S320 CDi (W221) intermittent acceleration and kickdown

[PaulMason]

Hi, new to the site, though have been on numerous times to research an issue. My car is a 2009 S320 CDi, 154k miles. There is an intermittent fault where it goes into limp mode (I believe) and acceleration is very poor and it won't kick down (though will go through the gears on the paddles). The car had a recent gearbox oil service and was on Star, but no fault codes showed. I have also recently bought an iCarsoft MB V3 and no codes showing on that either. Having done a little research, one cause is sometimes a faulty throttle pedal potentiometer so bought a second hand unit and fitted it. This worked perfectly for about 150 miles and I thought the issue was resolved, but unfortunately the problem has returned. There is no consistency with when the problem arrives (in terms of miles, temperature or time).

My questions are as follows:

1) With the iCarsoft plugged in, is there a specific test I should run to seek out a code (its pretty new to me so I am not fully up to speed with how to use it properly)
2) In order to try and diagnose in the absence of a fault code, given there could be numerous causes, I was going to try on of the resistor plugs for the swirl pot next - its a relatively inexpensive way of potentially diagnosing if there is an issue with the swirl pot connector or motor or it being gummed up. Has anyone done this fix and are there any unintended or detrimental consequences of it that I should be aware of?
3) Does anyone have any thoughts or next steps with regards to the throttle pedal switch initially working and then seemingly not. Given the problem usually arises within 10-15 miles, I was hopeful that after 100 miles plus, across numerous journeys that it had worked? Is this simply I have bought another pedal that has an issue - I am trying to avoid the need for c. £120 for a new pedal which then may/may not work?

Many thanks in advance for any guidance shared

 

[W1ghty]

Re point 2 , the resistor fix is a very cheap easy way of ruling out the inlet port motor as an issue .
Provided the swirl flaps are in the sprung open position which is their default , the resistor works with no side effects.
Mine has been in place for over 3 years
If this sorts or highlights the correct fault , you can obviously remove it afterwards

 

[PaulMason]

Re point 2 , the resistor fix is a very cheap easy way of ruling out the inlet port motor as an issue .
Provided the swirl flaps are in the sprung open position which is their default , the resistor works with no side effects.
Mine has been in place for over 3 years
If this sorts or highlights the correct fault , you can obviously remove it afterwards

Many thanks W1ghty, apologies for my technical ignorance, but is there and easy way to see/know if the flaps are in the sprung open position? My guess is that given the car always starts and goes fine initially, they must be? Also, do you mind sharing which plug you put onto your car as there are a few on eBay and I can't differentiate between them (they range from £9 to £49).

And to your point, my aim would be to cheaply diagnose and if this fixed it, then delve further into the swirl pot connector/motor to try and fix properly

 

[W1ghty]

Swirl Valve Bypass Resistor Plug Fix Fits Mercedes V6 Diesel OM642 | eBay

This device will provide a solution to the common 'Swirl Valve Fault' that occurs on the OM642 v6 diesel engine. 2009 and later OM642 Engines will require the swirl value to be removed from the vehicle's ECU map ONLY after 2009.

www.ebay.co.uk

or these which are cheaper , but select 4.7k ohm one

1/4W Metal Film Resistors 1% 186 values available (20 Pack) *UK Seller* Free P&P | eBay

Lead length: 28mm. Case style: Axial.

www.ebay.co.uk

I can’t answer how to check the swirl flaps in advance , but if you remove the batwing air intake to see the swirl flap motor you might as well just put the resistor in place . If it works then that will tell you something in your search for the fault .

 

[PaulMason]

Swirl Valve Bypass Resistor Plug Fix Fits Mercedes V6 Diesel OM642 | eBay

This device will provide a solution to the common 'Swirl Valve Fault' that occurs on the OM642 v6 diesel engine. 2009 and later OM642 Engines will require the swirl value to be removed from the vehicle's ECU map ONLY after 2009.

www.ebay.co.uk

or these which are cheaper , but select 4.7k ohm one

1/4W Metal Film Resistors 1% 186 values available (20 Pack) *UK Seller* Free P&P | eBay

Lead length: 28mm. Case style: Axial.

www.ebay.co.uk

I can’t answer how to check the swirl flaps in advance , but if you remove the batwing air intake to see the swirl flap motor you might as well just put the resistor in place . If it works then that will tell you something in your search for the fault .

Many thanks W1ghty - I will go with the first option as the second will be blighted by my electrical incompetence. Simply plugging something in seems more akin to my ability!

 

[W1ghty]

Many thanks W1ghty - I will go with the first option as the second will be blighted by my electrical incompetence. Simply plugging something in seems more akin to my ability!

That’s why I put that one first buddy . Good luck with it all and let us know

 

[AndrewOl]

Hi Paul, sorry to hear of your problems with your S320. When it goes into limp mode, how are you getting it back to normal? Do you just cycle the ignition and it is all good? The swirl flaps generally will give a code if there is a problem, same with the throttle pedal. Guessing with modern cars is an expensive game. Was it a main dealer who had it on Star when the gearbox service was done?

 

[PaulMason]

Hi Paul, sorry to hear of your problems with your S320. When it goes into limp mode, how are you getting it back to normal? Do you just cycle the ignition and it is all good? The swirl flaps generally will give a code if there is a problem, same with the throttle pedal. Guessing with modern cars is an expensive game. Was it a main dealer who had it on Star when the gearbox service was done?

