There are several "automatic" solutions that have been implemented over the years. One of them, in particular, stands out as being the best in my book.

In no particular order:

Fuel cut switch. Simple, works great, wouldn't fly on a factory car. "If your engine fails to start, toggle the switch to off, when the engine fires, toggle it to on." Not in this country...

Full throttle cranking cut: S5 & RX-8 use it. It works decently, but isn't a great solution IMHO because it requires the user to be aware of it. Again, not a lot of people care to pay that much attention to the car's manual.

Cranking delay fuel cut: Best solution, IMHO. The general idea is that if the engine has been cranking for a period of time (3 seconds IIRC), the fuel is cut off. This is the best solution I've seen, because it works with what people normally do. Engine doesn't fire over immediately? Keep cranking it to see if it will catch. Keep cranking, fuel gets cut, engine fires, release the key, fuel resumes, drive off. There are modules that can do this, and I've actually debated designing & selling one for the S4 owners.

-=Russ=-

 

Hmm dono if this one was posted, but check your timing. Seems like prevous owner set the timing wrong my car.. ie set trailing using leading mark on pully. Once I checked timing and set it back to factory spec my car wouldn't flood on cold starts.

 

It is just a frikkin characteristic of the rotary engine. Just deal with it people.

 

No, it's characteristic of a worn-out rotary engine or one with old parts that need to be serviced or replaced. You "deal with it" by rebuilding the engine or fixing the offending parts. Then you won't need any of these suggested band-aids.

 

What's wrong with you??? I guess if you have a leak in your boat (or perot in honer of our friends in New Orleans) you just deal with the leak??? Hey, I've got an idea. How about properly fixing the leak?

On the same note, How about fixing the problems....

Jeesh, "deal with it"

 

Any of you FLOODERS out there want to experiment??????

Answer if your flooding problem is as follows: Starts great in the morning or the first time you start the car that day. After driving the car for some time and turning it off, it won't start ten or fifteen minutes later and you have to use a fuel cut switch to start it.

If your flooding is other than the above, you don't meet the requirements so don't ask.

Oh, it would help if you have a basic digital meter and know how to depin a wire from the ECU plugs. Not a requirement, but would be helpful.

 

I have no new info to add but i wanted to back up the whole leaky injector/low compression ideas. When my old motor was going it used to flood 3-4 times daily. Im running a fresh rebuild (110 both rotors)with cleaned/mapped injectors and I have yet to flood once, im 3000miles into the rebuild.

 

What if during a morning cold start, the sensor wasnt working correctly and the ecu used its default (~176? degrees)? Wouldnt that have an effect?

 

YEAH!
I thought maybe I had dreamed that up.... ( but really, no I have used it before whenthe car has sat for more than 2 weeks.)
Works like a charm (darn leaky injectors)

yeah- well maybe if it was cleaned up a little, to be more concise.
Less opinion and more fact, and I think sticky is a good idea.(or maybe in FC archives)

|M|

 

Similar down here in a write up
http://www.racingrotary.com/floodfix.htm

You can control the relay in any way you want as long as it gets turned off while cranking the motor. Either wiring from the ECU, under the dash or from the power antenna plug in the rear like i did.

I dont think there is a "FIX" that isnt called a bandaid for this problem. I think its just how the ECU controls the injectors and when they fire and where the timing is set too. A real fix would be to replace the ECU with an aftermarket. I suppose that is the only "non bandaid" fix. Just like a SAFC is a "piggy back" and some people call it a bandaid performance item.

the floodfix has been working for the 2 years I have owned the car. Never floods.

My injectors were cleaned at RCENG and didnt leak when they were put in. still flooded. My fuel pressure died all the time when the engine was off because i had a few leaks. SO no fuel was leaking in the chambers.

I dont think so. Maybe , possibly, in archives. But not in a sticky.

 

I think Possibly that cracking the throttle open helps allow more air flow in allowing the AFR to not be as rich and helps starting. I think this because when my engine used to flood, either i do the fuse trick or hold teh pedal to the floor (I have a s4) or just crack the throttle a little bit. I cant be sure that it leans out the AFR during cranking but I think it does. Whats your take?

 

Quoted from the Training Manuals on page 4-38 in Fuel and Emmisions.

Interesting. Pretty much what i thought. Can we just have a resistor pack for the water thermo sensor when cranking the engine it tells the ecu the engine is warmer then normal? probubly harder to make then the relay flood fix.

 

If a 330 ohm resistor is installed in place of the water thermo sensor, and the flooding problem goes away, then it suggests there is something wrong in the water thermo sensor circuit. At least it does to me.

