FiftySquid

I'm sure that you guys get really vague troubleshooting questions all the time. Let's turn it into a game!

I don't think I have nearly enough information for anyone to actually solve this mystery but it's in the shop and they'll let me know in a few hours.

Specs:
2003 E500 Sport
36K miles
No after-market anything and no major problems - ever.

Symptoms:
While driving I suddenly lose power. The accelerator does nothing - even when pressed all the way to the floor. After "rebooting" the car (shutting it off for 10 seconds and starting it up again) it runs fine.

The first time it happened after three minutes of driving. The second and third times it happened after 10 minutes of driving. All three instances happened after taking off normally from a dead stop (i.e. I was driving and stopped at a stop sign). when it happens I start accelerating normally for about 30 feet and then the accelerator cuts out.

The check engine light only came on after the third instance and I went straight to the dealership.

Let's see who can guess closest to the mark! First prize is... bragging rights, I guess.

Edit:
I know nothing about cars so I'm going with... fuel pump?

Racin_fool

I would guess the front Sam or the EIS.. Doesn't sound like a Crankshaft position sensor because usually when those fail you wouldn't be able to start the car again for like 20 minutes.

FiftySquid

Okay this is odd. I heard from the tech and he said there were two codes:
Trasmission Control System (I think)
and
Accelerator Position Sensor.

Okay so what needs to be replaced? He says nothing! He says it's fine and they couldn't find anything wrong. Everything checks out!

How is this possible?

Racin_fool

replace the accelerator pedal. It has two potentiometers in it and it sounds like one went out.

It's not the first one I have seen go bad. Most of the time this happens on W220 cars though.

Also, about the TCU code, there may be something wrong inside the transmission control module. The check engine light will come on if it has a fault code in the transmission control module.

FiftySquid

Yep - it happened again and I took it in again. They want to replace the Accelerator Pedal Sensor and quoted me $533 (installed). Does that sound right?

whoover

Where do you live? In CA, MA, ME or VT it's covered by the extended emission control warranty for 7 years / 70K miles. I had mine done under extended warranty (on a 220) but assumed it was a cheaper repair. Installation is just a few minutes. Clearing the codes is the longest part. Did they charge you to diagnose that nothing was wrong?

whoover

The TCU code is probably a phantom. It will throw an "implausible speed" code if it's getting inconsistent signals for MPH, RPM and throttle. For instance, when floored the transmission is told "it's floored -- downshift dammit" but the engine is idling. The failure rate of the pedal sensors is outrageous.

Racin_fool

takes 10 minutes and only 3 tools..

need a 10mm or 13mm socket and ratchet and a small screwdriver.

take out the floormat, get a flashlight if needed. there will be a small black cap behind the pedal, pry it off. Use the socket and ratchet to unbolt the pedal assembly. Next unplug it and plug in the new assembly and bolt it back down. Thats it..