Thanks, Rotarygod!... How to resurrect your flooded RX8 in ten minutes or less!
12-22-2010, 10:39 PM
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Starting a Mazda Rx-8 with a Flooded Engine
I just moved to the East Coast from Arizona, so this is my first experience with this car in the cold. Subsequently, if I don't park in the garage right after work for whatever reason I keep pulling the car into the garage later without running it long enough, and without fail I come out to a flooded car in the morning. I do the Mazda gas smash and it works every time. When the gas is held wide open for 10 seconds, the fuel is shut off. When the fuel is cut, you can hear the engine start to spin faster. I stay on the starter for another 10 or 15 seconds. So in the engine is cranking for about 30 seconds in all. Then let the car sit for a minute or two and start the engine normally. It sounds really sluggish and it can take up to three attempts through the entire evolution, but it works every time. I think the major problem is people are only cranking the engine for 10 seconds; this is when the fuel is cut. The engine needs to run longer to evacuate the residual fuel.
12-23-2010, 01:23 PM
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kevin@rotaryresurrection
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I just moved to the East Coast from Arizona, so this is my first experience with this car in the cold. Subsequently, if I don't park in the garage right after work for whatever reason I keep pulling the car into the garage later without running it long enough, and without fail I come out to a flooded car in the morning. I do the Mazda gas smash and it works every time. When the gas is held wide open for 10 seconds, the fuel is shut off. When the fuel is cut, you can hear the engine start to spin faster. I stay on the starter for another 10 or 15 seconds. So in the engine is cranking for about 30 seconds in all. Then let the car sit for a minute or two and start the engine normally. It sounds really sluggish and it can take up to three attempts through the entire evolution, but it works every time. I think the major problem is people are only cranking the engine for 10 seconds; this is when the fuel is cut. The engine needs to run longer to evacuate the residual fuel.
It's not just a matter of pumping air through the engine in an attempt to push away the excess fuel, which is what the above description does.
Since I havent seen it posted in this thread, I will explain what causes flooding from cold shutdown. Then you will understand why the above procedure can only be successful in mild flooding situations, and why colder weather can cause a more severe flood.
Engines, piston or rotary, require more fuel when cold than when hot. We're talking about not only coolant (engine) temperature, but ambient air temps also. As the engine temperature warms up, the computer leans out the fuel mix because the engine needs less to stay running properly at warmer temps. Bear in mind that rotaries tend to require more fuel than most piston engines at any given time. So, the cold condition in a rotary engine runs VERY RICH.
Engines, piston or rotary, require a coating of oil between sealing surfaces, in order to make sufficient compression. In piston engines this occurs naturally as the crankcase oil gets splashed or carried up onto the cylinder walls. In a rotary there is NO NATURAL SOURCE of oil coating on the rotor housing-to-apex seal surface, or the corner/side seal-to-iron housing surface. So, we have to pump it in to our engines via the OMP, but it is still a very minute amount and in stock form is barely adequate to the task of long term lubrication of the seals.
In any case, what do you think happens to that coating of oil when the rotary is started in a cold weather, cold engine scenario? All that fuel comes in and washes it off, just as if you'd pour solvent on an oil spill on your garage floor. The engine is already running so it has enough dynamic compression at that point to continue running. And, if left to run until it completely warms up to operating temperature, the fuel mix will lean out to the point that it stops washing away the oil from the OMP...the coating of oil is restored.
IF the engine gets shut down, it relies on that coating of oil to help it start back up again. You need a certain level of compression, and that oil coating helps seal small gaps between housing walls and rotor seals, helps raise compression and helps the engine start. Let's say the engine is at operating temp. The coating of oil still exists and the engine should restart later with no problems. Let's say the engine is still in the RICH cold start cycle. The coating of oil is temporarily washed away, so if you shut it down now, it will have greatly reduced compression when you attempt to start it later, and so it probably will not start. You wind up with more fuel injected, than compression to ignite it, which is what we call "flooded".
Coincidentally, we inject more oil into the chambers to clear the flood. The reason this works so well is because it establishes this coating of oil again and raises compression temporarily so the engine can start again.
Now obviously there are many variable points in between the COLD and OPERATING TEMP conditions. There are points that exist which could result in varying severities of flooding conditions, or not at all, even though the engine is still not fully warmed up. Every engine has different fueling needs and different compression values, so these points and conditions will vary a bit from engine to engine...one engine may flood easily while another may be more resistant.
Its in this middle ground where a "light" flood can occur. That is, the engine wasn't at full operating temp yet, and it doesn't restart on the next try, but the flood condition is not so severe as to require the injection of more oil into the chambers. These conditions are what the mazda PCM "fuel cut on full throttle" feature is for, and helps to alleviate.