The 330 ohm represents a hot engine. See the specs for a water thermo sensor. This isn't suggesting a bandaid of resistors. A bandaid is dumping the stock ECU and buying a aftermarket.

 

well my thinking is that even if the water thermo resistor is in spec along with everything else. The computer still might be programed to injecto more fuel then is needed. And of course as compression lowers, the flooding could start to happen. I think we should look for a company to make some sensors with the right resistance for cold engines just brain storming. I know there is a company that does that and they probubly have one already. but probably not the right thread or electrical connector.

Im going to look into this further. Ill see if i can find that company again. See what they can do. I can send them a sensor too. I think I have a used one.

 

Resistance for Water Thermo Sensor
-20*C (-4*F) = 16.2k Ohm
20*C (68*F) = 2.45K Ohm
80*C (176*F) = 0.320K Ohm

If we were able to get a sensor that was maybe a lower resistance that it normaly would be for a given temp. Would this make the ECU inject less fuel then is normally being injected?

 

Lower resistance equals a lower duty cycle during the START cycle. Lower duty cycle equals less fuel. Less fuel equals a engine that won't flood.

I think its a sensor problem more than a low compression/leaking injector problem on some of the cars. NOT ALL THE CARS , but some.

I'm suggesting, that if someone has a car that once fully warmed up/hot, has the characteristic of not starting when fully heated up, that the probllem might be something other than flooding due to low compression. I'm suggesting the ECU is seeing a figure from the water thermo sensor other than what the temp really is. I'm suggesting that temp figure is much, much lower than the real temperature. The lower *seen* temperature will cause the ECU to inject much more fuel than needed and THAT causes the flooding.

I tried this idea out on a car that is known to not start when its up to working temperature and needed a fuel cut switch to get started again. This car also ALWAYS started when cold.

INstalling a 330ohm resistor in place of the water thermo sensor resulted in the car starting each and every time once hot. Hot as in up to 190*. Common sense says the water thermo in that car is bad..........but it reads approx .4 vdc at that temp at the ECU and that is a normal reading for that temperature

I'm going to just go ahead and buy a new waterthermo sensor for that car and see what the deal is. I'm also thinking about using the present water thermo sensor but instead of using the existing ground for that sensor, I'm going to ground it directly to the engine or chassis.

Normally that ground is spliced into the other sensors grounds and routed back to the piin 2C on the ECU where it is finally grounded. thru the ECU. I'm thinking there's some interference being picked up on the common ground circuit used by all the sensors.

If you look at a series four schematic you'll see all the sensors are spliced into a common brown/black wire (on a 87 schematic anyway, pure black on a 88 car).

And again, I've looked at the sensor the car I mention above and it SEEMS flawless. Key word....seems.

 

Exactly. I have a brand new water thermo sensor in my engine and it still flooded. Although the compression was between 85-90 (S4) which might of had some to do with it. I think the best way is to shut the fuel pump off during cranking. I say this cause even if you start injecting the right amount of fuel, what happends when you shut the car off without it warming up? Now i know you should never ever do this. Usually the next time it floods from more fuel being injected in. So if you shut the fuel pump off during cranking this wont happen. Well it will flood but it will clear its self very quickly and start up on residual pressure if any is in the fuel system.

After installing the 330 ohm resister. Try starting the engine stone cold. If you can in weather below 40*F. Curious.

 

A 330 ohm resistor in place of the water thermo sensor will result in you being damn lucky if the car will start. Ain't a gonna happen at 40 degrees. Instead of a 330 ohm resistor the same effect can be had by just depining the water thermo wire at the ECU. The ECU will default to 176 degrees and you'll get a 176 degree duty cycle during start. Not enough fuel to start.

Insert a 2-3K ohm resistor and it'll fire right up.

I have a engine that always started when cold, but if driven hard and the water temps get up, and you turn the engine off, it's very rare it would start. So I find that if I install a 330 ohm resistor in place of the water thermo senso rthe car starts up each and every time without fault, when hot. Hot being b/t 180-195 degree range. I even installed a 220 ohm resistor and it still started after being hot.

Those 220 and 330 ohm are the only resistors handy right now. That's the main reason they were picked. Plus the 2.2K used this morning to start the car.

https://www.rx7club.com/forum/attach...hmentid=146665
The resistors are not a fix. They are just a tool to find out why that car did not start when hot. To me it's a water thermo sensor or its electrical circuit. To me, using the 330 ohm or 220 ohm resistor, shows that if the ECU recieves the right resistance from the water thermo sensor, then there is no problem. The ECU must have been seeing some wrong figure. A much higher resistance figure that causes too much fuel to be injected.

Like I said, I never ever had a cold start problem, only when hot.