why am I seeing 90% inj duty with 2 pumps?
05-15-07, 02:59 PM
#1
why am I seeing 90% inj duty with 2 pumps?
Just thought I would ask here before I started checking everything. I am running a rx7.com pump and a walbro intake. this weekend at 1.44bar (21psi) I saw 91% inj duty cycle. With those numbers it looks like I am running on only one pump. I guess I will start with the walbro pump. I had bad thought when i bought it!! Oh running 1000 prim and 1600 2nds.
05-15-07, 06:08 PM
#6
Hey, where did my $$$ go?
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How did you run the fuel lines? Could there be anywhere in the lines that is restricting the fuel? Was the walbro new or used? could there be a install issue?
05-15-07, 06:55 PM
#7
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its probably beause your ecu is telling your injectors to run that high of a duty cycle. if your pig rich at that level you could lean it out, or if your lean then you need bigger injetors.
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05-15-07, 07:18 PM
#8
For now I have the walbro (new unit) running through stock hard lines to primary rail. rx7.com pump running with -6 to secondary rail. Both tie in to each side of the aeromotive reg. then return with stock return line. I am going to change this around either way as I want a bigger return and another -6 feed. I also am going to go with another rx7.com pump in place of the walbro.
I am going to start with the pump (walbro) as last time on the dyno I was hitting 89% duty at 21-22psi with same 1000/ 1680's. I was thinking it was the way Brian had the PFC set up. Were the injectors settings are we changed them from 100% to 65%. I was thinking this was allowing only 65% of my injector to be used? But I think that is wrong?
A/R's were high 10's low 11's.
I am going to start with the pump (walbro) as last time on the dyno I was hitting 89% duty at 21-22psi with same 1000/ 1680's. I was thinking it was the way Brian had the PFC set up. Were the injectors settings are we changed them from 100% to 65%. I was thinking this was allowing only 65% of my injector to be used? But I think that is wrong?
A/R's were high 10's low 11's.
05-16-07, 03:59 PM
#9
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Your problem lies in your pump set up. At 21 psi you are maxing the flow of one pump. The walbro is rated to supply flow for up to 4 liters. you are set up for about 5.3 liters. there is why you have a hight duty cycle.
I did run some tests with data logs on my dual walbro. with two gss341s at 15 psi and same injectors as you, my duty was 54 %. disabling one pump for the same 15 psi, my duty cycle shot up to 86%. so no wonder at psi you are seeing 90%.
I will try to look up for an article i saved a while ago which compares the bnr,stock, walbro and another pump. it is very comprehensive.
your pump setup is as weak as your strongest link. for those injectors, you require a good feed, IE two -6an lines, and a must is two pumps. I am positive, that the demand on the pump is too high.
also, what power are you supplying the walbro? if you are using the OEM voltage shredder, then you are burning the pump out. the walbro is setup for a constant 13.7 volt, that is directly from the alternator. the stock wiring from the ecu/ relay/ voltage switch is not sufficient to run the walbro. this will also increase you duty sky high!
I will try to find that article asap
Best,
George
I did run some tests with data logs on my dual walbro. with two gss341s at 15 psi and same injectors as you, my duty was 54 %. disabling one pump for the same 15 psi, my duty cycle shot up to 86%. so no wonder at psi you are seeing 90%.
I will try to look up for an article i saved a while ago which compares the bnr,stock, walbro and another pump. it is very comprehensive.
your pump setup is as weak as your strongest link. for those injectors, you require a good feed, IE two -6an lines, and a must is two pumps. I am positive, that the demand on the pump is too high.
also, what power are you supplying the walbro? if you are using the OEM voltage shredder, then you are burning the pump out. the walbro is setup for a constant 13.7 volt, that is directly from the alternator. the stock wiring from the ecu/ relay/ voltage switch is not sufficient to run the walbro. this will also increase you duty sky high!
I will try to find that article asap
Best,
George
05-16-07, 04:49 PM
#10
No, 21-22psi was the amount of boost I was at when I hit 91% duty cycle.
I have an upgraded relay and wire feed (I think 10 guage). I direct wire the relay from battery. using the stock relay to turn on the upgraded relay. I really think its going to be a walbro pump issue as I had reached the same duty cycle when I was running on the one pump before.
I have an upgraded relay and wire feed (I think 10 guage). I direct wire the relay from battery. using the stock relay to turn on the upgraded relay. I really think its going to be a walbro pump issue as I had reached the same duty cycle when I was running on the one pump before.
05-16-07, 10:49 PM
#14
[QUOTE=classicauto;6947733]Are the pumps staged? NO,
Or do they run all the time? Yes
What kind of power are you running and can you verify when its on the dyno that pressure is in fact rising in relation to boost? (1:1)
No, I can not say that forsure. Power, meaning voltage?
