So on my way back from the dealer, I had this happen.

Youtube vid is uploading. Sorry for the profanity.
(go to 1:00)

Note how the car suddenly lurches (you can see the hood starting to point upwards). I was barely touching the throttle. I honestly thought someone had rear ended me, but nope.

Really odd. I was driving in C (normally, I use S) so I am hoping its one of those random transmission idiocy moments where it downshifts all of a sudden, but even so it seems like too big of a surge in power... albeit only for a moment.

I will try that transmission reset procedure tonight...but man this is scary.

 

Looks like an odd transmission shift to me. Have you had the TCU software upgraded by the dealer? Mine was like a totally new car with the latest (well, December 2011) code.

 

Wasn't anything on the work order about TCU reflash. They did do a recall for the camshaft position sensor or something, wiring harness related.

I did the reset procedure and blasted around for a bit. Hope its gone. But can't confirm its gone...

 

Haha @ Yonge and Steeles. If your car is black... I may have seen your car a few times (our cars are rare) anyways not to scare u but that's what happened b4 my tranny blew :/ I have a thread on that. That thund happened to me as I was making a left turn scary **** but Luckily it continued to move :/ or else I would have gotten hit. It blew like a day after so... Yeah... Get that **** checked out ASAP

 

You might want to talk to your dealer about getting the latest TCU code. The early 7GTRONIC transmissions had a lot of complains about odd and rough shifting. Over the years, they have tweaked the software and smoothed things out. One thing they did was to prevent an automatic downshift to 1st gear until the car is completely stopped. This prevents that sort of rev-jerk that you'd sometimes get when slowing at just the "wrong" pace. It also evens out all of the shifts. Most dealers will charge about $100-$150 for this and it's well worth it.

 

Hm. It happened again, twice, on the way home. Both times I was stopped and had my foot on the brake, and the car just randomly revved. Very disappointing.

The idle speed also seems to be a bit up and down (but within maybe a 150 RPM band...hard to tell). I did have the AC on though.

Two other things.

1. Its been really windy lately, and while it surely might just be my brain, I can't help but wonder if the RPM bursts are correlated to wind gusts (O2 sensor?)

2. This only started when the dealer performed a recall related to "retrofit adapter wiring harness on camshaft adjustment solenoids"

Part # is 271 150 01 56 05


Something is up for sure, though.

 

Siyan I have had the exact same proplem. Sometime it does it sometimes it does not seems like lately it been more and more it only happens when i come to a complete stop and I am at idle. I am going to take it in and get the latest flash like Rodney says will let you know what happens..

 

I used to have the same/similiar problem with the engine rev going up when at a stop. I have a Kleeman programmed ECU and had to get it reprogrammed. The TCU was done as part of the performance centers process. I have not had the problem since.

I do occasionally get the hard downshift to 1st when moving at that "magical pace" that Rodney refers to. But yours seemed to be on accelerating slowly. It also seemed more harsh than what I have experienced.

 

Thanks Fatz I also have the Kleeman programmed ECU and I get a hard burst and then stops wont do it all the time. So maybe thats the proplem goona drop Cory a email and see what he has to say. Mine does not happen very often but it seems like more and more lately.

 

This was happening to me and I had my valve body replaced by the dealership and it solved the problem. Could be a possibility.



Angelo

 

Yes get your camshaft position sensor replaced if that don't help get valve body replaced, i was in stop and go traffic in heat and the car would just surge forward i almost hit a few cars.

 

My 05 S430 4matic periodically has a momentary acceleration when driving at slow speed and I hit a bump. It doesn't happen everytime I hit a bump but occasionally. The acceleration is not dramatic but certainly noticable. Further, the acceleration only lasts for a second and then resumes normal speed. Also note that this can also occur when my foot is completely off the pedal (coasting). There are no dashboard error messages resulting from this condition and I have not taken it to the stealership for diagnosis as this is not severe or urgent. Is this likely the pedal module or other lose connection someone has experience with? Feedback is appreciated!

 

ketoj, I would suspect something loose in the pedal or the throttle body (maybe even a vacuum hose) might cause this.

 

Thanks Rudeney, guess I can randomly wiggle and poke around under the hood with engine at idle and see if i can cause that momentary acceleration. I suspect even a lose connction at the mass air flow meter could cause this.... trial and error is probably the best approach, thanks.

 

Update? Happening to me too. Only at a complete stop.

 

Went away on its own, actually.

I since sold the car. Needed 4 doors as we have family plans. Really miss the CLK despite its "oddities".

 

Seems too go away on its own for now, haven't replicate the problem :/ I'm hoping its a morning thing