Yeah not surprised at seeing 85% or more duty with a bunch of bolt-ons and stock injectors running approximately 21psi..

 

I was surprised to see how high mine was. I saw as high as 115% at 7500 RPM with 20.5 psi and 11:1 AFR. The White Rabbit must be flowing a bit more air than the stock turbo. I just ordered some 780cc injectors from Buschur and will be throwing them in this weekend. It has typically been accepted on the forums that bigger injectors are not needed until after upgrading beyond a stock based turbo, but a lot of people may begin finding their duty cycles outside of their comfort zone now that it is fairly easy to log.

-Paul

 

Duty cycles are calculated by IPW, so its not surprising to see over 100%

AFR, Fuel pressure, Boost level, all make a huge difference.. I saw high duty cycles on mine with the stock turbo too, but my airflow levels were higher than average and so was the load, but AFR's were typically richer..

I just touch 60% now on the 1000cc injectors, the car is running slightly leaner than I would want, I'm trying to match up the ECU maps to the cars actual AFR as closely as possible, then I'll tune the car fully.. Whats interesting is I had experimented with different scaling and latency values, and my duty cycle was higher, while the IPW was lower in other situations, but I found ways of getting injectors as large as 1600cc to work with the stock ECU.

 

at 20.5psi the white rabbit doesnt flow much more air than stock.. If you have really high duty cycles, then your fuel pump may not be providing enough pressure so the tuning would compensate by increasing the duty cycles.. The only time I saw high duty cycles with that combo was with a stock pump, or a walbro with low output volume. Don't get me wrong, the stock injectors are a bit small for that combo, but I would double check the fuel pressure.

 

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Oh and I wanted to add, there are a few new settings that were recently found specific to injector scaling that may affect how we scale injectors, so far we have the tools to do a good job, but after I figure out what affect some of these settings have, and what they mean, I'll post more about it..

 

I thought ipw and duty cycle were reletivly unrelated in that pulse width is a measure of how long the injector is held open in relation to time for eg... 100% pulse width is injector open all the time and 0% is closed all the time. duty cycle is frequency that a predetermined duration pulse is sent to the injector making duty cycle a hz reading.
Is the duty cycle pecentage a percentage of the max rateing for the injector?
or am I just wrong altogether

 

never mind I was wrong


duty cycle
- Duty cycle is the proportion of time during which a component, device, or system is operated. The duty cycle can be expressed as a ratio or as a percentage. Suppose a disk drive operates for 1 second, then is shut off for 99 seconds, then is run for 1 second again, and so on. The drive runs for one out of 100 seconds, or 1/100 of the time, and its duty cycle is therefore 1/100, or 1 percent.

 

No andenbre, I'm not sure how you were wrong. I was with your definition completely. 100% duty ratio is an injector always on. 0% is always off.

Duty ratio is the percentage of time on vs. time off. How do we get above 100%? I mean, I understand it's a calculated value, but does that mean that when it exceeds 100% it just holds the injector open (so nothing extra happens)? Or is this some intermediate variable than then gets corrected to 0-100% scale for the actual injector control?

Or are you defining "duty cycle" differently than the common term "duty ratio"?

 

Also, has anyone confirmed the accuracy of IPW in EVOScan? I mean, has anyone compared it to an OBD2 datalogger to see if it matches?

I'm surprised we're three revs into this software and still unsure about some of the values' accuracy (coolant temp and intake air temp come to mind). I wish I had a different logger to verify.

 

This question could be related to my following question.

Is the IPW logged with EvoScan the ammount of time that the injector is receiving the signal or the time that the ECU thinks that it's open? Latency is the amount of time that it take the injector to go from fully closed to fully open, is that correct? So...

IPW in EvoScan = time that ECU is sending the open signal

OR

IPW in EvoScan = time that ECU is sending the open signal - injector latency

Does any of that make any sense.

 

The IPW logged is the amount of time the open signal is sent to the injector.

The ECU adds any injector latencies to the pulsewidth.


Eric

 

IDC is calculated from the pulse width, latency, ,rpm, etc.. There appears to be several parameters in the ECU for max pulse width and a few other relevent values. I'm still trying to figure out how each affects the settings, but there also appears to be an additional latency value independent of voltage which is probably the dead time value.

I have had quite a bit of trouble getting the injectors to "work perfectly" which led me to start searching for additional parameters.

It turns out that the parameters for specific functions seem to be grouped together, the MAF configuration, injector settings, etc, all look to be grouped together, so finding additional parameters is sometimes as easy as looking in the rom in those areas.

 

I would be interested in what you found.

DSMLink used a deadtime value and injector scaling (global fuel) to tune the injectors. I made a post about the method for tuning injectors somewhere around here with my DSMLink method in mind.

DSMLink just used one deadtime value, it wasn't based off of voltage like the latency maps that we see in ECUFlash.

I'm curious if there is a deadtime value along with latency values for fine tuning based on battery voltage. If so, tuning injectors would be much easier, since the deadtime is really the important factor per injector brand/size. I think the latency tables, as mentioned, is for fine tweaking for voltages, etc.


Eric

 

yeah I was kinda curious how we got over 100% unless that was the value the ecu determined it needed to hit target fuel ratios regardless of what is possible.