Slight misfire on idle / low revs

[gadget1960]

As title ..... I have a w210 240 v6 which has a slight mis-fire on idle and very low revs, I have cleaned the maf sensor with zero result (so .. maybe a faulty maf??) next up will be plugs and plug lead testing along with finding any potential air leaks. What I have also noticed is the gear shifting is a bit erratic but only in the lower gears and at low revs, could this be caused by the misfire? ie: variations in torque/revs messing with the shifting pattern? I heard somewhere that auto's are prone to erratic shifting if the power plant isn't on song?
When I plant the throttle it pulls like a train with no decernable mis-fire ( or none that I can feel) and seems to shift ok.
Anyone have any ideas what to look for on one of these motors?

 

[Hawkwind]

If you have a reliable independent MB specialist near you, get them to put it on their STAR diagnostic system.

It should cost around £30 and will save you a lot of time and potentially save you money, not buying parts you don't need.

Where are you located? Someone on here may know a good specialist near you.

 

[BlackC55]

Slight misfires on the 112V6 is quite common.

You may find that you will never completely remove it. That's just the way they are. I would be looking at plug leads/plugs or a slight inlet manifold leak to start with.

I expect the maf to be good as you say it pulls well.

When was the last time the ATF was changed?

 

[gadget1960]

Thanks for the replies, I'm based near Canterbury Kent, not sure if there are any specialists other than main dealers near me. as for the ATF ... not sure if and when it has been changed as I don't have a complete service history but is on my list of things to check/do along with plugs and leads.
I suppose the star check is the way to go to pin point any obvious problems, kind of odd that a MB v6 idles a little lumpy being a 'premier' brand, I've had several v6 motors in different makes of vehicles and they have all been very smooth, and by far the best was my 1974 3.0 capri !
Anyone know of a good independent close to me I can take it to and not get my pants pulled down ?
Cheers all.

 

[Hawkwind]

There are a couple of members in Kent, hopefully they will be along soon and point you in the right direction.

ATF fluid change is a good idea and good preventative maintenance, especially if you don't have a detailed service history. These auto boxes can be expensive to repair/replace, prevention is better than cure in this case

 

[Codger49]

Try Steve Garlick - Stevensons Independent Mercedes Specialists near Maidstone (01622 815 227). He replaced the gearbox TCU on my CLK280. He was a Mercedes Diagnostic Technician and is used to resolving tricky issues.

Slightly nearer to you are Class Cars in Sandwich, I have not used them, but others seem happy with their services.

 

[gadget1960]

Thanks all for the help and advice