Youngkyun739

heya, Im looking to buy a rx8 and I've come across this flooding problem. I tried the search and that sticky, but I don't seem to understand.

Can someone give me a difinitive and easy to understand answer to what flooding is? Not very car-lingo orientated; I dont understand what cold starts and warm turn offs are

thanks in advance

w2aew

Here's my description without putting too much technical jargon into it...

Flooding is when the combustion chamber (the place in the engine where the fuel-air mix is ignited and goes boom!), gets loaded up with raw, unburned fuel. Remember, that gas in liquid form does not burn (really!), it is only when it is in vapor form that it burns.

When raw, unburned fuel is in the combustion chamber, it wets down the spark plugs and essentially shorts them out - in other words - no spark! No spark, no ignition, no boom!

Another consequence of flooding a rotary is that the seals gets washed down with fuel and loose their ability to build compression (squeezing the air-fuel mixture prior to ignition) which is a requirement to running.

When the engine is cold, it is difficult to atomize the fuel (create an air-fuel vapor mixture). As a result, some raw fuel droplets form in the combustion chamber. If the engine shuts down or is turned off before this raw fuel is consumed, or before the engine temperature is high enough to prevent the droplets, it is possible that these droplets will wet the plugs and cause the "flooded" condition when trying to start.

A "cold-start" is simply starting the car when the engine is completely cooled - such as after sitting for many hours or overnight. A "warm" turn-off is simply shutting the engine off after it has reached normal operating temperature.

MEGAREDS

Flooding is the inability to start the car because unburned gasoline is left in the rotor chamber. Ideally, all the fuel should burn away in the hot chamber, but if the car is turned off when the engine is cold, conditions are such that the car won't always start the next time. It appears that about eighty percent of forum members have not had a problem. The other twenty percent have either figured out how to get their cars started themselves or had it towed, which Mazda is covering under the warranty.

The condition in the 8 may actually be a "fouling" of the plugs... fuel is splashed onto the spark plugs, and if it doesn't get hot enough for the fuel to burn away, the moisture prevents the necessary spark. Because the rotors are sealed, the fuel doesn't evaporate, so you just can't wait the problem out.

The solution is to be sure the car always gets to operating temperature, so fuel is never left in the rotor. Consensus is that rotary "flooding" is not a defect in the car or design, since previous rotary cars all had the same problem. If it could be "fixed," they would certainly have done so by now. In my mind, its just a design limitation, but...

The new "M" flash is supposed to help the problem, but there has been at least one user whose reported flooding after getting the M flash. I suspect the M flash helps, but doesn't mean the car can't flood.

Youngkyun739

thanks for the replys!

Mikelikes2drive

don't worry too much about flooding young especially out here in warm sunny socal :D to prevent yourself from flooding just be careful and dont shut off your engine when its cold. simple

newtlicious

I learned a trick elsewhere that seems to make sense. If I must shut down when not completely warm, I blip the throttle to about 4000 RPM and shut it off at this rpm. The rotors continue to spin after you kill it and it clears all the chambers a few times before the engine comes to a stop. This prevents a cold, rich charge from being trapped against the plugs. Out of habit, I do this even when it's warm. No flooding and my car starts in one or two revolutions every time. Just blip it and turn off the key when it hits 4k.