Injector Duty cycle 142% ???

[NJ_Phil]

So I got this guy with a built out CTSV running close to 18 psi, who asked me to look into his tune and first thing is to look is scan a few pulls and noticed his Injector duty cycle is close to 150%.
Told him no way I was touching the car until I put new injectors in and he said his tuner said the Duty cycle shown in HPT isn't real and his tuner just ignores the reading.

He wasn't sure what injectors he had it, thinks 85lbs and basically told him to come back when he was ready for new injectors.

Question is how come the motor is still in 1 piece running at 140+% with no sign of knock and no sign of leanout on the narrowband sensors (> 900mv). Knock settings are stock in the tune.
I mean this guy pushes this thing hard, shifting at 7400, 18psi and deep in the 10s running 1/4 mile all the while with injectors running over 28ms pulse width.

[5FDP]

Is it an earlier computer that has a max of 63.5lb/hr on the injectors? Maybe he didn't scale the tune properly for the larger injectors.

To say the readings in HP Tuners is false is stupid, kinda sounds like he doesn't know what he's saying.

[NJ_Phil]

Is it an earlier computer that has a max of 63.5lb/hr on the injectors? Maybe he didn't scale the tune properly for the larger injectors.

To say the readings in HP Tuners is false is stupid, kinda sounds like he doesn't know what he's saying.

It's a late model E67 and allows 127 lbs/hr.. Nothing is scaled as far as stoich and IVT.
Agree that was a stupid thing for his tuner to say but I'm puzzled how it can run at that duty cycle.

Some quick math shows 7000rpm is a revolution every 8.5 milliseconds * 2 for intake/exhaust cycle means the intake valve is opening every 17ms, yet the injector pulse width = 25+ milliseconds
I gotta be missing something



EDIT:
Just did dome quick calculations on one of my scans that showed 63% duty cycle running at 6700rpm with a pulse width of 11.3 ms.

6700 RPM = IV open rate of 18 milliseconds, so 18 ms would be 100 % duty cycle
11.3ms / 18ms = 62.7% calculated, scanner shows 63% so it's a simple calculation to get duty cycle from PW if RPM is known.

The guy had to give be the wrong tune and I need to upload the actual tune from the car. Gotta feeling something is scaled and he's really running half of 145%

[dreksnot]

Can only possibly run at 100% IDC. HPTuners spits out a calculated IDC with pulsewidth, pressure, flow, etc. parameters. As for the injectors being max'd out, they're keeping up if the actual AFR is the commanded AFR. However, it could be at 80%, 90%, 95% or 100% real IDC making that happen (but nothing over 100%). Definitely wouldn't hurt to increase injector size and fueling.

I've been a culprit of this phenomenon with 125% IDC until I corrected my VE tables. With the same conditions, I am now at 90-95% IDC on the same runs.

[crewdoguh60m]

new street test.hpl maybe his V is as jacked up as mine. you can see at one point I put mine into 141% duty hopfully someone can give us the answers I need

[GHuggins]

As long as you keep raising the MAF or VE the injector duty cycle will keep increasing... It's been my own personal experience that the LSA injectors max out around 130% - will not add fuel above that... I do not personally like to go above 90ish especially on something like ethanol because a few percent on the injectors can be a lot on the wideband... There are "off" settings designed into the calibration - that I'm trying to get added - that defines how long an injector can spray regardless... In other words it will only spray so long before taking a break for so many ms and then spraying again...

If your over or around 100% - get bigger injectors...

[ddtech]

OR, you're dropping fuel pressure.

IF you drop pressure, injs will open more to compensate.

[10_SS]

There are "off" settings designed into the calibration - that I'm trying to get added - that defines how long an injector can spray regardless... In other words it will only spray so long before taking a break for so many ms and then spraying again...

If your over or around 100% - get bigger injectors...

I've been wondering about this for awhile..seems like it would be a pretty important table to have access too. Do you know what any of the stock settings are? Just curious.

[GHuggins]

.7969ms - it's actually in one of the OS's now thanks to jslic... Still waiting to get added into the rest...