How old is your fuel filter(s)? Stock one 3-4 years old with 3-4k miles and the other (inline with -6 an) is new.
Thanks to everyone that has given me some ideas. I am going to do some test'sthis weekend.
Or do they run all the time? Yes
What kind of power are you running and can you verify when its on the dyno that pressure is in fact rising in relation to boost? (1:1)
No, I can not say that forsure. Power, meaning voltage?
How old is your fuel filter(s)? Stock one 3-4 years old with 3-4k miles and the other (inline with -6 an) is new.
Thanks to everyone that has given me some ideas. I am going to do some test'sthis weekend.
05-16-07, 10:57 PM
#16
The duty cycle is calculated by your ecu and it doesn't care about your fuel pressure or your fuel pump, at least on my haltech it's that way.
Duty cycle = time injectors are opened/time of one engine cycle
You can have a duty cycle of 90% at fuel pressure of 20psi or 38psi. However you will have more fuel at 38psi.
Maybe I'm wrong but I don't see how the ecu gets the fuel pressure. On my haltech it doesn't.
Duty cycle = time injectors are opened/time of one engine cycle
You can have a duty cycle of 90% at fuel pressure of 20psi or 38psi. However you will have more fuel at 38psi.
Maybe I'm wrong but I don't see how the ecu gets the fuel pressure. On my haltech it doesn't.
05-17-07, 07:01 AM
#17
Racing Rotary Since 1983
iTrader: (6)
i am really scratching my head on this thread. either you are looking in the wrong direction or i am going to learn something.... (which hopefully happens every day.)
you are running a GT42? BDC streetport w 1000/1600 injectors. at 21 psi w that setup you should be running close to 90% duty. i run two TO4s that deliver the same amount of air and before i started adding methanol i was routinely at 90% duty.
the question is are you o k w your AFR at that point?
if you run 2 fuel pumps and one malfunctions the duty cycle will not change unless you have autotune.
as FD3S posts, the duty cycle is actually a specific number of milliseconds that the injector is directed to open at a certain point (RPM & Load) on the fuel map by the ECU. the ECU can not automatically change this number. (again unless it has autotune which most do not).
you are running a first class engine (BDC) and a monster turbo and it appears you are way under instrumented. are you running a Power FC?
i suggest you need to log fuel pressure and afrs at a minimum and egts as a further help. none of this is complicated or expensive compared to a blown motor.
if you instrument you don't have to be a genius and you don't have to be lucky.
good luck,
howard coleman
you are running a GT42? BDC streetport w 1000/1600 injectors. at 21 psi w that setup you should be running close to 90% duty. i run two TO4s that deliver the same amount of air and before i started adding methanol i was routinely at 90% duty.
the question is are you o k w your AFR at that point?
if you run 2 fuel pumps and one malfunctions the duty cycle will not change unless you have autotune.
as FD3S posts, the duty cycle is actually a specific number of milliseconds that the injector is directed to open at a certain point (RPM & Load) on the fuel map by the ECU. the ECU can not automatically change this number. (again unless it has autotune which most do not).
you are running a first class engine (BDC) and a monster turbo and it appears you are way under instrumented. are you running a Power FC?
i suggest you need to log fuel pressure and afrs at a minimum and egts as a further help. none of this is complicated or expensive compared to a blown motor.
if you instrument you don't have to be a genius and you don't have to be lucky.
good luck,
howard coleman
05-17-07, 07:19 AM
#18
Banned. I got OWNED!!!
great advice from howard.
My car has its own bare essentials that are analysable any time any place with no other bits required
I have EGT, fuel pressure, exhaust back pressure, turbine back pressure, Blitz Bosch LSU 02 set up and can do 10 minutes of logging on Blitz SBC - I color ! no lap tops needed and no more guessing wondering what just happened anytime i drive the car.
Cant recommend this strongly enough, it is cheap protection for your investment at the end of the day.
I have all of the above in real time display right infront of me, especialy AFR, EGT, fuel pressure and knock of PFC hand set, I can react to any bad situation as it happens which is another topic but still very important.
My car has its own bare essentials that are analysable any time any place with no other bits required
I have EGT, fuel pressure, exhaust back pressure, turbine back pressure, Blitz Bosch LSU 02 set up and can do 10 minutes of logging on Blitz SBC - I color ! no lap tops needed and no more guessing wondering what just happened anytime i drive the car.
Cant recommend this strongly enough, it is cheap protection for your investment at the end of the day.
I have all of the above in real time display right infront of me, especialy AFR, EGT, fuel pressure and knock of PFC hand set, I can react to any bad situation as it happens which is another topic but still very important.
