Rough idle when stationary

[Overthehill]

Thank you Dave for helping me to get started.
I have a stock standard NT 2011 3.2 auto, regularly serviced by Mitsubishi until the last one by RACT. It has done approx. 155000ks, some towing a 2.4 tn caravan.
About the 70000ks mark I noticed, eg, stop at lights, foot on brake and in drive the car would occasionally vibrate, as if firing on 3 cylinders. Cutting a long story short, the Hobart Mitsubishi service say there is a problem but do not know where it is, engine or even the gearbox.
Symptoms which are regular now.
Stop the car, leave in gear and it shudders/vibrates, let it roll forward say over 2ks per hr. and it stops or when stationary I put it in neutral to stop the problem.
Moving the gear lever to manual and even selecting 2nd, or have the aircon on to increase revs. still vibrates. In park no vibrations, in reverse, once or twice over the last 3/4 years.
The RACT service chap slightly jacked up the engine whilst running, still vibrated. He then put the jack under the gearbox and he said it stopped and suggested check the gearbox mounts. I have and they seem to be ok. Has any one any ideas ????

[craka]

Mounts and dynamic dampners on the cross member that runs under the auto been checked?

[erad]

How long since the transmission fluid was changed? And what was used to replace the fluid?

Reason I ask, I had Range Rover with the Chrysler Torqueflight transmission. Horrible 3 speed arrangement. Specified fluid was Dexron II. One change, I couldn't get any Dexron II - I could only get DexronIII. Later fluid spec - it must be higher spec and therefore better for me.... WRONG!

The transmission changes were far better - crisper and more direct. It felt great until I put the beast into reverse when it was cold. It was a case of Grab/Slip/Grab/Slip/Grab/Slip all the way out my driveway. Run it for 10 minutes and all was good. In drive it was good. I phoned Mobil and asked them what was happening. They told me that Dexron III had different frictional properties than Dexron II. It sounds to me as if someone has used the wrong fluid in your vehicle.

[geopaj]

It’s not common but is also not totally uncommon either.

I would be suspecting either engine/gearbox mounts and/or suction control valve (SCV).

I would consult with a local diesel specialist - rather than Mitsubishi

[spot01]

I've had 5 of the Gen 4 cars - a couple had rougher idle (in gear) than the others. I asked them to check the idle speed - they upped it slightly & that fixed one car. Another car was better after a couple of doses of injector cleaner. Note none of the cars were above 30,000km.

Simple things first:

Have you tried some injector cleaner?

Has the inlet manifold been checked for coking?

Did they check the idle speed is as per spec?
- what is the idle speed, warm, in N, stationary?
- what is the idle speed, warm, in D, stationary?
(photos of tacho showing speed will do)

Does it do it cold?
Does it still do it if you very slightly increase the revs, warm, in N, stationary? (no A/C, as whilst this increases revs, it also put more load on the engine).

[Overthehill]

Rough idle when stationary

Thanks guys for quick response and ideas.
It prob started to happen at about 55000k so I gather it had the original oil since new.
Injector cleaning has been done several times, no change.
Mounts and dynamic dampeners I will check very soon.
When stationary I have turned the air con on, revs increase, ever so slightly but still no better.
Left foot on brake and increase revs with accelerator, vibration gets rougher, have not gone past approx 850revs.
Idle is around 650revs
There is generally no changes if hot or cold,except first thing occasionally on a cold Hobart morning and then it feels running on 2 cylinders.
There is a chap who specialises in gear boxes and as suggested might go and see if he can check/service it.
First will check mounts. Cheers
Overthehill

[Little Devil]

I'd be real worried if my vehicle still had the original oil in it at 55,000km

[Quietguy]

Thank you Dave for helping me to get started.
I have a stock standard NT 2011 3.2 auto, regularly serviced by Mitsubishi until the last one by RACT. It has done approx. 155000ks, some towing a 2.4 tn caravan.
About the 70000ks mark I noticed, eg, stop at lights, foot on brake and in drive the car would occasionally vibrate, as if firing on 3 cylinders. Cutting a long story short, the Hobart Mitsubishi service say there is a problem but do not know where it is, engine or even the gearbox.
Symptoms which are regular now.
Stop the car, leave in gear and it shudders/vibrates, let it roll forward say over 2ks per hr. and it stops or when stationary I put it in neutral to stop the problem.
Moving the gear lever to manual and even selecting 2nd, or have the aircon on to increase revs. still vibrates. In park no vibrations, in reverse, once or twice over the last 3/4 years.
The RACT service chap slightly jacked up the engine whilst running, still vibrated. He then put the jack under the gearbox and he said it stopped and suggested check the gearbox mounts. I have and they seem to be ok. Has any one any ideas ????

Sorry, no ideas but my NW does the same thing - asked the dealer to fix it on each of three last services, and each time they claimed it was done, but the damn thing still often idles like a mack truck. Also asked them to adjust the hand brake,but it doesn't hold the truck when in gear and idling.

David

[erad]

Overthehill wrote "Left foot on brake and increase revs with accelerator, vibration gets rougher, have not gone past approx 850revs..

This seems to me as if the torque converter is grabbing - trying to drive the car but doesn't have enough power to sustain the drive at that speed (Fair enough). It is a case of grip/slip. Give it a bit more accelerator and it gets worse. Change the transmission fluid.

[MrIsuzu1]

Mate had the same thing with his NT 3.2 auto. Turned out to be the engine mounts.

[tomwithannl]

I'd be real worried if my vehicle still had the original oil in it at 55,000km

I am sure "overthehill" is referring to the auto trans fluid.

Tom

[Paj11]

I went through this last year, engine mounts replaced, now a different car.

[Doowrag]

Mine has also started vibrating pretty bad at idle. In Park, Drive, Reverse doesn't seem to matter. May be coincidence but it happened on the day i got my lift kit installed a couple months ago. As soon as i drove it I noticed it. The next day i ran it out of diesel but that's another story

I now run Fuel Doctor regularly, and have since had the Intake Manifold Cleaned and Suction Control Valve Replaced with no improvement. When the revs are slightly above idle it goes away. I've been to a Diesel expert and my local mechanic with no definite solution. Gearbox was serviced (properly) by an an expert around two years ago.

I'm told the engine mounts are fluid and there is no way to check if they are stuffed without pulling them out... and obviously if you pull them out you might as well replace them...

Any other ideas before i go the Engine Mount Path? it drives me INSANE...

[nj swb]

I'm told the engine mounts are fluid and there is no way to check if they are stuffed without pulling them out... and obviously if you pull them out you might as well replace them...

I bought a wrecked NW for my Shorty project, and the engine mounts are fairly conventional metal and rubber. One was broken, and the other damaged, so I bought two replacements - through Bursons, but otherwise identical in appearance / construction to the mounts that came in the NW.

[Doowrag]

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