inboost

Sniper X,

This is what I've been hinting at by posting the message in the first place. I will probably be looking into this more when I have some spare time with an o-scope...

Sniper_X

I know its not in the map.

Its IMPOSSIBLE.

itf it were in the map, it would happen every time WOT was experienced.

Its in the ECU firmware, possibly tied to a delay circuit.

Icemark

No, not impossible,

Again it receives the starter signal as well as TPS. It would be very easy to see both as short or long signals. A concurrent long signal on both, disables fuel injection. (which would explain why some people must still add the fuel kill switch- leaky injectors).

But a long signal only on one has no affect.

Sniper_X

So your implying that with the engine running, if I hit the starter, cLutch in, and then wen to WOT, it would kill the car cause the injectors are killed?

Easy enough to test.

Icemark

No! I was suggesting the engine not running.

Your test might work, but if I am correct; its only gonna kill the injectors while cranking and at WOT. You would need to disconect the starter At the starter not in the dash since the ECU gets its signal from the starter kill relay but I am not sure how you will prevent overrev with the clutch in and the engine already running.

Again following if I am correct, you will need to crank and be at WOT for at least 2 seconds.

Vroomaster

"Therefore, there is NO, and I mean -NO- need for fuel cutoff switch as I have always thought."

Not for starting, but for safety, it's best.

Sniper_X

"Not for starting, but for safety, it's best."

How is that safer?
Its not gonna prevent a fire.

Scott 89t2

I've never had to try

inboost

The fuel map approach isn't out of the question as long as the two axis on the map are TPS and RPM. Then you just set the upper left-hand corner to zero some RPM amount below the idle RPM. Then you only create a non-fueling load site below idle and at WOT. As soon as the engine starts it RPM's past the idle speed and your normal mapping takes over. You would never get back to that load site unless you stalled the car with your foot all the way to the floor (a pretty unlikely event).

This is undoubtedly NOT the case for the RX-7, I would expect it to be mapped 'air flow meter' vs. RPM or 'manifold pressure' vs. RPM (maybe even both, like a secondary load table). So your argument that it's not on the main map still stands.

My curiousity stems from how this routine 'ends', as we all know now that all we have to do is 'stomp & start' the next time our cars are flooded. But when does the injector turn back on? Can we call this routine up any time the engine is at zero and the TPS is at 100%? Is there a temperature restriction? A time restriction? Once we know the answers to these questions we can answer the "Do I really need a fuel cut switch, or not?" question with some authority.

Thanks for everyone's constructive feedback, I appreciate it!

RexRyder

iTrader: (10)

If the switch is hidden and off, and someone tries to steal the car (ie: hotwire) they cant, cuz no fuel is getting pumped (duh). then again any car could be stolen with a tow truck or trailer.

Sniper_X

AHHHH anti-theft...
I see.


As far as the idea of it not being mapped, it it was mapped, then how come once you let off the pedal during a WOT start, you cant floor it to kill the injectors again.

Its a one time deal, once you let off the pedal, the injector kill routine is over.

inboost

This is what I intend to find out! If the routine is too restrictive then the car will end up with a fuel cut switch instead. Actually, I hope to find some other cause for the flooding on the particular car I'm going to be working on. It may be one of the many mechanical reasons for flooding on start that's going on. If so, all the pedal stomping in the world may not stop it from failing to start (a leaky injector leaks regardless of the ECU's decision to turn it off).

Aaron Cake

iTrader: (1)

Not all 2nd gens have this feature, ONLY the S5 cars.

Why? Because the S4 TPS only reads to about 1/4 throttle, so the car has no idea that the pedal is floored.

The reason flooring an S4 car works is because it allows lots more air into the engine, thus helping to clear out the excess fuel.

Icemark

well doesn't that throw a wrench into the debate

eViLRotor

iTrader: (2)

Heh! Aaron knows too much for his own good...
I'm at least a lifetime of knowledge behind, lol....

Sniper_X

I knew this too!

However there are people there that have posted PICTURES of S4 cars WOT procedure.

I just KNEW S4 cars couldnt do this. (becuase of the TPS)

So whats the deal with you S4 guys saying its possible?

If so then how is the S4 ECU determining WOT?

