Peter Kanyike

When I'm driving my SL 500 R230 suddenly my acceleration fails while in drive gear but keeps raving but doesn't respond until I stop put it in parking then drive again then it will move anyone has any knowledge what could be the cause?

Tokyoite

automatic or manual mode?

Peter Kanyike

automatic mode

tonylinc

Is the transmission slipping?

Peter Kanyike

its doesn't seem to be slipping

NiceMerc

It has probably gone into 'limp' mode. When it used to happened on my 2004 it was due to a well known problem with the conductor plate in the transmission.

As is often the case with the R230, the starting point is to read the codes with a diagnostic tool such as iCarSoft or something more sophisticated.

Good Luck
Gary

Peter Kanyike

thanks for the feedback

kbob999

Another well known cause for limp mode is the electronic throttle pedal giving errors to the ECU.
If you stab the throttle, and it goes into limp mode, you will likely need to change the throttle pedal to fix it.

If you stop the car, turn it off, then start and drive again, it will go away temporarily. That is until you punch it again.

tonylinc

VERY INTERESTING, my 2008 S550, with the same engine as my R230 SL550, runs excellent, like a new car... has all new spark plugs and I also got all new ignition coils for good luck when I bought the car, along with new motor & tranny mounts, oil change, new filters... Runs great, except one day when I floored the gas pedal. Check engine light came on, and car was running like crap. Drove home, parked, next drive it was fine again except check engine light was still lit. Codes indicated a camshaft position sensor, there are four at front of engine. Replaced those. All fine for weeks until I floored it again to pass someone. Limp mode, loss of power, check engine light. I pulled off the road, shut the engine off, restart, fine again! SO, it appears this car does not like having the pedal put to the floor. My W140 was the same way; ran beautifully but not if you floor it!! My S550 gets 27MPG on a long trip. I thought it had an issue with oil related variable valve timing actuators, but now I think it's caused by the electronic throttle pedal giving errors to the ECU. If you drive normally without flooring the gas pedal, the car is 100% perfect, and the car accelerates very nicely for a large sedan. The S Class is supposed to be more reserved and stately, so in theory you shouldn't have to floor the gas pedal, and so for that kind of driving I bought an SL550, and also have an SL600 (!!!) Which you never need to floor that one, probably never will, that car does 100MPH without any effort!, and a Maserati. Funny, my Maserati owner manual says, in two places, "The car will execute shifts more quickly if requested with the accelerator on the FLOOR and RPM exceeding 5000RPM". So, that is the way they want you to drive that car. Maybe on this S550, I'll look into replacing the electronic throttle pedal; it looks like they are $117 at AutohausAZ.

NiceMerc

Given your stable of cars, you're probably aware, but if you haven't already done so, you might save yourself some time and money by getting the codes pulled before you start replacing parts. iCarSoft or Star or a friendly indie will get you deeper into the systems and should get you closer to the problem. A replacement pedal at $117 plus labor isn't too bad, but in general, throwing parts at a problem with fingers crossed is an expensive way to keep these cars on the road.

My 2004 SL had a strange problem with the cooling system. The AC ran cold and had been checked by my indie already. On long journeys on hot days I had to keep turning the AC up to keep the cabin cool. A quick check with a diagnostic scanner showed that one of the thermistors was open circuit. I got a packet of replacements for just a few dollars and my indie pulled out the overhead console and soldered in the new part. Without the codes - and some help from Rodney - I would likely have gone after the AC control unit and spent a lot of money on replacement parts with little success.

Good Luck
Gary

brucewane

Regarding the accelerator pedal, you might want to check this thread . Basically a ten cent fix, if that.

Seems that the cars want to see 4.8 volts from the pedal for wide open throttle, but if that value is exceeded at all the systems throw the car into limp mode.

I've experienced this with my SL600; I plant to put a thin spacer on the back of my pedal, somewhat like in the thread I linked to.

Mercedes really should have allowed for a little more voltage variation in their coding, since most electronic components drift a little over time. Hell, .1 volts over a 5 volt range is only a 2% variation - for most electronic components, that's within normal for brand new!

tonylinc

Actually I did get codes and that was what told me to get new cam position sensors, they are about $25 each and pretty easy to replace at the front of the motor. But then on a subsequent trip the car did it again, and I knew to pull over, shut off the engine and restart. Kinda takes the wind out of your sails after passing someone, but after restart the car was fine again. Now the new pedal has arrived, it's still in the box, cost $123 including shipping. The car runs so well the only time it has that issue is when you floor the gas pedal. I really don't think it's caused by oil related VVT parts, I mean the engine runs quite beautifully. I'm now believing 100% that it's caused by the throttle position sensor. It's not the most pressing issue but when i have a bit of spare time I'll install the new pedal and gop out looking for someone to pass. LoL We'll see as i am curious now if it corrects the issue!