It seems that every week someone asks how to do the ATF trick. I was bored one day and wrote this little description up, taking from several posts on the rx7 forum. This procedure has worked for me several times, but I disclaim all accountability for it right now. Do at your own risk.

The theory behind the "ATF trick" is to loosen up/dissolve the carbon deposits that are left inside engines. These deposits are particularly bad in a rotary engine, as when they form on the apex seal, they can cause it to get stuck. This can produce a lack of compression, and, therefore power. ATF acts as a detergent to help loosen these deposits up.

First, you need to buy some ATF. ATF is automatic transmission fluid. Any ole' ATF will work, but I prefer "Marvel's Mystery Oil" (MMO), as it was originally designed to be burned. It can be purchased at any walmart or auto parts store. 8 or 16 oz will do fine. You will also want to get 4 new spark plugs, as this procedure will foul them. Many people keep a set of old or bad plugs around just for this. Also helpful is a bit of hose (2 or 3 feet), and a little pump or a funnel.

You'll want to schedule this so as to leave the ATF sitting for as long as possible. At least 24 hours is necessary to get the best results.

Ok..on to the procedure. Remove your leading (LOWER) spark plugs. The goal now is to get some ATF directly into the combustion chamber. This can be accomplished via pumping it thru the hose, into the chamber, or using the funnel, or a turkey baster, or whatever. Squirt an ounce or two in the front housing, then into the rear housing.

Now, since our engies have three combustion faces on each rotor, we want to repeat this for each face. To expose the next face, you need to rotate your engine one full e-shaft cycle. NOTE: Remove the hose from the plug hole before doing this, or you WILL chop the hose off inside the chamber. To rotate the engine, you can take a wrench to the alternator pulley, and turn it. If the belt is tight enough, the main pulley should turn. You want to get exactly one full turn of this pully. The direction you turn doesn't really matter. After one turn, squirt more into the front and rear housings. Then, turn again, and squirt to do the third and final combustion face.

Now, we wait. Every 8 hours or so, (timing really isn't important..just let it sit as long as you can), go turn the engine another cycle. Turn it forwards and backwards a little, to sort of work the apex seals.

Ok..it's been in there for at least 24 hours.. Pull your EGI fuse (second from the engine end of the fuse box). Pull out a spark plug from each housing (you may have left them out initially--that's fine). You will probably want to put some paper towels down on the driver's side wheelwell, where the ATF is about to spray out. Crank the engine for a couple seconds--the ATF will spray out in liquid form, as well as some white smoke. Perfectly normal. The more ATF you get out now, the less will come out the exhaust in a minute.

Put the spark plugs back in, put the plug wires on. Put the EGI fuse back in. Move your car out of your garage! Actually, you may want to do this at night. You can now start your car, but beware--the largest cloud of white smoke you have ever seen will come out of the tailpipes. Not good if you have pesky neighbors.. ;) Drive the car around, letting it warm up properly (read: slowly). Once it's warmed up, beat the hell out of it. Hit redline a few times. It will continue to smoke for 10-20 minutes, depending on how much ATF you got out earlier. You may notice a large improvement in performance--I did. This is a nice time to go get your new spark plugs. :)

After the car cools back down, put your new plugs in. Keep your old ones for the next time you do the ATF trick. You're done!

As a side note, ATF isn't exactly "good" for your cataletic converters, nor the o2 sensor. Doing it once or twice won't DESTROY them, but will shorten their life. I have heard of people keeping a spare o2 sensor to use for this, but that's probably overkill.