vems duty cycle,max hight?

[quattro-nick]

yesterday i was tuning vems on the road
i have a gt3076r and siemens deka 630cc with 3.0bar fuelpressure and 044 bosch pump
I've noticed that when I drive with full throttle under full boost(2.2bar) at higher rpm my duty cycle on vems go over the 100 % like 108%
is that bad and does this means that the injector cant follow?
i have a adjustable fuelpressure regulator so i can set my pressure on 4-5 bar or maybe is the flow of my pump not enough?
I am afraid that the mixture will be too lean at higher rpm and thats not good for the engine
or should I completely do not worry?

[prj]

100% is 100%.

100% means the injector is open 100% of the time. It never closes.
Any number over 100% means that the injectors can not supply as much fuel as the ECU is requesting.

Whether that is due to dropping fuel pressure or not enough injector flow is a different question. Need a fuel pressure gauge and some WOT runs.

If you are getting this much duty cycle in summer, then in winter with colder intake temps you probably will melt your engine.

[popdemonic]

you need 4bar FPR.what fuel you are running?
if you are running on E85,your injectors are
maxed out with that level of boost.i have GT2871
with same injectors on 5bar FPR.Inj DC is somewhere
like 95% now.

[A80Avant]

Yes. You need to adjust the for to 4 bar or 3.8 that audi has. That should be plenty for the dekas to cope.

[a4kquattro]

as others have mentioned, 100% is bad. it means no more fuel can be injected. We try to target no more than 80% duty cycle when possible when sizing injectors.

upping your fuel pressure to 4bar will help.

[quattro-nick]

thanks for reply guy's
i drive with pumpgas 98' octane
i will set my fuelpressure on 4 bar but that means also i must completely adapt my ve- table in vems
tomorrow I go back on the road with 4 bar fuel pressure

[A80Avant]

Yes unfortunately tou have to do that. Hopefully it may be just adjusting the whole map slightly lower.

[prj]

Uhm, just change req. fuel why would you move the entire table?

[Rocco]

Your wife must be very bored those weekends...

[Bowie69]

Uhm, just change req. fuel why would you move the entire table?

Exactly

[quattro-nick]

have not thought about reqfuel, thanks for the hint prj
i think it stands now on 3.0 (reqfuel)
Tomorrow I will try with 2.8 or so and see what engine and lambda doing on idle

[jade]

3.8 ?

[A80Avant]

ADU original

[jade]

Tomorrow I will try with 2.8 or so and see what engine and lambda doing on idle[/QUOTE]

I was commenting on this, Thinking he was referring to fuel pressure

[quattro-nick]

sorry,i mean 2.8 reqfuel
i have made a change on post 11