It has been suggested that the rotary engine is proned to flooding if started and then turned off immediately ie to move the car a few metres. Apparently once started the engine needs to be warmed up/ run for at least 5 minutes otherwise the very rich mixture which is initially injected will flood the engine.

Any rotorheads wish to confirm this.

rael.t

Can't confirm the principle for rotary engines, but it happens the same on my V6 Audi! Not aware of any problems with my car, and fuel consumption is fine. Probably a few conventional engines prone to that.

JH

Aparently rose on older engines, and engines with more miles on.

But there is a story about an RX-8 with 3.5k on which was flooded and after 3 days had to be trailered to a dealer for fixing.

There is a startup/ short run/ shutdown procedure in the manual, it does say font start then stop soon after. (5min idle, 20sec 3k rpm , switchoff or something).

New ECU/cat etc make it more difficult to do on renasis than 13b etc.

Whilst it does happen on piston engines, there much quicker to get going again - or so I hear, rotary virging here.

My RX-7 has flooded on two occaisions, both times I had to have it recovered. So as not too make people paranoid I must point out that the engine is on its last legs or rotors even (64K miles).

All they do to get it running again is tow/bump start it.

It has never flooded by being run for a short period of time, which I know should not be done but hell the engines on the way out anyway. It was cold weather which added to my problems.

You consider 64k miles 'on the way out'?
:O

Originally posted by ROTORIST
My RX-7 has flooded on two occaisions, both times I had to have it recovered. So as not too make people paranoid I must point out that the engine is on its last legs or rotors even (64K miles).

All they do to get it running again is tow/bump start it.

It has never flooded by being run for a short period of time, which I know should not be done but hell the engines on the way out anyway. It was cold weather which added to my problems.

On it's last legs after 64k!!!:eek:

I hope this isn't the expected life of a rotary engine as I nearly do that in 2 years - I'd expect at least 3 times that mileage from a new engine. Please tell me that the RENESIS isn't a sub <100k miles engine. :(

Dont worry andy, heard the rotor tips are good for at least 150k miles, as stated by mazda I think.

RobDickson is correct the renesis is apparantley far more durable than previous rotary engines!

Mazda would have been mad not to ensure that this was the case espacially with the volume they are producing.

RobDickson,

Both times it was recovered they ran a compression test and it was very low, it was given a life expectancy of between 600-6000 miles more before complete failure!

The sooner the better as I still have a warranty!!!

If I ever move my Mazda Xedos V6 out of the drive to let my wife out and turn off straight away, it is guaranteed to flood every time.

If I let it tick over for 30 seconds before turning off it's fine.

So this is not just a rotary problem.

My old RX7 only flooded a couple of times.
Only once did I have to remove the plugs , dry them off and start over. But that was running a manual carb setup , not a whizzy computer controlled fuelling system like Renesis.

In my experience rotaries do need more cranking over than a conventional engine , so dont expect it to start immediately - it may take a few seconds of cranking....

As for that 64K miles. What the hell ??? That must be one abused engine. You have nothing to worry about with durability.

I've never had this problem with a piston and it's something I've done fairly regularly where I start the car and stop it again (usually because we need something for one of the kids before we leave!)

... and I never bothered about it on my old one either.
Dont expect it to be a real issue.

morganrogers,

No, it has not been overly abused, 3rd generation RX-7 engines have a life expectancy of 60-70k, what generation was yours?

My 2d gen RX7 has 215k on it, and I'm beginning to have some hesitation near the redline, so I think the aux ports have become a little clogged. Otherwise it's still been happy motoring!

Ah ! 1st Gen NA (not turbo).

I think we have the answer....

It popped yesterday!

Bugger!

Was your warranty still in place?

Cheers, yeh 3 months to run, so fingers crossed that all goes smoothly!

I should now be referred to as rotorless!!

ROTORLESS :(

What happened - did it just give up the ghost or was its failure more spectacular? I'm around 38k miles but with my annual mileage, the rotors should still be going in 10 years time.

My 3rd gen has flooded a few times when its been moved a short way, but never had to have it recovered, just wait a while.

Anyway, sorry to hear there's 1 less on the road and hope your warranty holds good.

97rsr

I was about to over take on a long staright, 4th to 3rd (my favourite gear), power down edged out and it went "POP", so back in and rolled down the hill to the nearest lay by, well nearly.

Was kept amused while I waited for recovery by some nut in a TVR 350i hammering up and down at some pace, he obviously liked this road too or maybee it was a first for him seeing a Jap car failed instead!

Sounds like you have afew years left in yours enjoy it.

From the following thread:
http://www.rx8club.com/showthread.php?s=&threadid=12126&perpage=15&pagenumber=2
I just got my car back from the dealer. They had it for 3 days. Tried to start the car, sounded like it was flooded. Called roadstide assistance and got the car towed. The tow truck driver said "Funny, this is a third one of these I've towed", then "Don't worry, Mazda can fix it" I call the dealer, he is like "you flooded it, and your the ninth person we have in here since we started selling them".


