idle screw. Is this more permanent adjustment?

Any assistance would help.

L
Considering it is a modern motor that is quite unacceptable, however it has to be considered that the construction of the mitsi V6 is similar to racing motors and as such a lumpy idle is a small price to pay for performance with economy.
My 96 3L is a bit rough at idle and I have not had a chance to dig around under the bonnet to look at wether it can be improved. At the mo I am running 91 octane but plan to change to 95 once I have some fuel consumption figures for 91.
If 95 does not improve the idle quality one of the first things I will look at is the spark plugs and SP leads. It is amazing what a bad/dodgy SP and/or SP lead will do.
Then there is the dizzy cap itself, which may need replacing.
So in short I would say rough idle has nothing to do with engine mounts, although having worn engine mounts will make the roughness more apparent.
Usally a rough idle is an inbalance in the way the fuel is burned between the different cylinders and usally this is ignition related (although valves do play an important role in this aspect as well), unless you have fuel injection problems.
I do believe that Mitsi recommends to use long life platinum plugs on the rear bank, if you have different SP's from the front and rear bank this may well cause an imbalance.
Another factor may well be that the front bank is running cooler than the rear due to getting more cooling from air flow, this is most apparent in air cooled motors such as Harley V twins (talking about rough idle:)), Triumph triples and other set ups where some cylinders get more air than others. Although with liquid cooled motors this is not such a problem. One way to try and overcome this problem is with the use of hotter or colder SP's.
Anyway have a look at what sort of SP's you have in the motor and how they look, a SP will usally tell a fairly good story about how your motor is going. I would excpect a difference in SP colouration between front and rear bank (due to heat variation) but across each bank they should all look the same.