1992 300 E 187K + miles. After getting to operating temp or more(80 C) the engine will start to sputter, tach drops out and engine stalls. After cooling down with hood up for a few minutes it will restart, but dies in a few minutes again.

No check engine lite on first test drive.

checked codes. CIS-E MAS code 17 - "O2 sensor signal wire shorted to ground or positive". I cleared that code and it did not reset even after the vehicle stalled several times.

Replaced dist. cap, rotor, wires and plugs as a matter of routine maintenance. I removed the Ignition control (I/C) module and cleaned off the old dielectric heat sink paste and installed a new coat on the bottom of the module and on the fender.

Re checked for code after stalling fit and check engine lite came on.

Code 7- "TNA signal-(rpm signal) at CIS-E control unit N3 implausible".

I dont have MBZ scan tool. The best I can figure is that either the crankshaft position or reference sensor is faulty or the IC(EZL) module is shorting internally from heat. I was starting to suspect the possibilty that the coil was shorting out-before it set this code 7.

Right now I'm am trying to find best prices on used parts for testing or maybe some one "parting out" locally of a 300 E. The module and actually all these parts are damn expensive.

I'm in LA county, CA.

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1982 MBZ 300SD Turbo Diesel- just turned 200,000- just breaking her in

Will the car run with the MAS relay disconnected.
You will need to jump pins #1 & 2 on the connector.

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Haven't tired that - neat trick. I removed the crank sensor and inspected, cleaned it up re installed. I moved the wiring around when checking it but did not really get under the air cleaner to inspect harness good. Maybe it was chaffing and shorting out.

The MAS plastic bracket was broken and held to bracket with tie strap. I cut that and moved relay to check wiring. I just set it aside between the batt. and CIS module for now.

The car has not stalled on a short test drive and had it running a good part of the day( it's been hot).

Going to test drive home tonight. I'm leaning towards replacing the crank ref. sensor with harness if problem does not show again.

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1982 MBZ 300SD Turbo Diesel- just turned 200,000- just breaking her in