Lock & Load

THIS THEORY ON THE FLOODING ISSUE has been put forward by FORUM MEMBER TRZ750 INTERESTING ????


Reving is a waste! The problem was a missed setting by Mazda on the engine and air temp sensors. When in cold weather the engine was started and shut off after only a short time the hot water would rise to the temp sender and the ECU would think the engine was warm, when it really wasn't. Then also in clod weather after sitting for a hour in the hot sun, the air temp sender would register higher temp than real. The ECU probably wasn't properly programed and defaulted to a rich condition, or at times the reverse and too lean. I had both these probelms before the M flash. My wife mostly the sitting for an hour when shopping (on a sunny, but cold January day). Each time I (or told the wife) to turn the key off, put your foot all the way down to the floor, and crank until it starts. Each time it started after about 5~10 seconds. Full throttle will both add more air to help clean out a flood engine and cause the ECU to go to a default setting.

Now with the M flash the problem is resolved in the ECU. By the way this is not a "Rotary" problem, but a EFI problem that could happen on any new car.

cheers
michael

AMG

Michael, I might like to point out that my flooding problem occured after I had the most recent flash upgrade (G), which the dealership informed me at the time was designed to, amongst other things, address the flooding problem.

Gomez

Yeah, it's a theory on why "some" cars flood.....Yours and BVD's flooded under different circumstances, obviously.....

Hymee

iTrader: (1)

If the ECU thought the engine was hot when it was cold (per theory) then it would go lean. Lean <> Flood.

Yawn.

CCX

Here is the chance to "bag" the hell out of a new member who doesn't have much technical expertise.

I have reading the threads about flooding and I have noticed the following 3 things.
1. Won't start after stall
2. Won't start after left for long period
3. No return line to tank

Has anyone considered that it is a "stopping" issue rather than a "starting" one. If there is no return line to the tank does that mean that the fuel line remains pressurised and that this causes fuel to "leak" into the cylinders when the engine stops or is left for long periods. If it is a valve that restricts the flow then could it be that either fuel contanimates or higher pressure in the fuel line cause the value not to close correctly. If so would adding something that, on engine stop, allows the pressure to drop to zero but keep the fuel line full help ?

I await you "bagging"

regards
CC

Gomez

Gee, see what you blokes have done.....everyone is gun-shy now!!.....Yeah, CCX, that was a theory of mine......The trouble is that it is difficult to get any info out of Mazda about this problem. Others, both here and in the States, have tried though.

The fuel regulator in located inside the tank and is a non serviceable sub assembly of the fuel pump/filter unit.....If there's a problem there, then the lot gets replaced at megabucks a pop.
It may be an intermittent problem with the unit, we don't seem to have too many occurences of this problem here in Australia.

Mazda North America identified a problem with the injector pulse width during cold start-up and released the "M" flash which has effectively cured the problem there. A few of the members here though have had their cars start, then stall, and refuse to restart. In mild temperatures...

It's more than one problem, methinks....

Gomez.

Lock & Load

GOMEZ

The RX8 has no problems only CHALLENGES .

I have decided to take a more positive attitude to the challenges .ha ha ha

cheers
michael

Gomez

Baaahahahaha!!!

BVD

Interesting theories all round...

I does seem, as CCX and Gomez have suggested that there is definitely some electronic and/or mechanical thing going on there that allows the engine to flood.

The service manager who fixed my car seemed to think that the failure/difficulty with restarting was pretty much down to the platinum plugs being very easy to foul with fuel, and not easy to dry out without removal.

Which leaves the question of why it floods in the first place, and why it seems so tantalising intermittent. It seems pretty clear that you can do exactly the same things on many occasions and get away with it, and then one day the Gremlins decide that now is the time to have some fun with you and.....phut....

To me, this suggests that you need 2 things:

1) That the car is stopped, either accidentally or deliberately, at a time when the car is getting maximum doses of rich fuel mixture. The car needs to be cold, and it seems more prevalent if the weather's fairly cold too.

2) That the engine stops at a critical stage in its rotation, leaving something either unhelpfully open (or shut) or at a particular stage in delivery, or at a point where it might leak, or whatever. Lots of possibilties and I don't know the engine well enough to make a best guess.

Some people have also suggested that the battery is a bit weak for the car too, and certainly cold weather, unre-charged drain from a recent start, or having left the car for a while, might all make it harder for the battery to fire up a flooded car.