05-17-07, 09:33 AM
#19
i am really scratching my head on this thread. either you are looking in the wrong direction or i am going to learn something.... (which hopefully happens every day.)
you are running a GT42? BDC streetport w 1000/1600 injectors. at 21 psi w that setup you should be running close to 90% duty. i run two TO4s that deliver the same amount of air and before i started adding methanol i was routinely at 90% duty.
the question is are you o k w your AFR at that point?
if you run 2 fuel pumps and one malfunctions the duty cycle will not change unless you have autotune.
as FD3S posts, the duty cycle is actually a specific number of milliseconds that the injector is directed to open at a certain point (RPM & Load) on the fuel map by the ECU. the ECU can not automatically change this number. (again unless it has autotune which most do not).
you are running a first class engine (BDC) and a monster turbo and it appears you are way under instrumented. are you running a Power FC?
i suggest you need to log fuel pressure and afrs at a minimum and egts as a further help. none of this is complicated or expensive compared to a blown motor.
if you instrument you don't have to be a genius and you don't have to be lucky.
good luck,
howard coleman
you are running a GT42? BDC streetport w 1000/1600 injectors. at 21 psi w that setup you should be running close to 90% duty. i run two TO4s that deliver the same amount of air and before i started adding methanol i was routinely at 90% duty.
the question is are you o k w your AFR at that point?
if you run 2 fuel pumps and one malfunctions the duty cycle will not change unless you have autotune.
as FD3S posts, the duty cycle is actually a specific number of milliseconds that the injector is directed to open at a certain point (RPM & Load) on the fuel map by the ECU. the ECU can not automatically change this number. (again unless it has autotune which most do not).
you are running a first class engine (BDC) and a monster turbo and it appears you are way under instrumented. are you running a Power FC?
i suggest you need to log fuel pressure and afrs at a minimum and egts as a further help. none of this is complicated or expensive compared to a blown motor.
if you instrument you don't have to be a genius and you don't have to be lucky.
good luck,
howard coleman
Howard, I do not think I will be teaching YOU anything on rotary's here. You seem to take the cake on that one! I am the one that has a ton to learn!
Yes, I am running a PFC, LC-1 wideband. No fuel pressure guage inside just under hood. I will add one inside as suggested. How can I log fuel pressure?
Maybe these 1000cc's were miss shiped and are 850's as BDC suggested? I am ok so far with a/r's seeing low 11's at 21psi and 6800rpm. Brian (BDC) is coming in a few weeks to do some tuning on it and I just wanted to make sure everything was correct and ready. So does the pump's, lines effect duty cycle or not? I understand what duty cycle is. So if one was not getting enough pressure wouldnt he increase duty cycle to correct this if lean (to a point)? Then pump's and pressure would play a part of duty cycle. If running large injectors (I consider my set large) then the duty cycle would be less as long as pressure was good. Correct? Sorry so entry level! Just making sure I a on the right page. Thanks to all! Mike
05-17-07, 10:49 AM
#20
Howard, I do not think I will be teaching YOU anything on rotary's here. You seem to take the cake on that one! I am the one that has a ton to learn!
Yes, I am running a PFC, LC-1 wideband. No fuel pressure guage inside just under hood. I will add one inside as suggested. How can I log fuel pressure?
Maybe these 1000cc's were miss shiped and are 850's as BDC suggested? I am ok so far with a/r's seeing low 11's at 21psi and 6800rpm. Brian (BDC) is coming in a few weeks to do some tuning on it and I just wanted to make sure everything was correct and ready. So does the pump's, lines effect duty cycle or not? I understand what duty cycle is. So if one was not getting enough pressure wouldnt he increase duty cycle to correct this if lean (to a point)? Then pump's and pressure would play a part of duty cycle. If running large injectors (I consider my set large) then the duty cycle would be less as long as pressure was good. Correct? Sorry so entry level! Just making sure I a on the right page. Thanks to all! Mike
Yes, I am running a PFC, LC-1 wideband. No fuel pressure guage inside just under hood. I will add one inside as suggested. How can I log fuel pressure?
Maybe these 1000cc's were miss shiped and are 850's as BDC suggested? I am ok so far with a/r's seeing low 11's at 21psi and 6800rpm. Brian (BDC) is coming in a few weeks to do some tuning on it and I just wanted to make sure everything was correct and ready. So does the pump's, lines effect duty cycle or not? I understand what duty cycle is. So if one was not getting enough pressure wouldnt he increase duty cycle to correct this if lean (to a point)? Then pump's and pressure would play a part of duty cycle. If running large injectors (I consider my set large) then the duty cycle would be less as long as pressure was good. Correct? Sorry so entry level! Just making sure I a on the right page. Thanks to all! Mike
The duty cycle is affected by many things, as mentioned the % is simply a relation between engine cycle and how long the injector is open. At 100% they are open all the time (ie. locked and bad for the injectors)
Fuel pressure plays a role because at a 50psi a 1000cc injector will inject MORE gas at 50% duty then a 1000cc injector at 30 psi with 50% duty since the fuel will spray more intensely.
