Hey guys. Is there any formula for tuning duration for different size injectors.? Coming from tuning gas engines and using larger injectors you can just punch in what your injectors flow and it adjusts the injector pulse width for you. Is there such a thing for our truck? If not aren't you pretty much shooting in the dark as far as tuning pulse width and creating a really clean tune?
Injector scaling
- Thread starter V8 HUNTER
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ramthiscummins
New member
I don't think it is that easy. It would depend on how you write the tune. Some use more timing duration or pulse width to make the same horsepower. Why would you want a 300hp truck with 200% overs??
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ramthiscummins
New member
Also isn't there a minimum pulse width for injectors.
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EverydayDiesel
I drink diesel
Isnt it as easy as cutting the injector duration by 50%? (since they are 2x stock)
This should get you back close to where you were and then you can just adjust the fuel in the upper cells as needed.
This should get you back close to where you were and then you can just adjust the fuel in the upper cells as needed.
JWhite
Trained monkey
2x would be more like 100% over. Thats always a place to start, but usually only at full pressure. As pressure decreases so does the effective percentage oversize. Flow sheets are very helpful in that not all injectors are created equal.
In some cases, depending on the size / style of the nozzle it may take more pulse width in the idle areas to achieve a stock injection amount. ( Like changing from a vco to a sac nozzle)
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chris lang
New member
How does one use their flow sheet to build the fueling map?
My injectors flow 489.2 mm3 at 180 mpa and 2800 us
276.1 mm3 at 160 mpa and 1700 us
1.94 mm3 at 100 mpa and 160 us
How do I convert this into data to plug into the map?
My injectors flow 489.2 mm3 at 180 mpa and 2800 us
276.1 mm3 at 160 mpa and 1700 us
1.94 mm3 at 100 mpa and 160 us
How do I convert this into data to plug into the map?
paulb
New member
Trying to do a stock hp tune with 200% overs would be very difficult, and I'm not sure why you would want to do that. If all you are wanting to do is limit max hp, then there are easier ways to do it then adjusting the duration table.
A couple of comments... Injector flow is not linear to injector duration. If you look at an injector flow sheet (especially easy to see if the flow sheet includes a graph), you will see that the amount of flow delivered changes dramatically with duration. If body mods have been done to the injector, then in most cases low duration fueling will also increase.
Depending on the year most ecm calibrations will cut any injection event that is less then 160us. So at an idle if you cut the duration to much, then the ecm may switch back and forth between a single event cycle and a multi event cycle. This will cause at the very least a rough idle, if not a "lope".
If you truly wanted to use the duration map, to remap the injector output to match a stock injector delivery, you would need to determine what the injector flow is at every point in the map. In other words for that particular injector how much flow is happening at the intersection of each x and y axis. I have never seen a flow sheet that gives you that much information, so you would end up having to plot the know points, and extrapolate from there.
Hope this helps...
Paul
A couple of comments... Injector flow is not linear to injector duration. If you look at an injector flow sheet (especially easy to see if the flow sheet includes a graph), you will see that the amount of flow delivered changes dramatically with duration. If body mods have been done to the injector, then in most cases low duration fueling will also increase.
Depending on the year most ecm calibrations will cut any injection event that is less then 160us. So at an idle if you cut the duration to much, then the ecm may switch back and forth between a single event cycle and a multi event cycle. This will cause at the very least a rough idle, if not a "lope".
If you truly wanted to use the duration map, to remap the injector output to match a stock injector delivery, you would need to determine what the injector flow is at every point in the map. In other words for that particular injector how much flow is happening at the intersection of each x and y axis. I have never seen a flow sheet that gives you that much information, so you would end up having to plot the know points, and extrapolate from there.
Hope this helps...
Paul