Loss of power at 1900 revs. Uneven at idle

[Steve Delves]

Hi Everyone.

My 500E is suddenly loosing power at the same part of the rev range (1900revs) in all gears. It is also uneven at idle as well. Also when engine is warm and you are slowing from 20kmh to a stop the revs will jump up and down.
I've had the ETA, Mass airflow sensor checked. The spark plugs have been checked and cleaned. the rotors have also been checked and cleaned and the wires and plugs to the sparkplugs have been checked along with the battery connections.
Any advice would be appreciated guys..

Steve

 

[gsxr]

First thing I would do is check for vacuum leaks, with a smoke machine connected to the intake manifold.

If there are no misfires, it's extremely unlikely to be related to secondary ignition (caps/rotors/wires/plugs/etc). It's probably mixture or throttle control.

Are there fault codes on any module, that keep recurring after they are cleared? And is this a USA-spec car with DM+CEL?

 

[breizh500]

Hello, When I spend a speed, the slowed is weak or the engine stops, and then it is difficult to ride it on the bridge! And the pedal race seems long to get the engine up! For info, all the electric system is new, except high voltage cables!

Thank you for your help, Franck

sorry for electronic translation!

 

[gsxr]

If accelerator pedal travel is excessive / long before the engine responds, you may be in "limp mode".

 

[breizh500]

For information, the ABS light is on, also know that I could not purge the ABS box, only purge all four wheels! what do you think when indicating the " limp mode"?

 

[gsxr]

For information, the ABS light is on, also know that I could not purge the ABS box, only purge all four wheels! what do you think when indicating the " limp mode"?

You will need to pull fault codes from the ASR module to start with:

De-Coding

Information pertaining to diagnostic codes, how to obtain and dechiper them, and how to remedy them.

www.500eboard.co

 

[breizh500]

You will need to pull fault codes from the ASR module to start with:

De-Coding

Information pertaining to diagnostic codes, how to obtain and dechiper them, and how to remedy them.

www.500eboard.co

after checking the codes, no defects, see photo!

 

[gsxr]

If the ABS (or ASR) lights are on, there should be SOME fault code stored. If there are no codes, the blink code reader would show 1 blink.

Wouldn't hurt to check all fuses, including the blade fuses located on the GM/BM (power supply module) inside the CAN box.

 

[breizh500]

After checking all the fuses, everything is ok!

 

[breizh500]

Therefore the ABS light is always on! would it have something to do with limp mode?

 

[gsxr]

Does the ABS light remain on after starting the engine, but before the car moves?

I would also pull the instrument cluster and verify the bulbs are in the correct positions (2, 3, 4, 5, etc).

 

[JC220]

Does the ABS light remain on after starting the engine, but before the car moves?

I would also pull the instrument cluster and verify the bulbs are in the correct positions (2, 3, 4, 5, etc).

View attachment 139854

Great suggestion Dave - had this on my 500E before! They can easily be mixed up by someone else and a bulb out warning for example could show as ASR etc instead.

The wires have labels like Dave's pic and additionally the numbers are stamped beside the 'oles in the metal cluster panel. Make sure the numbers all match up.

If you don't have cluster hooks reach up from below and push the cluster out. Easier to buy the cluster hooks from dealer or ebay.

 

[breizh500]

The light is on as soon as I turn the key power supply, it remains on when the engine is in operation! Is my ABS lamp problem related to limp mode? I will check what you advise me! is it possible to find the electric brake system! Thank you

 

[gsxr]

The light is on as soon as I turn the key power supply, it remains on when the engine is in operation! Is my ABS lamp problem related to limp mode? I will check what you advise me! is it possible to find the electric brake system! Thank you

First verify the bulbs are in the correct position as shown in post #11 above. It would be very odd to have the ABS light on, and no fault codes present for the ASR module (ASR module does both ASR and ABS).

Not sure what you mean about "electric brake system"...?

 

[breizh500]

"electric brake system"...I am looking for electrical and hydraulic diagrams for ABS ASR !

 

[gsxr]

Factory service manual is at the link below. Schematics are in Group 24, other info is in 30, 42, and 43:

Mercedes Benz Model 124 - M119 Maintenance Manuals

 

[breizh500]

Thank you very much for your speed and time!