CLIFF4781

Occasonally, I get no response with pressing on the accelerator, then suddenly "peals rubber". Then there will be no problem for several days and the hesitation repeats again. Seems worse in parking when you suddenly take foot off pedal and then apply pressure again. Dealer hasn't found problem. Any suggestions?

trumpet1

Many of the acceleration and transmission issues can be resolved by getting your car out on an open stretch of highway at a time when their is no traffic and just floor the car from a standstill and open it up as fast as you can accelerate. This resets the tranny module. Do this 3 or 4 times and see if it behaves better. Many new cars need a good workout to train the module to adapt quicker to various styles of driving. It has worked for me in the past. Once about every 3 months, I'll do this.

CLIFF4781

Taking my car back for service today. The same old problem of hesitation. Acceleration didn't help

trumpet1

Hopefully you just need an ECU adjustment.

LAZARU5

I have a new friend that has this exact same problem with his 2007 S550. We would appreciate knowing if you were able to resolve the problem.

NJS430

If you are on a grade when it happens it may be that the "Hill Holder" feature has locked the brakes on. I believe the 2009's have the Brake Hold feature that would lock the brakes on if you pump the pedal after coming to a complete stop even if you are not on a hill.

Carcrazy1

I thionk the vehicle needs a long drive so that the new parts are worn out a bit and every thing comes in place.

new550

Cliff4781 - Please do post the results of your service visit...I have the same intermittent issue with acceleration on my 07 s550v4 ! I find its worse in "sport mode" than "comfort mode", but happens in both.

new550

Cliff4781 - Did you ever solve the issue, I have had my s550v4 in to service twice for this hesitation...no improvement with updating engine and transmission...what was your end solution?

Thanks in advance,

CLIFF4781

I did get the hesitation problem resolved. As I understood it, they reset an electronic device and presto no more problems. It has been so long ago I don't remember exactly how they did that. Hope that may help you.

trumpet1

Sounds like they flashed your engine and transmission modules.

itschase

Most drive-by-wire cars have the same adaptive reset process. It does not matter if you have Keyless-Go or not, get your car to the ON mode with the engine off. You want the system check lights to be on the dash. Hold the accelerator to the floor, past the kick-down stage (where you feel a slight hesitation and then it gives) for approximately 30 seconds. This process is supposed to bring the adaptive transmission ECU back to factory settings. What is happening with the hesitation is the torque converter is not locking up all the way because it is preparing for a rapid changing of gears. This comes from frequent spirited driving, and is emphasized by the fact that the (non-AMG) car has 7 gears to chose from. It will often wait to see how far you depress the accelerator to determine how many gears to downshift. There is a product called a 'SprintBooster' that is designed to help this issue. One disadvantage we face is that when we depress the accelerator we simply move a module that sends a signal to the ECU, is calculated and sent to a servo that controls the throttle valve and fuel output. The sprintbooster increases the signal output from the accelerator module and allows the vehicle to process input faster. It is said to all but eliminate accelerator lag in most drive-by-wire vehicles, and under most driving conditions. It is a very popular add-on in the BMW world.

buildstrong

I somehow think you may need an ECU adjustment. However it may be a good idea to get your car on a open stretch of highway and check out for yourself first.

new550

itschase - thanks..your explanation fits what I see...approx 1/2 to 3/4 throttle and the car thinks for a second before it decides to go...the delay in torque converter locking up would explain it, but seems like a setting in the engine or tranny should also accomplish what the "sprintbooster" would do? I have had mine to the dealer 3 times to try to eliminate the delay, but no joy...just new ecu and tranny software...anyone else see this delay ....try steady speed at 35-45 mph, go 3/4 down on gas and there is about a 1 second delay before the car starts to pull...repeatable in my case...

AMG1

Though I've never experienced that problem with my S, I would have to think its the driver adaptable transmission. I'd open it up more often, blow the cob webs out of that V8 and enjoy all 382 of those ponies. Hope this helps.

nitinopp

If you ever need someone to watch your Carrera GT while you're out of town just give me a call.

AMG1

haha my housekeeper Mary typically looks over my rides while Im out of town however I'll give it some thought.

AMG1

G-Unit16

This sound like something I've been experiencing in my 2016 G550n periodically for the past few years. It's been in the shop with two different Mercedes dealers about 5 or 6 times for the issue and no resolution. We've done all the usual suspects, batteries (yes both), oxygen sensors, plugs, transmission service, air & fuel filters, etc. I'd like to describe my issue a little and see if you think your prior assessment applies. It only occurs the first first drive of the day and usually only after the car has sit undriven for several days. After coming back from vacation or even just 2 or 3 days on non use, when I would accelerate the vehicle will lose power and sometimes stutter and the whole car will shake violently until you take your foot of the gas and then it seems to reset itself and you can accelerate normally. I have always suspected it's an issue with the transmission searching for a gear and not finding it. One time the traction control light came on, although the pavement was as dry as could be and I was on flat level ground. But the effect is the same, power is being cut to the wheels and you cannot "push" through it so to speak. I have tries many different things, including pressing the pedal to the floor when this happens, and there is no effect. The only resolution is to take foot off and then you can immediately depress again and move one. I know know how the fact the vehicle sits for a while effects this. This issue has happened probably 15 times in 3 years and only once when it had been driven in recent days so it truly is almost solely after sitting a few days. And it has never once happened after the first ride of the day. Doesn't matter how short the ride is, could be 5 minutes. The rest of the day, multiple starts & stops, no problem. Sorry for such a long post but you are the first person that seems to maybe have a solution and I will OWE YOU BIG TIME if you can help!!!

John Sunderland

Hi G Unit 16,
The problem with the with hesitation and lumpy first gear engagement in my 2017 SLC was resolved after a MB independent specialist discovered that the sump had a hair-line crack and was leaking gearbox oil. Level of oil may have been depleted. Manufacturing defect diagnosed and accepted by the main dealer and corrected free of charge.
John Smith