I have a 93 240 with approx 180k miles on it. My son was driving on the highway, heard a sound similar to the starter disengaging, and the car died suddenly. I had it towed to the dealer, assuming timing belt, since the engine has spark and fuel. Diagnosis was speed sensor and damaged flex plate. They bent the flex plate back and replaced the sensor, but the car misses on acceleration. I replaced the wires (some were in bad shape) , but dealer insists that the flex plate will cause this performance. I, m not about to lay out $400 for the part plus 5 hrs install until I have ruled everything out. Anyone know whether a slight bend in the flexplate could cause the motor to miss on acceleration?
Thanks

This begs a few questions. How the heck did the flex plate "bend" in the first place? And did they say the bent flex plate was the reason for the faulty speed sensor, because it's pretty hard for it to contact the sensor unless the flex plate went oval. And bending the flex plate back is a hack.

Anyway, if the sensor/flex plate scenerio were true, I suspect the engine would miss all the time, not just under acceleration, since the sensor is not load-dependent. You could argue that under load the flex plate might distort under loads, exaggerating the misalignment with the sensor, but that is starting to sound a little farfetched.

Your thoughts make sense to me, The tech claims that a rock or other foreign object must have entered the housing and caused this damage . The torque converter housing covers were missing, and I was able to view the "bend"- it looks like the edge of the ring has a slight bend. Bear in mind, the car would not start until he replaced the speed sensor. If you are not familiar with the flexplate, take a flywheel and weld a 1/2" ring of 12 gauge metal on edge just inside the teeth. The ring has square holes cut out which the speed sensor "reads". The Dealer tech described it as functioning almost like a stereo turntable with a strobe light to adjust the speed. My thinking is , why does it idle and cruise smoothly? The misses are only during acceleration. My plan is to re-check fuel delivery, replace cap and rotor and recheck wiring to the injectors and emission sensors. Do you think vacuum could be a suspect here?

It certainly sounds likely that if the speed sensor can't properly read engine speed that it could cause the miss. If you do change the flexplate defintely change the rear main seal while in there. I have a spare flex plate if you do end up needing one. just email me at aas62@yahoo.com.
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1990 240 Sdn 277K,tach,strut brace,turbo sway 1990 240 Wgn M47II 157K,tach,strut brace,poly bushings,IPD sways,bilsteins

Please, what is a flex plate?

Its similar to a flywheel, bolts onto the back of the driveshaft and connects to the torque converter in the tranny. The starter gear teeth engage in the extruded edge of the flexplate to crank the motor when you turn the key.

Thanks. I'm curious why it's a flex plate and not a flywheel..
Anyway, now I know what you're talking about.