02GTpit

i have a 2002 GT it sit for a little over 2 years it had a misfire so i dropped and cleaned the tank put a new fuel filter on and i replaced the plugs, coil packs injectors, crankshaft sensor and the cam sensor and its still reading a misfire first 1000rpm and misfire #3 cylinder so i did a compression test and #3 has none at all it dont smoke it dont make any tapping or any back firing but every time i take out the plug on 3 it has black gunk on it like tar and smells like gas can anyone please help.. thanks

JC316

No compression?!? As in 0PSI? Take it again to make double sure, but if there is 0PSI, then you have a big freaking problem. Either a very large hole in the piston, or the connecting rod completely shattered and the piston isn't moving.

Try taking the spark plug out of the hole, then sticking a long extension on top of the piston (Make sure it's a long one so it doesn't go down in the cylinder), then turn the engine by hand, see if the extension moves up and down.

02GTpit

to tell you the truth i dont know OPSI what that means but ive done a compression test again and still nothing ill try what you said if what you think could be wrong would i still be able to drive it cause a do every day it just gets bad mpg and not all power is there

Synyster06Gates

0 PSI. Like zero pressure reading on the gauge.

And stop driving, go get it looked at. By driving it, you are potentially causing way more damage.

98redstang

You have to be doing something wrong or youhave a very serious problem as stated above.

02GTpit

well im one of those guys that would rather do it them selves but i guess im gonna have to take it somewhere.. does anyone know if you gotta pull the motor to pull the heads ?

945LSTANG

you sure you are doing everything right? what are you using to test compression and how are you doing it?

02GTpit

a compression tester i got from autozone that you screw in where the plug goes and turn the car over for about 5 turns

JC316

The gauge reads in PSI. Mine averages 160PSI across all cylinders. If the needle on the gauge doesn't move, then yeah, there is an extremely serious problem.

The only thing that I know of that can cause that are:

1. Gigantic hole in the piston
2. Valves that are missing, or completely bent so they aren't closing
3. The connecting rod shattered and the piston isn't moving

Any of these represents a complete tear down of the engine. Or replacing the engine.

945LSTANG

and all of the other cylinders checked out fine? doesn't sound good man.