Fuel flow (ie. old filter/small lines/blocked flow) will play a role similar to pressure.
I'm curious how much power you're making at 21psi with that setup...........probably over/around 500whp? To me, there's something missing in that setup. On meth sprayed S5 13BT blocks, I've seen near 500 wheel out of 720's and 1680's with IDC's hovering in the mid/high 80's at peak power. I didn't hear it mentioned that you're spraying meth, but perhaps at that power level your engine is needing to be drown in fuel to bring the AFR's and EGT's to an acceptable level.
If you are spraying or my guesstimates/postulations are out of whack, oops
But something's a miss here and I'm out of ideas. That should be enough fuel to run 6 street cars.....
05-17-07, 12:48 PM
#21
Its possible you have a mis-shipped set of primaries. Did they come with flow sheets and what brand of injectors are they?
The duty cycle is affected by many things, as mentioned the % is simply a relation between engine cycle and how long the injector is open. At 100% they are open all the time (ie. locked and bad for the injectors)
Fuel pressure plays a role because at a 50psi a 1000cc injector will inject MORE gas at 50% duty then a 1000cc injector at 30 psi with 50% duty since the fuel will spray more intensely.
Fuel flow (ie. old filter/small lines/blocked flow) will play a role similar to pressure.
I'm curious how much power you're making at 21psi with that setup...........probably over/around 500whp? To me, there's something missing in that setup. On meth sprayed S5 13BT blocks, I've seen near 500 wheel out of 720's and 1680's with IDC's hovering in the mid/high 80's at peak power. I didn't hear it mentioned that you're spraying meth, but perhaps at that power level your engine is needing to be drown in fuel to bring the AFR's and EGT's to an acceptable level.
If you are spraying or my guesstimates/postulations are out of whack, oops But something's a miss here and I'm out of ideas. That should be enough fuel to run 6 street cars.....
The duty cycle is affected by many things, as mentioned the % is simply a relation between engine cycle and how long the injector is open. At 100% they are open all the time (ie. locked and bad for the injectors)
Fuel pressure plays a role because at a 50psi a 1000cc injector will inject MORE gas at 50% duty then a 1000cc injector at 30 psi with 50% duty since the fuel will spray more intensely.
Fuel flow (ie. old filter/small lines/blocked flow) will play a role similar to pressure.
I'm curious how much power you're making at 21psi with that setup...........probably over/around 500whp? To me, there's something missing in that setup. On meth sprayed S5 13BT blocks, I've seen near 500 wheel out of 720's and 1680's with IDC's hovering in the mid/high 80's at peak power. I didn't hear it mentioned that you're spraying meth, but perhaps at that power level your engine is needing to be drown in fuel to bring the AFR's and EGT's to an acceptable level.
If you are spraying or my guesstimates/postulations are out of whack, oops
But something's a miss here and I'm out of ideas. That should be enough fuel to run 6 street cars.....No flow sheets. I believe they are Bosch. I bought them from JAson rx7store.net. They are the greenish color if anyone can varify. No dyno numbers yet but I do expect to break 500 but not at 21psi. This is the 4094 turbo not the standard 42r. Its a 42r in a 40r size. Uses the 42r comp wheel and 40r turbine. So I expect it to take a little more boost to see over 500. I am not using meth yet. I am looking into either water or a 50/50 mix. I have a kit just not sure its the one I want to use. I will post results from fuel system if i find anything this weekend after I work on it.
05-17-07, 01:25 PM
#22
development
more pressure = more flow thru the injectors (at a given pulse rate).
so increasing pressure will adjust A:F on your entire map.
as howard suggests a log of fuel pressure will let you know when your pump can't keep up. You should be able to log fuel pressure with a 0-5V sender thru the datalogit for the PFC.
so increasing pressure will adjust A:F on your entire map.
as howard suggests a log of fuel pressure will let you know when your pump can't keep up. You should be able to log fuel pressure with a 0-5V sender thru the datalogit for the PFC.
05-17-07, 06:50 PM
#23
How much power did you make at 21 to 22psi?
There is now way you can be maxing those injectors if power levels are the norm at that level of boost.
You need to check your fuel supply out. I have done 600 rwhp with a 750/1600cc injector combo at 100% duty cycle or around 570 to 580 rwhp at a safer duty cycle with those injectors.
It's never been a good idea to run two different pumps with different flow rates in parallel. Your fuel supply has a restriction somewhere in it.
There is now way you can be maxing those injectors if power levels are the norm at that level of boost.
You need to check your fuel supply out. I have done 600 rwhp with a 750/1600cc injector combo at 100% duty cycle or around 570 to 580 rwhp at a safer duty cycle with those injectors.
It's never been a good idea to run two different pumps with different flow rates in parallel. Your fuel supply has a restriction somewhere in it.