Faster idle from cold, W164 ML350

[xpack]

Hope you can help with my 2010 ML350, 3ltr V6, W164 guys and gals:- I've just owned my car for 2 months now and love it but on start up from cold the engine will idle at 850rpm eventually it will fall back to 700rpm but it seems to take ages even after the engine has warmed up and after about 5miles of driving. If it is idling at 850rpm and I turn the engine off and restart, it will idle at 700rpm. Is this normal or is something going on that needs investigating., Car has done 94,000mls.
thanks.

 

[fabes]

Just to check, is it a Diesel?

Any secondary issues, lumpiness, lag on throttle etc?

As you've only had it two months have you thought about taking it back to the selling garage where they can read codes and see if there is anything there?

 

[xpack]

Just to check, is it a Diesel?

Any secondary issues, lumpiness, lag on throttle etc?

As you've only had it two months have you thought about taking it back to the selling garage where they can read codes and see if there is anything there?

Yes it's a diesel, unfortunately it was a private sale, car drives perfect, smooth power delivery, no lag and no codes I have my own Autel MK808 obd diagnostic. This is just a little niggle that seems to have got a bit worse now the weather is a bit colder.

 

[fabes]

Diesels do take longer to warm up and a little higher idle is a very minor niggle in comparison to some of the issues diesels can slap you in the face with - but you know that.

With no codes from your reader to steer you and I presume fresh fuel in it everal times by now, if it still niggles you could pay a good local MB indi (not a dealer) to put it on their STAR.

Comments from another owner are what you're after on here though in case 'they all do that sir.....'

 

[Dean Fletcher]

Yes it's a diesel, unfortunately it was a private sale, car drives perfect, smooth power delivery, no lag and no codes I have my own Autel MK808 obd diagnostic. This is just a little niggle that seems to have got a bit worse now the weather is a bit colder.

My old diesel sounded like a tractor on a cold morning, less so in summer.

 

[star]

These have a battery sensor that raises the idle if the battery is low and the car should reach just anove the 80 degree mark when driving, most prob a stat fault for slow to get hot.

 

[ajlsl600]

Well pointed out.

 

[Snake Charmer]

Would a W164 be fitted with a PTC heater like my S211 E320CDI? When mine deems to work the rpm rises to give the alternator an advantage.

 

[xpack]

Thanks for that, very helpful. I have purchased a new thermostat and thought it would be an easy fix but one of the three bolts is very long and doesn't come out, it hit against a metal part which I would reckon would need to be removed or is there a way round this to get that bolt out?

 

[xpack]

A thing I have noticed is that as soon as engine is started in morning warm air comes from vents within 30 seconds or so which is unusual for a diesel.

 

[Snake Charmer]

A thing I have noticed is that as soon as engine is started in morning warm air comes from vents within 30 seconds or so which is unusual for a diesel.

It must have the PTC heater then, that may be the reason your rpm rises.