Interestingly enough, I theorize that flood prevention may be yet another added benefit to premix/2 cycle oil in the fuel. By injecting the oil at a static ratio with the fuel, you bypass this problem entirely. IF you're injecting a lot of fuel, you're also injecting more oil, and so by definition the fuel cannot wash away the oil coating, because the fuel CONTAINS the oil coating. A rich fuel mix also means an equally rich oil mix. So in theory you should never be able to flood a rotary running premix by shutting it off while cold. I've started my own rx8, which runs 2 cycle in the fuel religiously, and shut it down cold many a time, and have never once flooded it in the least bit. I realize this is only one sample of the hundreds of thousands of these cars out there and cannot be taken as PROOF of this theory, but it is definitely interesting to think about and try.
12-24-2010, 07:24 AM
#31
Registered
This will not always work for a severely flooded engine. Perhaps you are not encountering temperatures cold enough to contribute to a severe flood.
It's not just a matter of pumping air through the engine in an attempt to push away the excess fuel, which is what the above description does.
Since I havent seen it posted in this thread, I will explain what causes flooding from cold shutdown. Then you will understand why the above procedure can only be successful in mild flooding situations, and why colder weather can cause a more severe flood.
Engines, piston or rotary, require more fuel when cold than when hot. We're talking about not only coolant (engine) temperature, but ambient air temps also. As the engine temperature warms up, the computer leans out the fuel mix because the engine needs less to stay running properly at warmer temps. Bear in mind that rotaries tend to require more fuel than most piston engines at any given time. So, the cold condition in a rotary engine runs VERY RICH.
Engines, piston or rotary, require a coating of oil between sealing surfaces, in order to make sufficient compression. In piston engines this occurs naturally as the crankcase oil gets splashed or carried up onto the cylinder walls. In a rotary there is NO NATURAL SOURCE of oil coating on the rotor housing-to-apex seal surface, or the corner/side seal-to-iron housing surface. So, we have to pump it in to our engines via the OMP, but it is still a very minute amount and in stock form is barely adequate to the task of long term lubrication of the seals.
In any case, what do you think happens to that coating of oil when the rotary is started in a cold weather, cold engine scenario? All that fuel comes in and washes it off, just as if you'd pour solvent on an oil spill on your garage floor. The engine is already running so it has enough dynamic compression at that point to continue running. And, if left to run until it completely warms up to operating temperature, the fuel mix will lean out to the point that it stops washing away the oil from the OMP...the coating of oil is restored.
IF the engine gets shut down, it relies on that coating of oil to help it start back up again. You need a certain level of compression, and that oil coating helps seal small gaps between housing walls and rotor seals, helps raise compression and helps the engine start. Let's say the engine is at operating temp. The coating of oil still exists and the engine should restart later with no problems. Let's say the engine is still in the RICH cold start cycle. The coating of oil is temporarily washed away, so if you shut it down now, it will have greatly reduced compression when you attempt to start it later, and so it probably will not start. You wind up with more fuel injected, than compression to ignite it, which is what we call "flooded".
Coincidentally, we inject more oil into the chambers to clear the flood. The reason this works so well is because it establishes this coating of oil again and raises compression temporarily so the engine can start again.
Now obviously there are many variable points in between the COLD and OPERATING TEMP conditions. There are points that exist which could result in varying severities of flooding conditions, or not at all, even though the engine is still not fully warmed up. Every engine has different fueling needs and different compression values, so these points and conditions will vary a bit from engine to engine...one engine may flood easily while another may be more resistant.
Its in this middle ground where a "light" flood can occur. That is, the engine wasn't at full operating temp yet, and it doesn't restart on the next try, but the flood condition is not so severe as to require the injection of more oil into the chambers. These conditions are what the mazda PCM "fuel cut on full throttle" feature is for, and helps to alleviate.
Interestingly enough, I theorize that flood prevention may be yet another added benefit to premix/2 cycle oil in the fuel. By injecting the oil at a static ratio with the fuel, you bypass this problem entirely. IF you're injecting a lot of fuel, you're also injecting more oil, and so by definition the fuel cannot wash away the oil coating, because the fuel CONTAINS the oil coating. A rich fuel mix also means an equally rich oil mix. So in theory you should never be able to flood a rotary running premix by shutting it off while cold. I've started my own rx8, which runs 2 cycle in the fuel religiously, and shut it down cold many a time, and have never once flooded it in the least bit. I realize this is only one sample of the hundreds of thousands of these cars out there and cannot be taken as PROOF of this theory, but it is definitely interesting to think about and try.
It's not just a matter of pumping air through the engine in an attempt to push away the excess fuel, which is what the above description does.
Since I havent seen it posted in this thread, I will explain what causes flooding from cold shutdown. Then you will understand why the above procedure can only be successful in mild flooding situations, and why colder weather can cause a more severe flood.
