I'm designing an aftermarket injector controller and at WOT = Wide open
throttle, pedal to the floor, the vehicle that the prototype box is
installed in, is getting a warning from the software that injector
dutycycle is 100% above 4000rpm/WOT. In other words, system running
out of injectortime. My question is generally, if there are any
problems for injectors coming into continous operation, (100% duty
cycle), like overheat etc etc?
Of course the 100% duty cycle applies only to a few seconds or so.
On 31 Jul 2006 20:59:22 -0700, email@example.com wrote:
Educated Guess Time: For a few seconds at a time it shouldn't hurt
anything. I would be more worried about running it that hard because
if it needs even more fuel and you "ain't got no more", you could
start running lean. And too lean at WOT could start eating valves or
doing other nasty things.
Why you are triggering the warning in the first place - do you have
any control of the fuel pressure regulator? Or can you stick a VSV on
the fuel pressure controller line to trick it into going higher on
command? Pump up the injector rail pressure, and you can drop the
duty cycle on the injectors a proportional amount and keep the mixture
where you need it, and then you won't be flirting with a lean
--<< Bruce >>--
You and I have gone through this before.... when you talk about 100% duty
cycle, do you mean the injector is on all the time? This could present a
problem during compression power and exhaust strokes, right?
FWIW... and of course YOU are right and I am wrong.... Injectors are NOT
duty cycled.... They open once per stroke cycle and are left open for a
perscribed period of time decided by the PCM. Then, amazingly, they close
for three full strokes....
Factoid.... Ford does not list injector duty cycle in ANY of their current
service literature. Grasping an example, the Mustang GT500 lists max
injector on time as less than 10 ms.... Years ago, I already did the math to
find out how far the piston travels at various rpms in regards to spark line
time... typically about 1.5 ms, much less than 10ms. Over to you to figure
out how far the piston will travel in 10ms at say 4000 rpm...
Trying to apply duty cycle computations to a changing frequency must be
somewhat frustrating.... especially when we consider that stock fuel
injectors live quite well at WOT and even better when we consider mechanical
limitations.... like, leaving the injector open all the time is going to
leave you with puddles of fuel sitting behind the intake valve waiting to
send your mixture pig rich and your power curve in the toilet...
Feel free to comment on my "mistaken" ideas.... I'm not the one that can't
make this thing work... Mostly because I have no misconcneptions about
applying duty cycle to an event that needs to PWM...
If you are running out of injector "on" time, is there a chance that you
need to make a change to injector flow? If you are writing a program that
adjusts the fuel curve, simply adding more "on" time may not cut the
mustard. There is a need to understand the events that occur both in the
intake tract as well as the combustion chamber.
To some extent, brake mean specific horsepower computations performed
through dyno testing have been replaced by mass fuel desired computations
that the PCM applies to fuel delivery. Simpy adding fuel to the point that
the injector has no more "on" time isn't going to accomplish much other than
to make someone, eventually, realize that fuel will precipitate out of the
intake charge and stratification is likely going to happen along with it....
Let's face it... the guy is either totally off his nut or he's researching
for a different application.
Since he insists on the 100% duty cycle, I suspect it's as a continuous
valve/injection source, like a furnace burner or turbine etc
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
I appreciate your input, and respect your knowledge, no doubt, but it
seems like you didn't exactly understand my question, or maybe didn't
read it properly.
Anyway, I lower my sight and try once more:
Is there any possibillity for a high-impedance (voltage driven)
fuel-injector to get damaged of continous operation. That means on all
of the time (didn't say 100% duty-cycle...) for a couple of seconds?
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