1992 190E-2.3, I disconnected the ignition-coil wire to check the compression test of the cylinders. After I finished and connected everything back the car wouldn't start (no spark). The car was running fine before. I may not have grounded the ignition-coil wire properly during the test. A mechanic suggested the "ignition control unit" may have blown, therefore I replaced it with a used part from a junk yard, but it didn't solve the problem. I checked the ignition coil with an ohm-meter and it's almost within specs, the primary contact is 0.7 ohm (spec is 0.3-0.6 ohm) and the secondary is 11,100 (spec is 8,000 - 13,000 ohm). Is the coil bad for having 0.7 ohm (slightly out of spec)? Does any body have an idea how to diagnose this problem, before I start replacing everything? Thanks in advance.

For future reference, when anyone runs a compression test, disconnect the four pole connector at the EZL. This removes 12V power from the EZL, which completely disables the ignition system. Just disconnecting the coil wire can damage some electronic ignitions, so you want to remove power from them completely.

As an alternative, disconnect the coil wire from the distributor, attach it to a spark plug, and ground the spark plug with a clip-on test lead, and be sure there are no fuel vapors in the area that could ignite!!!

Duke