What triggers secondary injectors on 2008 (Gen 2)?



fns

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I am trying to find out exactly what triggers the ecu to send the signal to the secondary fuel injectors?
Here is what has brought me to this question. I built a Turbo hayabusa (gen 2) 5 years ago. I run the Power commander v-pti, power commander Ignition, Power commander secondary fuel module and larger injectors. The car has ran perfect for the past 5 years. The last dunes trip the car started to lien out in the upper Rpm's. I assumed a sensor went out or perhaps I lost the tune? I reloaded the tune and swapped "Ap sensor, iap sensor and cam sensor" no luck. Car has no codes it will just lien out in the hire Rpm's under a load. I took the car to my dyno tuner that did the car originally. He verified the secondary injectors where not firing. They have 12v but not getting a signal from the ecu. Called powercommander and they said they only modify the signal from the ecu. So if no signal from the ecu than their fuel module does nothing. I tried taking out the powercommander stuff and the same thing. Now I am back to thinking it is sensor or ecu....So I bought another 2008 hayabusa motorcycle to play the parts swap game. I switched the ecu and every sensor.. So I though it had to be my wiring grounding out and I re wired the computer....Still the same problem. Please any help with my question: what sensors or parameters triggers the ecu to send the signal to the secondary fuel injectors?
 

Boosted Cycle Perf

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It’s been running 5 years and now having issues?

all of the injectors get a constant 12 volt + on yellow wire with red stripe. They those are also all tied together. Make sure they have that. The negative trigger comes directly from the ecu.

with that said there’s no specific sensor that triggers the secondaries. That’s based off the injector balance map in the ecu.

why not ditch all the power commander stuff and just do all the tuning through the ecu?
 

fns

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All 8 injectors have the 12v on the yellow wire. I pulled the Power commander stuff off and the ecu does not sending the ground signal for the 4 secondary injectors. Pin 61,62,63,64... ?? Something is telling the ecu not to send the signal. ??Safe mode of some kind??
 

fns

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Ok. The factory injector balance table Is pretty weird. But likely just free reving the engine isn’t enough load to get to the areas where the secondaries come on.
I agree it is weird....I am hoping to find out what the factory parameters are exactly. If it is rpm based, pressure based, do they have to be in gear, does it require to be above certain temp, Voltage or a combination of a few of these things. It has worked for the past 5 year than stops...Something has come loose or gone bad. And I am at my end not knowing what I should try next. Thanks
 

Boosted Cycle Perf

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1611516

This is the factory injector balance map. Secondary’s don’t start to come on at the earliest of 40% throttle, and 5600 rpm. Even then at that point they’re only doing 2% of the fueling.

That would be very hard to monitor without it running on the dyno.

I’ll tell you this. The secondary injectors are most likely running, but you’re having a different problem. Weather fuel pressure is too low, or secondaries are clogged causing your lean condition. If the ecu doesn’t see the injectors it will kick an FI light. If the secondary power commander is shot you won’t get an fi light as the ecu still senses the proper load on those drivers .

I HIGHLY suggest ditching all the power commander stuff as eventually you’ll get problems like this when the boxes go bad as they often do.
 

HayaWakened

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View attachment 1611516
This is the factory injector balance map. Secondary’s don’t start to come on at the earliest of 40% throttle, and 5600 rpm. Even then at that point they’re only doing 2% of the fueling.

That would be very hard to monitor without it running on the dyno.

I’ll tell you this. The secondary injectors are most likely running, but you’re having a different problem. Weather fuel pressure is too low, or secondaries are clogged causing your lean condition. If the ecu doesn’t see the injectors it will kick an FI light. If the secondary power commander is shot you won’t get an fi light as the ecu still senses the proper load on those drivers .

I HIGHLY suggest ditching all the power commander stuff as eventually you’ll get problems like this when the boxes go bad as they often do.
Explain for a newb what those baseline numbers are? Column: 1600 - 15200; Row: 0 to 100)
 

Boosted Cycle Perf

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Explain for a newb what those baseline numbers are? Column: 1600 - 15200; Row: 0 to 100)
This is the table that dictates when the second set of injectors turn on, and how much of the fuel they are required to handle.

So the Y axis is RPM, the X axis is throttle position. The numbers that fill the map is the percentage of the fueling being handled by the primary (lower) set of injectors. So 100% means, only the primary injectors are running. 80% means the secondaries are doing 20% of the total fueling. If you notice in the 100% throttle column, from 7200rpm on, the primaries are only handling 20% of the fueling. My assumption is switching to the secondaries that are mounted much higher in the throttle bodies allow for greater fuel atomization in the high rpm.

This injector balance map is for a turbo application. Notice that above 70% throttle and 8k rpm, it’s 50%. At this point both sets of injectors are sharing the fueling requirements equally. This is what guys are talking about when they say their injector balance is set to 50/50.
1611540


To further beat the dead horse, the first map (factory map) is the reason why guys that are trying to tune their gen 2 busas with a power commander only on E85 end up running out of injector. Because at no point are both injectors sharing the workload.

Also, in fns case, has a power commander, and a secondary fuel module it adds a level of tuning complexity. Basically you’re tuning each row of injectors separately to try and overcome the ecus command to move fueling from one set to the other, while also trying to match the fueling the engine needs at any given rpm, and boost level. Because of all that, it’s extremely hard to get the most efficiency out of the fuel system. For example, on a boosted gen 2, stock injectors can support 350whp max. But when tuning around the curve of the stock ecu mapping, you’re likely only to get a little over 300hp using a pc, and secondary controller.
 

Boosted Cycle Perf

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I agree it is weird....I am hoping to find out what the factory parameters are exactly. If it is rpm based, pressure based, do they have to be in gear, does it require to be above certain temp, Voltage or a combination of a few of these things. It has worked for the past 5 year than stops...Something has come loose or gone bad. And I am at my end not knowing what I should try next. Thanks
Where are you located? I have a car dyno and have done many sand rails, trex’s, and mini cars with Busa engines.
 

fns

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Thank you for taking the time to help. I am located in Phoenix Arizona. I own a small motorcycle dealership called "Dwn N Out" (Just got google 360 photos done).. So I would not say I am an expert but I do have some experience around motorcycle's. This is one reason this is pissing me off that I can not figure it out. I did take the car to the my friends dyno. (Xact dyno) He also verified the ecu was not sending a signal to the secondary injectors....I did find someone that claimed he had the same issue and it was his crank sensor out of range? When I get a chance later tonight I will check that.
 

fns

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Update...I checked my 5v reference pin 11 and found it has a short to ground. Now looking for what sensor or wire that is causing that.
 

moondo

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great support and knowledge base, boosted Cycle.

With all the big injectors being offered , its interesting to point out the massive HP potential or the stock setup, which also has beautiul atomization compared to others with lesser hole count or pintles,No? I went back to stock and ECU editor, but still working that transition zone admittedly

you are in houston , right?

-moondo
 


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