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
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.
*I make no claims as to the accuracy of this. It worked for me, it may not
work for you. Don't sue me.*