Took my 93 Rx-7 to the tracks yesterday for a couple runs. First run was great. I kept up with a supercharged Corvette to within fractions of a second for the first 1/8th of a mile. The second run seemed fine and when I pulled up to get my time slip and let the enginge rev down to idle, it started shaking bad. It was shaking in a pattern as opposed to random and chaotic jolts. The whole exhaust rattles and shakes under the car. It idles with less vacuum pressure than before. The car drives great once its in motion and at a stop light, if you give it a little gas, the rattling and shaking goes away. I have no idea what happened and would apprectiate any help. Thanks!

uh oh

sounds like a hose popped off. check the hose for the map sensor, brake booster, ect. with the car at idle, listen under the hood for a hissing sound, which will lead you to the vaccum leak

can you hear any 'clunk-clunk-clunk' sounds while the car is idling?

what did it idle at before and what does it idle at now?

vacuum pressure before and vacuum now?

Yes, there is a definite and apparent *clunk-clunk-clunk* sound. The car starts up UGLY. It idles at the same RPM but vacuum pressure before the problem was -45 cmHg and now its about -31 cmHg. For some reason, if you kick the RPMs up at a stoplight, the shaking goes away and the vacuum jumps back up to around -40 cmHg. Since the incident, the shaking and vibration seems to have gotten better. Anymore ideas and educated guesses would be appreciated.

Might have cracked an apex seal. Pull the spark plugs out one rotor at a time and crank it with the egi fuse out. Listen for smooth, consistant wooshes.