Engines, piston or rotary, require more fuel when cold than when hot. We're talking about not only coolant (engine) temperature, but ambient air temps also. As the engine temperature warms up, the computer leans out the fuel mix because the engine needs less to stay running properly at warmer temps. Bear in mind that rotaries tend to require more fuel than most piston engines at any given time. So, the cold condition in a rotary engine runs VERY RICH.
Engines, piston or rotary, require a coating of oil between sealing surfaces, in order to make sufficient compression. In piston engines this occurs naturally as the crankcase oil gets splashed or carried up onto the cylinder walls. In a rotary there is NO NATURAL SOURCE of oil coating on the rotor housing-to-apex seal surface, or the corner/side seal-to-iron housing surface. So, we have to pump it in to our engines via the OMP, but it is still a very minute amount and in stock form is barely adequate to the task of long term lubrication of the seals.
In any case, what do you think happens to that coating of oil when the rotary is started in a cold weather, cold engine scenario? All that fuel comes in and washes it off, just as if you'd pour solvent on an oil spill on your garage floor. The engine is already running so it has enough dynamic compression at that point to continue running. And, if left to run until it completely warms up to operating temperature, the fuel mix will lean out to the point that it stops washing away the oil from the OMP...the coating of oil is restored.
IF the engine gets shut down, it relies on that coating of oil to help it start back up again. You need a certain level of compression, and that oil coating helps seal small gaps between housing walls and rotor seals, helps raise compression and helps the engine start. Let's say the engine is at operating temp. The coating of oil still exists and the engine should restart later with no problems. Let's say the engine is still in the RICH cold start cycle. The coating of oil is temporarily washed away, so if you shut it down now, it will have greatly reduced compression when you attempt to start it later, and so it probably will not start. You wind up with more fuel injected, than compression to ignite it, which is what we call "flooded".
Coincidentally, we inject more oil into the chambers to clear the flood. The reason this works so well is because it establishes this coating of oil again and raises compression temporarily so the engine can start again.
Now obviously there are many variable points in between the COLD and OPERATING TEMP conditions. There are points that exist which could result in varying severities of flooding conditions, or not at all, even though the engine is still not fully warmed up. Every engine has different fueling needs and different compression values, so these points and conditions will vary a bit from engine to engine...one engine may flood easily while another may be more resistant.
Its in this middle ground where a "light" flood can occur. That is, the engine wasn't at full operating temp yet, and it doesn't restart on the next try, but the flood condition is not so severe as to require the injection of more oil into the chambers. These conditions are what the mazda PCM "fuel cut on full throttle" feature is for, and helps to alleviate.
Interestingly enough, I theorize that flood prevention may be yet another added benefit to premix/2 cycle oil in the fuel. By injecting the oil at a static ratio with the fuel, you bypass this problem entirely. IF you're injecting a lot of fuel, you're also injecting more oil, and so by definition the fuel cannot wash away the oil coating, because the fuel CONTAINS the oil coating. A rich fuel mix also means an equally rich oil mix. So in theory you should never be able to flood a rotary running premix by shutting it off while cold. I've started my own rx8, which runs 2 cycle in the fuel religiously, and shut it down cold many a time, and have never once flooded it in the least bit. I realize this is only one sample of the hundreds of thousands of these cars out there and cannot be taken as PROOF of this theory, but it is definitely interesting to think about and try.
12-24-2010, 11:51 AM
#32
kevin@rotaryresurrection
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thanks a lot. That was perhaps the best explanation on the subject I've read so far! It also helped me understand better why the older piston engines with carburetors would be a struggle sometimes during cold weather - particularly back in the days where cars had no computers controlling air/fuel ratios.
So piston engines are always going to have their coating of oil or compression. The old carbureted cars were hard to start because carbs aren't that accurate at all, and of course they aren't tuned or adjusted to different atmospheric conditions such as barometric pressure, air temp, etc. So you tune them for the best 'average" conditions you can predict when they leave the factory, and if the weather gets outside of a certain range, well then performance and driveability suffer a lot.
Also bear in mind that on most old carb'd v8's the intake manifold has runners that are a mile long. Carbs don't atomize fuel very well at all especially at low rpm (such as startup) so it winds up being just like you poured some liquid fuel right down the intake. It just runs through the runners and eventually drips into the cylinders. It's not a fine mist so it doesn't ignite as easily. This makes starting hard as well, and makes them prone to flooding.
12-26-2010, 05:01 PM
#35
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Well, that subject is really quite a bit different. In a piston engine you are almost always going to have your natural coating of oil between piston ring and cylinder bore wall....so compression should not be an issue. Exceptions are probably only present when you have really worn out rings due to high mileage or poor oil change habits...or a bad headgasket that lets coolant into one or more chambers and the coolant washes away the coating of oil...or a leaking carb or fuel injector letting fuel drip in through an open intake valve.