Hi Andrew, yes, just a cycle and all goes back to normal. Did 65 miles today and no issues at all, so still very intermittent. I'm going to try the swirl pot plug solution and see how I go. Yes it was a main dealer (who did some other things and have been fab so not knocking them) and haven't got anything on iCarsoft either. But, as I look at it, I still have a boat load of car for a relatively small sum, so not grumbling per say, I'm just wanting it to be as good as it can be

 

[AndrewOl]

Does sound odd as engine issues usually result in a code at least and usually a cel. When you go through each module with your scanner do you not get any stored coded at all? There is usually something insignificant or otherwise in there which can give you a clue to what is going on. If the dealer cleared all the codes though you may have nothing at the moment. A common gearbox problem does present like your fault. Limp mode with no cel that resets on an ignition cycle. If you google 7 speed automatic valve plate problems you will find lots of information. It is fixable and the usual advice is to get a star diagnosis but you have done that! Maybe ask them if they looked for gearbox faults or drive it to them when it has gone into limp without switching it off so they can see the fault in action.

 

[Larkone]

Possibly the turbo actuator playing up at that mileage and those symptoms - they get dirty inside (carbon from the motor brushes) and it gums up the gear wheels. Doesn't throw a code. You could try opening it and cleaning and re-greasing the gears (worked for a while on mine) or buy a refurb one for around £100 (TurboVanes LTD - Turbovanes LTD TurboVanesLTD) - this is what I did and it was a significant improvement in driveability and consumption. I replaced at around 150K (same engine - OM642) Mine played up after a longish run when it was hot and reset on re-starting.

 

[PaulMason]

Does sound odd as engine issues usually result in a code at least and usually a cel. When you go through each module with your scanner do you not get any stored coded at all? There is usually something insignificant or otherwise in there which can give you a clue to what is going on. If the dealer cleared all the codes though you may have nothing at the moment. A common gearbox problem does present like your fault. Limp mode with no cel that resets on an ignition cycle. If you google 7 speed automatic valve plate problems you will find lots of information. It is fixable and the usual advice is to get a star diagnosis but you have done that! Maybe ask them if they looked for gearbox faults or drive it to them when it has gone into limp without switching it off so they can see the fault in action.

Thanks Andrew, I'll perhaps clear all the faults (I know there is at least one related to the wheel speed sensor I haven't cleared yet) and recheck again after the next time it happens

 

[PaulMason]

Possibly the turbo actuator playing up at that mileage and those symptoms - they get dirty inside (carbon from the motor brushes) and it gums up the gear wheels. Doesn't throw a code. You could try opening it and cleaning and re-greasing the gears (worked for a while on mine) or buy a refurb one for around £100 (TurboVanes LTD - Turbovanes LTD TurboVanesLTD) - this is what I did and it was a significant improvement in driveability and consumption. I replaced at around 150K (same engine - OM642) Mine played up after a longish run when it was hot and reset on re-starting.

Thanks Larkone, I'll see how I go with the swirl pot and add your advice to my next check list

 

[AndrewOl]

Don’t rush to clear stored faults as they often give you (or the garage) a clue. If the fault code is current then have a look into it unless you are sure it is unrelated. Is the wheel speed sensor fault current? They can cause all sorts of fun although usually with lots of different lights on the dash!

 

[PaulMason]

Don’t rush to clear stored faults as they often give you (or the garage) a clue. If the fault code is current then have a look into it unless you are sure it is unrelated. Is the wheel speed sensor fault current? They can cause all sorts of fun although usually with lots of different lights on the dash!

The wheel speed sensor set off the abs, EPs warning, run flat, cruise and limiter wouldn't work. They all self cancelled but guessing the fault shows in history on the computer so was definitely going to clear those

 

[AndrewOl]

Sounds like you may have a few things going on which can make fault finding interesting. As with most things just try to clear one thing up at a time and see where that gets you.

 

[PaulMason]

Sounds like you may have a few things going on which can make fault finding interesting. As with most things just try to clear one thing up at a time and see where that gets you.

To be honest, I knew fine well buying a cheap S Class was always going to come with some challenges and ongoing quibbles. But, driven about 100 miles today and it's just super fab to drive and be so cosseted. There is no other way o could get so much car for so little money, so a few foibles can be forgiven.

 

[AndrewOl]

I did the same with a 2006 GL420. It was a lovely thing and I didn’t mind putting some money into it to sort it out and keep it going. Still miss it a bit now but I have a little A207 E350 diesel to keep me busy these days!

 

[PaulMason]

My car did it's thing again today, so as soon as I stopped I plugged the icarsoft in and got th following code..."check component Y27/9 (left EGR positioner). Positioner signs fault". Does anyone know what that means? Thanks in advance

 

[phobos]

Does the car do a kangoroo when you press the accelarator fully to the floor? If so most likely, as mentioned here the turbo actuator needs to be looked at. Had a similiar isue on a older OM642 and there were no codes on STAR

 

[PaulMason]

Does the car do a kangoroo when you press the accelarator fully to the floor? If so most likely, as mentioned here the turbo actuator needs to be looked at. Had a similiar isue on a older OM642 and there were no codes on STAR

Not particularly that I have noticed. Depends on how much you mean by kangaroo, there is an occasional sensation of acceleration being a little surgy if that makes sense, acceleration, slight drop and then goes again, but not an on/off frequent stutter like I would associate with kangarooing