E63 5.5TT - light throttle surging

[AlexM]

Hi there,

I've noticed that my 5.5TT has a mild to moderate tendancy to surging when on a constant throttle between about 1600 - 1800rpm. It makes the car feel jerkier and less refined than I'd like.

I also noticed that on at least one occasion swapping from Shell to Tesco Momentum made it more noticeable, but can't say whether that is the case all of the time.

A quick google suggests myriad reasons that this could happen, but I want to know if anyone else has experienced thi and had it resolved? I have an extended warranty for my car but I don't want to pay a diagnostic fee and have the car back with no fault found. I've done a quick OBD2 fault code scan via the Torque app and it was error-free.

Any ideas?

Alex

 

[BaldGuy]

I get this too on my 63.... I'm going to get Ollie at PCS to check it for piece of mind....

 

[developer]

Me too.

 

[bluestreak]

my car can be jerky because of lead foot on the throttle, managing throttle better solves the problem

 

[JDL60]

Mine does the same, just thought it was a model characteristic

 

[Vilus]

It could be due to the engine management switching from closed loop to open loop map settings. Under light loads the engine mangement system uses the O2 sensors to reduce emissions and improve fuel consumption. Once the engine load/revs hit a certain point the engine operates in open loop which allows the engine to suck up all the fuel and air it needs. With a forced induction engine the switch would be more noticeable as the boost kicks in and the fuel requirement increases. The switching point from light throttle to where the turbo boost kicks in I imagine would be around 1600-1800 revs, and if the EMS can't decide on open or closed loop then the hesitation might create a momentary over/under fueling issue causing a surge/hesitation.

 

[whitenemesis]

My CLS55 did the same and the above explanation concurs with the reason given to me by various people.

 

[Vilus]

On the 55 Kompressor engine it is very noticeable as open loop engages the electric clutch on the supercharger. I always used to drop a gear when giving it the beans from a gentle cruise to avoid the little hiccups around 1600-1800 revs.

 

[abar121]

It could be due to the engine management switching from closed loop to open loop map settings. Under light loads the engine mangement system uses the O2 sensors to reduce emissions and improve fuel consumption. Once the engine load/revs hit a certain point the engine operates in open loop which allows the engine to suck up all the fuel and air it needs. With a forced induction engine the switch would be more noticeable as the boost kicks in and the fuel requirement increases. The switching point from light throttle to where the turbo boost kicks in I imagine would be around 1600-1800 revs, and if the EMS can't decide on open or closed loop then the hesitation might create a momentary over/under fueling issue causing a surge/hesitation.

This. It happens a lot on motorcycles too.

 

[AlexM]

Hmm... that's a bit disappointing if it is thought to be characteristic.

I thought that euro 6 engines are always under closed loop fuelling control as they used a wideband lambda sensor - the lambda target is just richer under acceleration, and the ECU uses manifold pressure to adjust the lambda targets and correction values. My older turbo cars did go open loop because they only had a narrow band lamda sensor, whereas the M157 has 2x wideband lamda pre cat and two narrow post-cat.

It really feels as thought the engine is mapped to be too lean at that rpm / throttle. When I've mapped programmable ECUs in the past this kind of feel is always solved by adding a touch more fuel or tweaking the lambda target to be slightly richer.

I've also noticed that sometimes the idle speed can get itself into a mess when the engine is still in cold start and you select forward from reverse or vice versa. I don't think the same control system works of idle, so probably conincidence.

Has anyone actually had this investigated via Star to look at lamda compensation or something else? was it ever resolved, or even improved?. really interested to get some info before it goes back to MB for investigation.

Regards,
Alex

 

[JDL60]

Did you ever get this checked Alex?

 

[JimmyR]

Don't shoot me down if I have got this wrong but doesn't this motor have cylinder deactivation, in C mode at least? That cutting in and out on light throttle would more than likely be causing what you are describing.

 

[daveenty]

Nope, as far as I know cylinder deactivation was only brought in with the W213 model.

 

[JDL60]

As above, just in the 213, that wasn't present in the 212

 

[AlexM]

Did you ever get this checked Alex?

Not for the moment. It is a nuisance TBH, but I'm going to add it to the list of issues for the next service.

The stumbling feels exactly as it did when I was mapping my old car and you were running it leaner than it wanted to run - when running around 14.7:1, you tend to get more stumbles and surging at light throttle. Given the engine is running closed loop and can monitor it's combustion on a cylinder by cylinder basis, you would think that it was almost impossible for a mixture or ignition issue to manifest without triggering a CEL.

I'll update when I've had the car looked at, although I suspect that I'm going to get a 'they all do that sir' response.

Regards,
Alex

 

[JDL60]

Not for the moment. It is a nuisance TBH, but I'm going to add it to the list of issues for the next service.

The stumbling feels exactly as it did when I was mapping my old car and you were running it leaner than it wanted to run - when running around 14.7:1, you tend to get more stumbles and surging at light throttle. Given the engine is running closed loop and can monitor it's combustion on a cylinder by cylinder basis, you would think that it was almost impossible for a mixture or ignition issue to manifest without triggering a CEL.

I'll update when I've had the car looked at, although I suspect that I'm going to get a 'they all do that sir' response.

Regards,
Alex

Thanks Alex, I suspect so too. Sounds like yours is more pronounced than mine

 

[Steveml63]

Hi,
When we first got our 2015 ML63 AMG (with the optional increased HP -Performance Pack) - I had some near misses at roundabouts.
You would coast to a near halt approaching a roundabout and then, if clear, plant the throttle to pull away. Result - nothing! for what seemed ages but was probably less than a second. Then the engine would react and off you went.
It seems to be heavily related to engine mode - Comfort or Sport and whether Traction control is on or off.
The problem nearly disappears if car is in Sport mode with Traction switched off.
Cheers
Steve

 

[Gastro]

Oh dear. This is really sterilising my idea of getting an e63 S
Think I'll be getting an M5 after all...

 

[Luke-BITURBO]

Haven't noticed any issue with mine

 

[Peter DLM]

Never had any problems with mine either.