Re: What does "No compression" mean?

air coming out the spark plug hole does not mean you have compression. If 
the rings are worn or the valve is bad, you can not take advantage of  the

"compression" of the explosion in the cylinder.  It will blow by the rings

or the valve and give you little or no power in that cylinder.
The air you hear coming out the spark plug hole is only a ****tion of the 
compressed air the would otherwise be used to turn your crankshaft.

"Programbo" <programbo5@[EMAIL PROTECTED]
> wrote in message 
news:93f2e598-60c1-4e93-9765-21c51a8286c9@[EMAIL PROTECTED]
> My 1994 Jeep Cherokee (Inline 6 4.0) started running really rough last
> week as if one of the cylinders was missing. I changed all the plugs
> and wires and cap/rotor and that fixed nothing. I was thinking maybe
> an injector wasn`t working and turned the Jeep on and unplugged each
> injector one at a time. Unplugging 4 of them made the engine start to
> die off right away but the #2 and #3 injectors didn`t seem to change
> anything when I unplugged them. So I figured those injectors were dead
> and replaced them. No change again. Still running really rough. (I
> know it was stupid wasting money but I really needed to try and get it
> running as I had a trip down the highway I had to take on the
> weekend.) I finally got tired of messing with it and took it to a
> repair shop and the guy there called and told me, "There`s no
> compression in those two cylinders." To make a long story short I just
> told him to leave it alone and I`d come pick it up. But today I was
> off work and went out to mess with it and I unplugged and removed the
> 2 spark plugs for those 2 cylinders (They were black with soot) and
> when I fired the Jeep up there was a lot of air being pushed out of
> the plug holes as the engine stroked. So I guess my question is: Isn`t
> that compression? I`m trying to eliminate possible simple fixes before
> junking this thing. Thanks for any input. 

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