Gen 4 Compression Test Instructions

[Rocket]

Thanks in advance for your help. Wanting to do a compression test and wondering what are the proper steps to do it? Fuses/relays to disconnect, etc, so it doesn't throw a bunch of additional codes?

Regards!

[Back In Black]

From the service manual.

39141

[Rocket]

Thanks BIB!!! Only thing I might do a little differently is to do this on a cold engine. Getting the plugs out is enough of a pain and taking them out on a hot engine and trying to do a compression test with headers would be ridiculous! And heck, with the hot weather we're having here in AZ, I could just open my garage door and let the sun beat on the engine for a few hours and it would be 150* anyhow 😎.

Thanks again!

[Old School]

Thanks BIB!!! Only thing I might do a little differently is to do this on a cold engine. Getting the plugs out is enough of a pain and taking them out on a hot engine and trying to do a compression test with headers would be ridiculous! And heck, with the hot weather we're having here in AZ, I could just open my garage door and let the sun beat on the engine for a few hours and it would be 150* anyhow ��.

Thanks again!
I'd do it cold too, won't be quite as accurate, but will identify a weak cylinder.