Hi to everyone dropping in on this thread,

The car involved is 1987 190E 2,3 8 valve (M102), ezl unit, auto tranny

Let's get to the problem itself. My car stumbles, engine dies for milliseconds randomly. As engine stumbles, the rpm-gauge drops. The engine doesn't stall but it "stumbles". It's not a certain rpm reading, it can occur all over the "scale".

I have checked all the ignition cables, rotor and distributor cab (changed to new ones) and run on bosch iridium spark plug. Plugs looks good.

I have been monitoring this problem for some time so this is what I know;

I measured the L5-sensor located next to power steering pump, it's within specs on service manual. No ground leaks to ground. I tried to follow the coax cable and wiggle it when measuring but no difference. I do not have a scope to see the shape of the pulse it generates.

I did also check the cable labeled td-signal from ezl unit to terminal block on diagnose connector and from connector to fuelpump relay/cis-module. With a ohmmeter hooked on the the cable I get no resistance. But when with cables plugged to units and ohmmeter on ground and terminal block at diagnose connector I get 960 ohm. I narrow down the cable with connection to ground to fuel relay/cis unit cable. Is this right? Should there be a leak down to ground? The reading was measured with battery unhooked.

I did also read that ignition modules are usually working or not so I hope mine is still ok. Am I wrong? Could it cause random failures?

I take the dropping rpm-gauge as a hint of what's going on. Tacho is connected at the terminal block on diagnose connector. What could cause the missing td-signal?

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'87 MBenz 190E 2,3 8vlv