Looks like it is still a problem with the Renesis then :(.

I'm sure I can remember not to start the engine and then almost immediately switch it off again. My real worry would be if I accidentally stall it immediately after cold starting.

It seems that a loose battery connection can cause the problem too: it can't quite turn it enough to start, but it still pumps plenty of cold fuel into the chamber

Theres an anti-flood routine built in, dunno if anyone knows/uses it though.

Originally posted by RobDickinson
Theres an anti-flood routine built in, dunno if anyone knows/uses it though.
Apparently, if you turn the engine over with the throtle fully depressed, then it should cut off the fuel completely. Do this for a few seconds and then turnover normally (no throttle) and it should start.

Unfortunately, no one seems to have had any luck following this procedure yet. However, one person has successfully started his flooded RX-8 by turning over with the fuel pump fuse removed, then normally, which should amount to the same thing. The procedure may need to be repeated several times.

Once the car does start it briefly produces large quantities of thick, black smoke, so if you do this regularly you will not be popular with your neighbours.

ROTORIST

Agree about 3rd, though 2nd isn't bad either :D

Originally posted by ChrisW
Looks like it is still a problem with the Renesis then :(.

Well at least we're not getting our cars at the start of a British winter or anything so it shouldn't be too bad... ;)

my previous Rx 7 TurboII had 11000 miles on it and was running perfectly when i sold it. I would still expect it to be running today. All my Rxs had done in excess of 100,000 Miles on original engines WITHOUT any maintenance issues.... and remember, theres NO Valves, Cam Belts etc to worry about.

Golden rule, as with any vehicle, let it warm up before exploring the upper rev bands. In my case i keep revs between 2-3000 until gauge has been in normal postion for at least a few minutes. Incidently, this i apply to any vehicle i drive. Alfas are/where especially sensitive to warm ups!.

Flooding was/is a main problem with the FBs, the S4 FCs, and -very rarely- the S5 FCs (latest version of FC). I have heard of VERY few FDs that have been flooded. This is a problem with the ECU and the injectors "dripping" fuel after starting up the engine and shutting it off while still cold and in the warm-up phase of the ECU program and the thermowax position. (if you dont understand what I've just said, I can explain in more details ;) )

This is NOT a problem only for RX7s or rotaries. This can happen to ANY car, if there isnt a failsafe built-in in the ECU or the mechanism for the warm-up cycle. So, the fact that it happens with RX8s doesnt mean all that much.......

Anyway, the way to unflood a rotary is pretty easy: once you know you've flooded the engine, you can try the "gas-pedal-to-the-metal" while cranking (which works only 20-30% of the time), or you can go for the "real" fix. Pop hood, remove EFI fuse, take off lower spark plugs and plus (if you have the proper ratchet, and I do mean PROPER ;) ), and crank engine for 10 seconds. That should get rid of the fuel in the engine. If the plugs are fouled, clean them/burn them with a lighter, and place everything back. Crank up the engine, and it should start. However, if the plugs are totally fouled (i.e short-circuited) you have no other choice but to call for road assistance.

The above has happened to me once, due to a stuck AFM. Flooded the engine REALLY good :o Plugs were just little pieces of metal and ceramic. Tried unflooding, tried cleaning the plugs, nothing. For a moment I thought that I may have actually popped the engine. However doing the manual/ghetto compression test, I saw that the engine did still have good compression. So, 4 spark plugs later, engine was purring like a cat...... ;)

Originally posted by The Ace
This is NOT a problem only for RX7s or rotaries. This can happen to ANY car, if there isnt a failsafe built-in in the ECU or the mechanism for the warm-up cycle. So, the fact that it happens with RX8s doesnt mean all that much.......
You may be technically correct that this can happen to any car, but in 15 years, with a variety of cars, it has never happened to me.

The number of reports we have of people in the US flooding their RX-8s, and the fact there is a specific section about this in the user manual (the "short trip driving procedure") seems to indicate that this is a much bigger issue than with most other cars.

It's a more serious issue with rotaries than with boingers because the fuel can't drain off by itself.

I don't know, it seems the more I read about this engine the less I like. I mean, in this day and age, having to remove fuses or pull plugs to unflood it. That's almost pre-historic.

Apparently these engine still have a long way to go before they're as useable as the piston engine. All they've really got going for them at the moment is size and number of moving parts. Good though those things are, in all honesty I think the average driver would put those well down his/her list of desirable features.

C.

Originally posted by ep3
I don't know, it seems the more I read about this engine the less I like. I mean, in this day and age, having to remove fuses or pull plugs to unflood it. That's almost pre-historic.

