Strange accelerator issue pulling into driveways (Update)
 

A couple weeks ago I experienced a strange situation pulling into a drive way. As I pulled into the driveway - you have to cross over the side walk and up a steep short ramp (common style drive way)

Even know my foot was not on the g@s pedal the car would accelerate. It wasn't a consistent thing, so I just assumed that it was sticky throttle linkage and made a mental note to lube those parts in there good. I assumed it was happening more because I was depressing the g@s pedal the cable or linkage was sticking.

Well today I noticed it but it happened when my foot was no where near the g@s pedal. I was just pulling into the driveway at work and it started to accelerate. When I turned and pulled into a parking spot and hit the brake the engine felt like it was revving just a little bit. I hit the brake several times and noticed it, and then it went back to normal.

Any one experienced this before?

Tried to do a search on this one - but I am stuck on search terms and getting either way to many results or too few...

Any help or links is appreciated.

-Scott

Bad motor mounts. Slow down until you can fix it.

Bad engine mounts?

Interesting because it doesn't vibrate a lot but, that makes total sense. Is that a do it yerselfer job for the technically challenged like myself?

Man, it will be nice once all these worn out parts are replaced. ;)

Thank you - I appreciate the info.

just ordered my replacement motor mounts. Thanks again for the help!

The engine mounts came and I did not inspect them close enough.

When I was about mid-way through removing the old ones (which weren’t too bad at all in firmness and general appearance) I realized that one of the engine mounts that they sent me was the wrong part. It looks like it was bagged wrong from their supplier as all the numbers on the bag were identical to the correct one.

Now like I mentioned the old engine mounts were in good shape. I would guess a few years old at that. The rubber was solid and firm so I reused one of them… the best looking one with the most height and firmness and replaced the other with the correct new one. I also replaced the transition mount as well. (What a funny item that is. The logic of exactly how the transmission mount works defies me. I got it in though.)

The bad news is that the problem is still present.

When I give the engine the violent shake test it seems pretty darn firm.

I am at a loss here as I can not figure out why this is still happening. If the old mounts were in any worse shape I would blame the old mount – but at the same time with out having two perfectly new mounts I can’t rule it out either.

Has any one experienced a similar problem that didn’t turn out to be the engine mounts?


At least I learned that I could do the job and how to do it. I also learned the ‘inspect mail order parts before starting the job lesson’ in a big way

you are certain the bolts up under the mounts are BOTH there? is the transmission mount intact or seperated.....It really has to be one of those.

Both of the bolts are in there – I put them in myself the other night and I don’t think they are going anywhere as I tightened them pretty good. I replaced the transmission mount too. The old one was in pretty shoddy condition but the new one while not seeming like the most rugged piece of rubber in the world was intact when I installed it. I installed it the same way the old one was installed – which I am assuming is correct as I have not had any transmission problems to speak of…. Well, that isn’t entirely true, last night when I was backing up – I heard some strange sounds coming from under the car, but I attributed that to big load in the trunk because after I unloaded the Costco load and moved it the sound was gone. (I need shocks or springs in the back in a big way)

I am at a loss at this. When the other new mount comes in I will be under there again, and will see if anything ‘looks’ off.

One thing I should mention is that I realized that the accelerating doesn’t just happen on inclines but it seems that it has a lot more to do with the wheel being turned almost all the way in either direction like turning into a parking spot.

The engine will rev up and it seems that if I tap the brake once or twice it settles back down…

maybe you have too little slack in the accelerator linkage and body flex is enough to pull the linkage.....it can't be anything lese....something is moving and pulling that linkage....

unintended acceleration
 

you sure this car is not an old audi? just kidding.

i would be very surprised if it is body flex. the unreplaced motor mount might be failing in tension. if you jack up the motor does it lift off the mount that you didnt replace?

lmao - audi 5G baby

i called mercedes source today and they are sending the correct mount for me. i hope this does it.

hopefully the part will arrive berfore the weekend and i'll be able to use my friends garage again. that will likely be the next time i jack up the engine.

it is strange though because i feel more vibration now than before... i know i am due for new fuel filters, and maybe i am just paranoid. at least the reving issue is not as bad as before the change - so i will keep my fingers crossed that the other 33.3% of the job will fix it.

i'll report back