Engine reving before shutdown?
 

Just purchased 2005 6 speed, dealer tells me that I should rev the engine to about 5k rpms and shut down the engine as quickly as possible. Dealer says this will clear out injectors and increase mpg. My only concern is this good for the engine? Ive heard this can cause engine damage in piston engines. I realize the wenkle engine is a different horse altogether. Would like to hear if anyone else is doing this and if Im causing damage to the engine or anything else I may be unaware of. Not really concerned about better mpg, just want to make sure this is an acceptable shut down procedure.

I rev it to 3k everytime i shut it down just out of habit. Never had my car not start or flood. On a 2005 i would imagine the flooding issues are gone but maybe not. I'd do it anyway just to clear out the fuel in the injectors espescially on short trips where the car hasn't had time to warm up.

Always. Even if you have the latest re-flash just give it quick rev before you shut 'er down.

As far as I know, this was useful as an avoidance maneuver, before the M flash, when shutting the car down before it was fully warmed up. The idea being that after turning off the fuel, the momentum kept the rotor spinning long enough to help purge any raw gas from the chambers and plugs. This was their "fix" for the volume of service calls being generated by engine floods at that time. I'd say your dealer is operating on old information, and ebellishing it with details that didn't even apply in the beginning -- namely the injector info. I don't see why this would be any more beneficial for the injectors than rpm achieved in normal driving. Finally, it was 3 or 4000 rpm, not 5000.

I don't see any use for this with a warmed-up engine. It may have some use when shutting down a cold engine but the flooding problems have largely been solved. The best things you can do to avoid flooding are 1) make sure you've got the current flash and 2) make sure you've got a high-capacity battery.

If your engine gets up to normal operating temperature, how you shut it off is based on personal preference. Some people rev, some people don't.

While recent impovements have dramatically reduced the probability of flooding, Mazda still recommends avoiding "short trips". Its not that every "short trip" will end in a flood, but rather that any "short trip" can still end in a flood (no absolute fix).

See the post https://www.rx8club.com/showpost.php...&postcount=954 for Mazda recommendations relating to avoiding flooding from a "short trip". It includes a recommendation for reving before cutoff. This matches the contents of Mazda's "Product Update" DVD that was sent to RX-8 customers.

After 38K miles on my '04 I flooded mine for the first time a few weeks ago when I moved it to wash it in the driveway and shut it down before it had warmed up. It was my own fault but a good reminder that our wonderful little engine is so completely different. Great car. Great engine. Just don't shut it down cold and don't forget to blip the throttle a little before you turn the key off.

After 22K miles with no flooding, I did same thing as musclecar. Shut down cold after a wash, two days later(today) engine flooded. Car was flatbedded to dealer and battery and plugs were upgradaed. Will this prevent flooding?

My belief is the answer to your question is no. Mazda still warns against short trips even on brand new cars which I would expect to have the latest ECU flash, the upgraded plugs and the upgraded battery. Even the last page of the Mazda Service Bulliten for fixing a "Car cranks but no start" warns that short trips should be avoided.

There is still plenty of oil in the places it needs to be when the engine is rotating, so rev'ing it before shutting it down won't cause any harm. Its highly recommended to do so, but with the new flashes, its not as necessary. I use 3k myself. Rev to 3k, and as you let off the gas turn the key. This way the engine is decelerating as you cut spark. But warming up the car is more important. On cold days, I will rev the car in neutral at 3k at stop lights to accelerate the warm-up process. Once the engine starts to get warm, you can race the engine from 3-5k in smooth runs to warm it even quicker. I would suggest trying not to exceed 5k until the engine is at temp. and not to exceed 7k until it has been at temp. for at least 5 minutes. Those things will greatly prolong the life of your engine.

Just to add another what I do responses, the only time I rev to 3k for 10 seconds and shutdown is if the temp needle is not at the completely warm mark, if the car is completely warm just shut it off like any other car, it should be fine. Now I do not shut my car off if is anywhere close to the 2 marks that are at the "C" on the gauge.