Apparently these engine still have a long way to go before they're as useable as the piston engine. All they've really got going for them at the moment is size and number of moving parts. Good though those things are, in all honesty I think the average driver would put those well down his/her list of desirable features.

C.

No they wouldnt. Which is why thee not used in average cars. Only 'sports cars' mostly. small,light and high power are traits which are very usefull.

As to being "pre-historic" yeah, thats close. Piston engine was invented a long time ago (100+ years) and since day 1 has had a lot of R&D done on it, every day thres proabbly 1000's of engineers working on small advancments on piston engines all over the planet.

The rotary has had a minute fraction of this development work. Mazda has had anywhere from 80 to 2 people working on wankels. They have benifited from modern production and materials/technology but are way behind pistons in terms of development. I'd say late 70's early 80's equivelant.

And despite that there still very competative and won international engine of the year award. Mechanicaly, theoreticaly (and by some perameters reality) there superior to pistons. I like smart engineering solutions, and the wankel engine design is an amazing change over pistons, its "how it should be" IMO. Getting it to work in practice isnt always easy.

Rob,

Wouldn't agree with you on "high power" being a trait of rotaries over pistons necessarily. You can't really compare the power of rotors versus pistons based on enigne size because the displacements are used very differently. If you compared power (or energy really) per litre of fuel used (which is independent of displacement) then I'm sure you'd probably find pistons winning again (discuss).

I agree with the rest of your argument (sort of). However, what I do object to is that the average man in the street could easily be won over by (forgive me) "rotary hype" without being presented with real facts. To me it seems as though Mazda are using a relatively gullible public to act as a test bed for their technology. Sort of "...let see if we can get them to buy a rotary, then we'll actually develop it properly...", or, maybe it was a case of "...we've invested so much money in this engine there's no way we're gonna ditch it no matter how gopod/bad it is..."

Maybe that's over cynical, but you get my point...if you're gonna do it do it right or don't do it at all.

C.

They are doing it right. What are they supposed to do, never sell a rotary because its always behind pistons from a research point of view?

You cant develop without funds, you think piston engines arent a testbeds for tech? this engine has been tested in mazdas research labs as much as any piston engine, but thats never going to replace 1000000's of man hours of research.

As to high power, I'm talking power to engine size. nothing competes there (NA anyhow).

Rob,

OK power to engine volume (for standard production casrs), rotors win over pistons.

But if you're gonna compete with pistons then you either have to offer something radically different in terms of the everyday driving experince (it's not, it's just a flat torque high rpm engine with a slightly diferent engine note and smaller flywheel effect, same as an alloy vtec), or, you've got to beat the piston at it's own game (which it hasn't in almost every way but size and number of parts).

C.

Originally posted by ep3
But if you're gonna compete with pistons then you either have to offer something radically different in terms of the everyday driving experince (it's not, it's just a flat torque high rpm engine with a slightly diferent engine note and smaller flywheel effect, same as an alloy vtec)
Have you driven one? I think "radically different" is a good description of the Renesis at high revs - much smoother and more progressive than a Honda VTEC.

The comparison with the piston engines is all very interesting. Still, sorry for writing about the original thread here....!

A cousin of mine is a researcher in the field of vehicle emissions. From what I undersatnd, under the forthcoming emissions regulations (Euro 4), an engine must reach its quoted/allowed emissions figures within less than a minute (20 secs I think). Please correct me if I am worng

The engine, cataliser, etc, are all designed to do their clean-up act under high temperatures, and so need to be warmed up PDQ after the engine starts. This is achieved by flooding the engine, essentially causing burning flames to spread around the inside of engine and the exhaust system.

ep3... sonds like u have not driven a rotary. There IS NO WAY i would compare our Vtech to our FD Rotary, or even the FC Rx7 TII. The Vtech feels rough, clunky and kinda agricultural.

Comparing the rotary to a VTEC engine is not so crazy. They both have similar power output graphs (only for HP, rotary has much more smoother torque curve), and they both shine at high revs, where ALL other engines have stopped working ;)
However, the way these engines achieve this performance is totally different, and of course they are also completely different engines to begin with.....However, I dont think a VTEC is "agricultural", if anything its a very nice sounding engine. Of course, the rotary is in every case much more smooth and with a very unique sound......

As for the emissions stuff, thats what the pre-cat is there for. We may finally see the pre-cat being in actual use, because up until now it was only an obstruction......

Good news story regards my blown RX-7!

Upon inspection both of the rotors/housings were shot resulting in turbos to also be ruined. (Rare for both rotors to go apparentley).

The warranty company have come up trumps, my dealership had instruction yesterday to go ahead with a reconditioned engine, new turbos and a new wiring harness (they will also fit a new clutch while it's out at my expense).

Relieved and happy! :)

The Cyclone V8 has a higher power-to-size ratio than a tuned Renesis.

http://www.cyclonepowerltd.co.uk