COMPRESSION TEST (HOW-TO)

It sounds easy to do but I've never done it before.

Here's what the Service Manual says...
COMPRESSION PRESSURE CHECK
1. Before inspection, check that the engine oil, starter and battery are normal.
Also, set the vehicle in the following condition:
- Engine coolant temperature: 80 - 95*C (176 - 203*F)
- Lights and all accessories: OFF
- Transaxle: "P" range
2. Disconnect the spark plug cables.
3. Remove all of the spark plugs.
4. Disconnect the crankshaft position sensor connector.
NOTE: Doing this will prevent the engine controle module from carrying out ignition and fuel injection.
5. Cover the spark plug hole with a shop towel etc., during cranking. After the engine has been cranked, check for foreign material adhering to the shop towel.
6. Set the compression gauge to one of the spark plug holes.
7. Crank the engine with the throttle valve fully open and measure the compression pressure.

Here are the 2 other posts on the subject...
http://66.98.150.64/~clubtgc/forum/viewtop...pic.php?t=10837
http://66.98.150.64/~clubtgc/forum/viewtop...opic.php?t=7077

LAYMANS TERMS (I'll edit this as I go)
1. Pull the plugs, wires, coil packs (if applicable)
2. Either pull the fuel injector fuse or the actual fuel injectors? (not sure on this one)
3. Screw in your compression gauge into one of the spark plug wells.
4. Crank the engine (make sure the throttle is open all the way)
5. Record the highest pressure of each cylinder.
6. Compare results.

Will I get a "Check Engine" light? Do I have to reset the battery?

Is this right? What about step 2? What do I do so fuel won't go everywhere?

What about the wet test? Do I just add some oil in the well? How much?

What about the dynamic test? I leave the other plugs and wires in but do I ground the rogue wire?

When I figure this out, I'll edit this post as a tutorial...

-MIKE.

For step 2 - pull the fuel pump relay under the hood to cut fuel. Do not "pull" any injectors.

http://myweb.cableone.net/jcopley/relay.jpg

what you are looking for is 190-210 across all cylinders and ideally no more than a 2-5% variance between your highest and lowest values. I think if you see anything below 190 - and def. if you see anything around 180 - you need to do further testing to see if you have a problem with rings, seals or worse.

As far as the "wet" or "dynamic" test, I'll leave those for someone else as I have no idea what you mean. :wink:

J

If the first test shows a problem then do the wet test, just squirt a little oil into the low cylinder(about a tablespoon), that will seal the ring and when you do the test again if the compression reading is higer than it is a bad ring.

:oops: Oops thats a couple years old :oops:

lol - yeah - but not a bad thread to revive....

J