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An ecu fix to flooding issues

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Old Dec 18, 2003 | 01:37 AM
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An ecu fix to flooding issues

Canzoomer or anyone else who can do this for that matter, as many people have already figured out the rotary is much more prone to flooding than other types of engines. In the tech section I have written about how and why this takes place and some possible solutions which brings me here.

There is an ecu mod for the 2nd gen. RX-7 that allows fuel to be completely cut off at startup as long as the throttle is floored. This is a welcome addition for those cars since the way to unflood them was to pull the fuel pump fuses and crank the engine over for a few seconds to clear out any excess fuel. Then the fuse was replaced and the engine would hopefully start. With the ecu mod, the driver need only get in and floor it while trying to start it. Just hold the pedal down for a second or two and then take your foot off. The car always starts. How about an ecu mod like this for the RX-8? The fuel pump directly controls flow based off of input from the ecu so this shouldn't be too difficult. Obviously we wouldn't want the ecu to kill fuel flow anytime the car is floored but rather only while the started is engaged. This definitely seems like something worth pursuing. Many RX-8 owners would gladly pay a few extra dollars for this convenience rather than having to tow their cars in to get fixed.

Canzoomer, does this sound like something that you think would be feasible for the next batch, say Stage 1.2 or 2.2? Just something to consider. We'd love ya for it!
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Old Dec 18, 2003 | 04:57 AM
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Sounds like a great idea.
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Old Dec 18, 2003 | 05:55 AM
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Maybe I'm misunderstanding your post, but what you're describing sounds like what the 8 already does! The owner's manual describes a procedure for clearing a flood that involves cranking the starter with the accelerator floored...which cuts the fuel pump. Isn't that what you're asking for?
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Old Dec 18, 2003 | 12:06 PM
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This is what the rx-8 does, floored while starting cuts off the fuel.
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Old Dec 18, 2003 | 12:08 PM
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No ****!!! I was not aware of that. That's what I get for only having RX-7's.
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Old Dec 18, 2003 | 12:18 PM
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Originally posted by jtimbck2
Maybe I'm misunderstanding your post, but what you're describing sounds like what the 8 already does! The owner's manual describes a procedure for clearing a flood that involves cranking the starter with the accelerator floored...which cuts the fuel pump. Isn't that what you're asking for?
So, what is the procedure? Sorry, I don't have my owner's manual now, but I wanna know it now. Thank you.
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Old Dec 18, 2003 | 12:20 PM
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If you flood the engine, you're supposed to crank it for 10 seconds with the accelerator floored, then crank normally. I had to repeat this a few times when I flooded mine, but it did work eventually.
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Old Dec 18, 2003 | 01:06 PM
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Its called "de-choke" and it has been a regular part of ALL Mazda ECUs since 1993 that I have worked with (MX-3, MX-6, 626, 929, Millennia, Protegé, Miata, MPV and Tribute as well as the Ford Probe).
I'm not sure how the RX-7 would have managed to get around having that code in the ECU. Might have something to do with the RX-7 being developed without the interference of Ford which was present in all other models since then (and before, actually).
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Old Dec 18, 2003 | 02:46 PM
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Originally posted by rotarygod
No ****!!! I was not aware of that. That's what I get for only having RX-7's.
kouki FC's (89-91) also had the feature built in.
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Old Dec 18, 2003 | 04:46 PM
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The "second gen second gen" (89 to 91) as posted above had it, all 3rd gens had it, and now the 8 has it. When you hold the accellerator to the floor the fuel is shut off. That being said, DO NOT touch the accellerator when trying to start a cold engine, unless it is flooded. Then only hold it to the floor. When you think it's time to start it after clearing out the fuel, release fully.

I had a fuel pump switch in an 87 TII and it worked very well. I suppose you could add one to an 8, but it'd probably throw a CEL . The ECU keeps the car "under its' thumb".
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Old Dec 19, 2003 | 01:22 AM
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Originally posted by neofreak
kouki FC's (89-91) also had the feature built in.
I have an '89 T-II. My car does NOT have that feature! It is a very early '89 year model. My friend's 3rd gen never runs for long enough for me to know.
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Old Dec 19, 2003 | 02:39 AM
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HEY GUYS, ARE WE SAYING WE CAN FOREVER AVOID FLOODING THE RX-8!!!
Okay, if I've read correctly, floor the accelerator to cut off fuel when you starts the car, so, for those who wanna move their car just out of the garage to wash, they should practise this procedure. Right? Is it as simple as this?
So for that matter, anyone who's not gonna drive the car long enough to warm up the engine should practise the accelerator start rather than the clutch starts.
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Old Dec 19, 2003 | 08:32 AM
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Originally posted by M-ster
HEY GUYS, ARE WE SAYING WE CAN FOREVER AVOID FLOODING THE RX-8!!!
Okay, if I've read correctly, floor the accelerator to cut off fuel when you starts the car, so, for those who wanna move their car just out of the garage to wash, they should practise this procedure. Right? Is it as simple as this?
So for that matter, anyone who's not gonna drive the car long enough to warm up the engine should practise the accelerator start rather than the clutch starts.
NO NO NO

The de-choke procedure is to clear a flooded motor, not to avoid one.
Only use it after you have determined that you have flooded your motor.
The proper thing to do all the time is the rev-up to stop.
Right before you turn the key, gently run the motor up to 3500 RPM and then let of the pedal exactly as you turn the key off so that it runs down while the fuel delivery and spark cut are off.
That way it won't flood in the first place.
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Old Dec 19, 2003 | 01:39 PM
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Also, I checked last night and you could wire in a fuel pump shut-off switch. The ECU shouldn't throw a code. The fuel pump system looks very similar to the 2nd and 3rd gen RX-7s (two stage pump speed).

Rotarygod, your 2nd gen should have the system. I think on those models it was a switch on the floor under the accellerator. At least that is what I was told by other owners.
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Old Dec 19, 2003 | 02:34 PM
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Originally posted by jtimbck2
If you flood the engine, you're supposed to crank it for 10 seconds with the accelerator floored, then crank normally. I had to repeat this a few times when I flooded mine, but it did work eventually.
Where is this in the owners manual... I swear to god there is nothing that mentions cold starts yet alone flooded starts in my manual
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Old Dec 19, 2003 | 08:45 PM
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Originally posted by pr0ber
Where is this in the owners manual... I swear to god there is nothing that mentions cold starts yet alone flooded starts in my manual
Page 7-20 in the manual - Starting a Flooded Engine
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Old Dec 20, 2003 | 06:18 PM
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Originally posted by Jag
Page 7-20 in the manual - Starting a Flooded Engine
thanks, I'll check that out
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