PLEASE :) Compression test - how to disable ignition? m52

[JamesE30]

Hi guys I want to run a compression test on my m52 asap to try and diagnose some issues.

Could somebody please tell me exactly what to unplug to disable the ignition system?

I have searched and have had multiple posts saying, the fuel pump relay, the distributor, fuse #9 etc etc, but no picture or specific information.

this is my engine bay. The car and 24v are completely new to me thank you for your time!

[Northern]

probably lots of other ways to do it too, including unplugging the coilpack harness, and pulling fuel pump relay so you don't waste fuel.

[staysideways]

Exactly what northern said but be sure to know which coil pack came out of which cylinder and same with spark plugs. While ur there inspect the coil boots for any tears and inspect you spark plugs. A cars plugs say ALOT about the way it works. Hope i helped :)

1989 E30 325i Sedan Alpine

[AndrewBird]

Compression test should be done with all spark plugs out, so that disables the ignition system pretty well. lol Pulling the fuel pump relay will also kill fuel so you aren't soaking the cylinders down.

[JamesE30]

Thanks for the replies guys :up:

[M3PO]

Yes, you need to disable the fuel pump so you don't wash down the cylinders with fuel.