Help! I think I blew my motor!

So, your motor is idling funny after racing that Honda. Well, first things first, let's check the easy stuff, and make SURE of the situation with a compression test. This will tell you for sure if there's a problem.

9 times out of 10, it's something simple. Look under the hood - it's not uncommon for turbo cars to pop a vacuum line or intercooler hose off under boost. A vacuum leak can make the car idle funny, not idle at all, run weird, etc. - similiar symptoms to a blown motor. Go here and read up on diagnosing vacuum leaks.

OK, so you need to test your car to make sure the compression is what is should be. Here's what to do:

Get a regular compression tester from an auto parts store, preferably one that has a relief valve in the side. Mine's a Sunpro or something like that.

Remove the top 2 spark plugs (the trailings). Disable fuel and spark - I like to unplug the crank angle sensor and unplug the airflow meter, just to be 100% sure. Screw the compression tester into one of the spark plug holes. Have a buddy get in the car, floor the gas pedal, and crank it. Hold the relief button down on the compression tester - it's like a little bleeder valve on the side. Watch the gauge - you should see the needle bouncing. Look for consistent bounces. If you see low-low-HIGH-low-low-HIGH, that's a broken apex seal. The 2 combustion faces between the broken apex seal are leaking into each other, causing 2 low bounces and one high bounce.

After doing the bounce test, have your buddy crank the car with the gas floored again, this time not holding the bleeder button down. Let the compression tester build up to its highest reading. On a healthy motor, I usually see 100-110 psi or so. 90 and below is usually a weak motor, and even less if there's a bad apex seal (didn't pass the bounce test).

Repeat the test for the other rotor. It's VERY rare that both rotors are blown - this way you can compare the readings.

The Mazda compression tester can actually give numbers for the compression of each rotor face - much more accurate, but the tester is big bucks, and taking the car to the Mazda dealer for the test is, well, against my religion :).

Good luck! If your motor IS bad, don't panic! Take some time and figure out a game plan - if you're gonna rebuild it, get a core motor to swap in, a Jap-spec motor, whatever. It's not the end of the world!