'97 E420, 97k miles, approx. 2 weeks ago suddenly displayed an episode of poor driveability accompanied by a flashing ASR light and a "Check Engine Electronics" warning. Restarting the vehicle resulted in a return to normal driveability and no warning lights (including CE). Inspection revealed no stored or pending fault codes.

Now, immediately upon startup, ASR and "Check Engine Electronics" warnings have returned and vehicle is essentially undriveable, despite multiple restarts. Haven't had a chance to check fault codes yet.

Is this symptomatic of a throttle actuator (motor) failure?

It is, but there should be a stored fault code. The weird thing it did first, which left no fault code, makes me think more along the lines of the EA control module.
With the problem you're having now, would you say it acts like the throttle is almost dead and HARD to push down? Or is it actually running rough or some other type of concern?

Gilly

__________________
Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)

The accelerator pedal moves as normal... no added resistance is felt as the pedal is depressed. Absent is the linear engine response when the pedal is depressed: the engine now just bucks and stumbles when the pedal is moved.

With no pedal engaged the idle speed is stable, although the idle speed was higher than normal following a cold startup... it required higher than normal brake effort to keep the car from moving when shifted into Drive.

Anyone?

The fact that it runs well at idle kinda makes me think it is not a throttle actuator.

Other than not openning, the throttle actuator shouldn't cause a car to misfire.

I had a S500 that wouldn't drive off at times and would set the ASR light that turned out to be an overcharging alternator.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Had a similar problem with my '97 E420, typically on cold days/ early mornings or after having left the car for a while with interior lights on. The root of the problem was too low battery voltage, - add'l charging didn't help either, - one cell was bad. This was still the original battery from october '96. After replacing the battery everything was fine and have been so for three months...Winter comes earlier here in Norway!

Today I have a 96 S320 with ASR and it won't rev at all. When the car is first started there is no light and there is a noise under the hood that sounds like the water pump coming through the radiator. Slight actuation of the throttle turns on the light and stops the noise. Fault codes in 5 systems for EA actuator.

Definitely an actuator. The car CAN NOT be driven at all. It will only idle (does fine idling). When I gave my first reply I interpreted that the car ran bad when trying to drive, but did drive. This car won't rev at all and won't pull the grade into the shop.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Well, its not be driven for a week and its no longer idling well.

From cold startup, the engine now idles with excessive vibration and rhythmically fluctuates between 1000 & 1200 rpm. In addition, the instrument cluster now posts the warning "ACC.SKID CONTROL". Vehicle cannot be driven.

Will pull the fault codes as soon as possible.


Actuator for this vehicle lists for close to $1K!

By "rhythmically" you mean this:

"vrmvrmvrmvrmvrmvrmvrm", right?

Throttle actuator, baby.



uh-huh. Maybe used? Try Potomac German Auto (?) .
Potomac Pat or Pete is a member here from this company, highly regarded in used parts, unsure what type of guarnatee you'd have. Be sure to get a couple gaskets for the actuator to manifold.

Gilly

__________________
Click here to see the items I have up for auction at EBay

Click here to see a photo album of my '62 Sprite Project Moneypit (Now Sold)

You got it, Gilly.

Its "vrmvrmvrming"!


Thanks for the help guys.

Pulled fault codes:

P0507 - Idle control system -RPM higher than expected

P1580


And then replaced actuator... which solved the problem.


BTW, removing the air intake duct and peering directly into the throat of the actuator revealed that the actuator's butterfly plate was open approx. 45 deg., instead of being closed - a clear indication that the problem was actuator-related.

Inspection of the failed unit following its removal revealed that the butterfly plate was no longer operating smoothly through its arc of travel and was failing to return to its baseline idle position.... a crunchy, jerky sensation could be felt when manually cycling the plate. The difference was obvious when compared to the new actuator.