So piston engines are always going to have their coating of oil or compression. The old carbureted cars were hard to start because carbs aren't that accurate at all, and of course they aren't tuned or adjusted to different atmospheric conditions such as barometric pressure, air temp, etc. So you tune them for the best 'average" conditions you can predict when they leave the factory, and if the weather gets outside of a certain range, well then performance and driveability suffer a lot.
Also bear in mind that on most old carb'd v8's the intake manifold has runners that are a mile long. Carbs don't atomize fuel very well at all especially at low rpm (such as startup) so it winds up being just like you poured some liquid fuel right down the intake. It just runs through the runners and eventually drips into the cylinders. It's not a fine mist so it doesn't ignite as easily. This makes starting hard as well, and makes them prone to flooding.
So piston engines are always going to have their coating of oil or compression. The old carbureted cars were hard to start because carbs aren't that accurate at all, and of course they aren't tuned or adjusted to different atmospheric conditions such as barometric pressure, air temp, etc. So you tune them for the best 'average" conditions you can predict when they leave the factory, and if the weather gets outside of a certain range, well then performance and driveability suffer a lot.
Also bear in mind that on most old carb'd v8's the intake manifold has runners that are a mile long. Carbs don't atomize fuel very well at all especially at low rpm (such as startup) so it winds up being just like you poured some liquid fuel right down the intake. It just runs through the runners and eventually drips into the cylinders. It's not a fine mist so it doesn't ignite as easily. This makes starting hard as well, and makes them prone to flooding.
Thanks for sharing the info man.
02-15-2012, 03:36 PM
#36
Resu Deretsiger
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Came home after 7 months deployed to a car that wouldnt fire. Tow start worked like a champ, minus the icy roads; kept breaking the rear end loose and going sideways, but eventally i found enough traction to let first gear start the car. Runs beautifully now! Thank you for the pointers on this one!
08-07-2014, 10:19 PM
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Car wash becomes wash out.
This past weekend my girlfriend's son text her, while we were out of town, and asked if he could use her RX-8 to go to the mall. I told her not to let him, but she did anyway as long as he filled it up and washed her. Normally he hand washes his car in our driveway and her car. But this time he decided to go to the automatic car wash. He drove it the 6 miles home and shut it off. Then went to leave 15 minutes or so later and it wouldn't start. My gf is stubborn and wouldn't let me pull the plugs out and clean them and clean out the cylinders, like I wanted. She cranked and cranked it using the pedal method till she ran the battery down, even with my jumpers hooked up to it. I finally told her we were done for the night and pushed it up to the garage and put the charger on it for the night. I went to work the next morning and she calls and says she got it started. But she also said the temp gauge rose very fast and she got scared and shut it off. Of course then it wouldn't start later.
So when I got home we tried and cranked and cranked till the battery was almost dead again. I sent her in the house and jacked the front up, pulled the left front off and pulled the plugs. Full of gas and oil, burnt them off with my propane torch blew the excess out of the rotors, put the plugs back in and she fired right up. She smoked really bad. It was more like steam and smelled like antifreeze. It took forever to burn off. I dumped almost a gallon of water in the coolant jug. We drove it into town to the store 15 miles away. Did a little shopping and started her back up and drove home. That was 2 days ago. Today i went out to start it and it was flooded again. Anybody heard of blowing a head gasket going through the car wash or anything similar?
So when I got home we tried and cranked and cranked till the battery was almost dead again. I sent her in the house and jacked the front up, pulled the left front off and pulled the plugs. Full of gas and oil, burnt them off with my propane torch blew the excess out of the rotors, put the plugs back in and she fired right up. She smoked really bad. It was more like steam and smelled like antifreeze. It took forever to burn off. I dumped almost a gallon of water in the coolant jug. We drove it into town to the store 15 miles away. Did a little shopping and started her back up and drove home. That was 2 days ago. Today i went out to start it and it was flooded again. Anybody heard of blowing a head gasket going through the car wash or anything similar?
08-20-2014, 05:12 PM
#38
05 Shinka #363
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This video is a great demonstration of the deflood with the pedal method and it worked for me. I have a 2005 Shinka and I drove into a very deep puddle (knee deep) during heavy rains this past weekend. I had 4 inches of water in the back and front floor and after taking everything I could off to dry in the engine compartment and even connecting my wet vac to the tail pipes to suck out a lot of water (quarts) and even pulling the plugs for a few days to do everything possible to help it start it was a total failure, no starting. Then I found this video in a last ditch effort to avoid going to the dealer (who probably would have wanted to replace the engine). I followed the instructions to the letter. I kept trying but it wasn't starting. When the battery started to die I put jumper cables to my truck and tried 5 more times but it wasn't starting. I figured I'd pull the plugs and put some oil in but thought "OK, one more try". VROOM. Stick with it, you may have other issues that may be your problem but this worked for me. I still had water coming out the tailpipes though.
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