Whatever....

Since the problem I've certainly been taking a lot of care to make sure the car is never stopped when it's cold. Interesting to see a big difference in the start pattern with the G flash too. It used to start and rev at 2,500 for a while and then drop back to 1,000. Now it's starting at 1,500 and dropping back to a bit under 1,000rpm.

Despite being somewhat cheesed off by the timing of the suggestion at the time, Taka's comment that we should all just warm the car up for longer before moving seems hard to pass up! :D

Gomez

That's interesting....My "F" flash idles at around 850 when warm, I'll double check later. BVD, did your car idle at 1000rpm when up to operating temp prior to the flash?

sco

Mine idles about 800 both prior and after G flash

BVD

Gomez,

Yes, it did seem to idle faster when warmed up than it does now.

But of course, as Hymee said in another thread, you can't swap back to the old flash to double check and see whether some of your perceptions and memories were as accurate as you'd like to believe. :D

My car is a July 03 build and had no other flashes between new and the G.

It alway seemed "high revving" on idle to me, but I'd put this down to being a feature of rotary engines. As there is a mechanical reduction of 3:1 between the crankshaft speed and the actual rotors, I'd just assumed that the crankshaft was doing 1000 rpm, but the rotors only 333rpm - which is a relatively gentle tickover.

Of course there's bound to be differences in idle speed between individual cars. And my interpretation of what the rev counter is actually reporting might be totally wrong anyway! I'm a self confessed rotary newbie. :D

BVD

BTW,

If anybody wants to read Mazda's current position on this, Rosenthal Mazda in the US has a site with the official service bulletins posted.

http://www.finishlineperformance.com...ocs/index.html

Some handy info in the bulletins.

Most are a quick load, but the Engine cranks/No start one is a 354k pdf file (needs Acrobat Reader) with 12 pages, so takes a while to get.

CAUTION:

Apparently Australian dealers don't necessarily get the same bulletins as the US, and seem to get them later if they do. In theory at least, our cars may not get some of the problems seen in the US. In theory...

Gomez

Just checked, idles around 800/850rpm....

Hymee

iTrader: (1)

Mine cold start idles at ~2000+ RPM and slowley slows down. After 10 or 15 seconds (not accurately measured) the revs drop back a by a fair jump, but then recovers to a normal fast idle. When warm it idles at about the 850 mark, give or take.

I wonder if I try to stall it during that small window of time when the revs drop if I might replicate the problem??

Cheers,
Hymee.

AMG

My series 7 RX-7 starts up at around 2500+ RPM and dies down to around 800RPM after 30+ secs. When bought the car it was stresses on me that in order to look after the turbos the warm up cycle must occur uninterupted. The was no discussion on flooding.

The platinum plug theory is interesting. My ex-race car had platinum tipped plugs and at one stage when the fuel mixture ran rich they were fouling all the time affecting the smooth running of the engine. One day I had to change three sets of plugs,my mechanic told me until he restified the problem to keep the revs above the 2000RPM mark. What this means I don't know,I just pull teeth for a living.

Hymee

iTrader: (1)

As long as you don't pull legs. LOL

AMG

Hymee, if that is an attempt at humour then stick to your day job

LOL!

BVD

Interesting idea.

You might be onto something there, even if you don't manage to reproduce the problem. That odd little fall and surge may represent some sort of change of mixture state that could tie in with a vulnerable time? I wonder what it's all about??

I just went for a drive on what's a fairly cold wet night here, and on starting it revved higher than it had on the previous daytime start.

This time it started at a whisker under 2000rpm and shortly after did that odd drop and surge thing you mentioned. Then it settled down at around 1500 before slowly dropping back to 800/850 or so.

What a beautiful drive too. It's been thrashing down with rain here so the roads were soaking wet and almost deserted. I was able to keep the window fully open without getting wet, even when it came down hard. The feeling of speed was heightened by the dark and the rain, and together with the surefootedness of the car, the glistening road, and the exhaust note singing through the wet trees - what a joy! :D

I have forgiven the car its little quirks - it really does deliver a delightful driving experience....

Hymee

iTrader: (1)

Nice post BVD.

I wish we had some sort of system whereby we all could award a rating to people's posts. Then we could all aspire to a rating wich reflected something meaningful, rather then the total post count.

Cheers,
Hymee.