500E stumble
 

While I know others have experienced a low speed and/or idle /or turning stumble, My 92 500E occasionally experiences a severe stumble/power loss and sets off the check engine light.
The stumble I describe is like an old 440 Magnum with the valves floating out...resulting in a puffing sound and a considerable loss of power. Turning the car off and waiting a few minutes usually cures the problem. Yesterday during a 3 hour trip it actually came and then went away for no apparent reason.


While there may be multiple issues involved in the Fault codes,
the Fault codes are as follows:

5/02 (check engine light came on, car runs fine)

-Crankshaft position sensor
open or short circuit (ACTIVE fault)
-Rt Upshift delay switchover valve
open or short circuit (stored fault)
(we have plugged the vacuum line to the bowden cable
in a diagnostic effort to see if the bowden cable is
indeed bad) (is this an effective diagnostic attempt?)
RESET AND LIGHT STAYED OFF, RUNS FINE

CONCLUSION IS BOWDEN CABLE BAD, TO BE REPLACED
DURING NEXT OPPORTUNITY, BUT WITH THE PLUGGED
VACUUM LINE, SHOULD NOT BE AN ISSUE FOR NOW.
SIMPLY KEEPS CAR IN LOW GEAR LONGER DURING WARMUP?

8/6/02 (check engine light came on, engine stumbles @all rpms)
-Crankshaft position sensor L-5
open or short circuit (ACTIVE fault)
-Rt Upshift delay switchover valve
open or short circuit (stored fault)
-Closed Throttle Position Switch (stored fault)
-Rt Ignition System Defective (stored fault)
RESET AND LIGHT STAYED OFF, RUNS FINE

9/30/02 (check engine light came on, engine stumbles @all rpms)
-Crankshaft position sensor
open or short circuit (ACTIVE fault)
-Rt Upshift delay switchover valve
open or short circuit (stored fault)
-Rt Ignition System Defective (stored fault)
RESET AND LIGHT STAYED OFF, RUNS FINE

UPON REPAIR OF THE POWERSTEERING PUMP, I NOTED THAT
THE DISTRIBUTOR CAP AND ROTOR SHOWED CONSIDERABLE, AND I REPEAT CONSIDERABLE WEAR IN LIGHT OF THE FACT I REPLACED THEM BOTH LESS THAN 10,000 MILES AGO.

ANY SUGGESTIONS????

Sounds like the ignition module(EZL) has a problem! Not un-common at all on the M119 engines. There are 2 coils & sometimes the ignition system on these cars don't send dwell signal to one of the coils.

The reason that you always get the crank sensor code: the engine MUST be running when the codes are being read from the ignition system.

MB Doc/All,

Can't failing coils cause burned-up caps & rotors? Fer sure that's what happened with my 300TE (diff engine, etc. but same symptoms as relates to the ignition parts)

Is there some way to diagnos which is the culprit.

The EZL module lists for some $2,500
The coils are only $165 each

While cost is somewhat less, its still tough.

Should I simply try one coil, then the other, then the EZL?

Someone posed the concern that if 1 coil goes bad, it can affect/damage the EZL...and or the other coil??? Is this possible.

With an interrmittent problem such as this, I suspect it make take time to determine if the problem is solved.

LAST BUT NOT LEAST...AND I KNOW THIS IS ONLY A GUESS...
I am going on a road trip this weekend entailing some 900 miles. Should I leave the 500E at home? I.e. will it get progressively worse (occur more often) or will it more likely just fail catastrophically? I can simply buy a coil and carry it with me if I can isolate for certain that the coil is it, but otherwise that only covers 1 of the three candidates.