On Fri, 30 Jan 2004 20:43:46 -0800, "CaptainKrunch"
<nothing@nobody.com> wrote:

>It is like any other test. Like an EKG. It takes somebody that knows what
>they are doing in order to interpret the results correctly. Depending on
>whether overall compression is low or just an isolated cylinder or two would
>determine the fix.
>
>Pertaining to the other poster I have never heard of a running compression
>test. In as much as connecting a psi gauge to a cylinder and running the

Compression 1 2 3
4
Cranking 178 175 170
175
Idle 60 60 40
60
2000 RPM 40 40 20
20

May indicate valve or flat camshaft problem on #3.

In conjunction with a cylinder leakdown test, is very helpful for
identifying problems.

You may not be able to peform running compression tests on all
vehicles. Especially OBD-II which will catch the misfire, unless you
can disable the individual cylinder.

>engine minus that spark plug. If indeed this is the case that makes no
>sense because you would have a misfire with that cylinder and it would set
>off codes in the computer that would need to be reset. Mostly compression

Only on OBD-II Lots of pre-OBD-II cars out there which won't bat an
eyelash on a running compression test.

>tests are just done while cranking the engine over and disabling the engine
>so that it temporarily doesn't fire.

And disconnecting power to the fuel injectors.

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