Icemark

I think you are missing the original idea to this thread, it was:and you also said:
But there is also a procedure for all fuel injected 13Bs, not just series 5. Then we went off on a tangent trying to figure out how it works. If there is a procedure, then why are you having problems with it beeing possible on series 4 cars???

fdracer

is there a permanent solution to prevent flooding in the first place?

Sniper_X

I certainly DONT have a problem with it.

I just disputed that there was a WOT start procedure at all on S4 cars.

If there is one, then how is that possible?
Every bit of information until today stated that there was not.


well of course there is...

Either:
a) The injectors are not closing on these cars.
b) A sensor is stuck sensing COLD or similar situation

Most of the time its the injectors.
Rebuild the injectors, voila.. no flooding.

Now I know that there are people that have rebuilt the injectors and continued flooding.

Even though the sensors checked out good.

It would them be time to pull the injectors and place them on a test bench to see if they leak under pressure.
then test to see if they are just slow to close by firing them at various duty cycles and then seeing if the close off after that.

I bet these people have slow closing injectors.

inboost

There are other good reasons for flooding from what I can see on an S5 car. Obviously if any of the following systems are on the S4 then you've got equal potential for trouble:

1) The ECU deliberately raises the fuel pressure by cutting vacuum to the fuel pressure regulator with the "PRC" solenoid pg F2-54. Unfortunately the english is very poor here leaving me wondering exactly what it is doing. However, if I interpret the following phrase correctly:

"Specified operationn time: For above 50 sec. after cranking (ET>65C, AT>60C)"

Then I would say that when a hot engine is first started, the vacuum signal to the pressure regulator is cut for 50 seconds. During this time the fuel rail pressure raises and therefore any given pulse-width sent to an injector will deliver more fuel. Perhaps this is too coupled with cranking enrichment and any other trims active at the time of hot start.

Older cars with leaky injectors would be effcted more. The injector bleeding fuel into the combustion chamber is what causes the problem, the additional amount of fuel delivered under PRC active makes it worse.

2) I would suspect that when the fuel pump is stepped up to 12vdc that the rail pressure has the potential for being higher. The Pressure regulator would hopefully correct for this, but I suspect that the ECU simply cuts back on injector on-time when the car changes from low to high fuel pump pressure at any given point. If I am correct, that means that anyone who is running the fuel pump on 12v all the time is rich at part throttle and idle. This additional pressure at cranking effectively emulate the PRC issue described in point #1

The only thing to be said here is that both of my points would tend to aggravate a hot start more than a cold start. If the flooding condition is occuring regardless of temperature then I would vote for pulling the injectors and watching for leakers. Of course any device that should be providing more air at cranking (BAC, AWS,ASV) which is not functioning could also cause trouble. The engine may not start because it is too rich and then at restart we only make the problem worse. Opening the throttle adds the additional air which these devices fail to add and perhaps allow a start.

Just thinking out loud...

Icemark

Sorry, I guess that since there is a WOT start procedure in the factory owners manual since '84 for flooding, I can't agree with you on

Sniper_X

Okay, but you do know that Aaron mantioned that the TPS cant be part of this WOT start procedure.

Also, S4 cars on the forum all talk about fuses, pushing, ATF, etc to start them, but the S5 owners here mostly know that WOT start is the way to unflood.

So, i am shocked to see it in the FOM and the like.

this is the first i heard of it.

So..

How does an S4 KNOW ABOUT WOT START? !

inboost

I'm willing to bet that the S4 car doesn't actively make any WOT correction for flooded start. It's just no different than starting a carb motor at WOT. If the seals arn't washed out too badly (i.e. the system fuel pressure didn't bleed down completely into the rotor housing) then the car has enough residual sealing ability on at least two apex seals / sets of side seals that we get a combustion event on at least one face and the others purge into the exhaust. Probably good for some flames on some of these exhaust systems I've been reading about!

Icemark

Based on Arrons input, I tend to agree with you inboost on that assumption for the series 4 cars.

The extra air from the throttle plates being at WOT probably helps wash out the unburned gas. That would match up with the non-pumping of the pedal requirement, which if not followed would dump more gas in with each pump of the pedal.

so based on that both series have a method of starting when flooded, just on the series 5 and 6 its controlled by the ECU.

inboost

Sounds like a good conclusion to me Icemark.