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I supported Toymods
Location:
Sydney
Registered:
May 2002
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Injector Duty Cycles
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Wed, 06 July 2005 10:44
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I've been reading around trying to find some info about this.
On my AVC-R unit I have hooked up the injector singal. To which it displays about 70% at idle and somewhat 81-84.5% at throttle. Where should this be sitting at? My AFR runs as rich as 10.5 from 5,000RPM to redline.
What is the nominal duty rate they should be?
84-5% seems high on 440CC injectors. This figure comes on with about 40% throttle applied. Should I be concerned about this? Like is it maxing out the injectors or something could be wrong with them?
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Location:
brisbane
Registered:
December 2004
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Location:
sunny coast, qld
Registered:
October 2002
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Re: Injector Duty Cycles
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Wed, 06 July 2005 22:54
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I agree. my 550's on a 6 cyl are at 2% at idle.
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Location:
sydney
Registered:
March 2003
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Re: Injector Duty Cycles
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Wed, 06 July 2005 22:58
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u cannot go buy duty cycle to test yr mixtures
plus if u have a cheap air fuel ratio meter from a car parts shop then they suck big time
they are the most inaccurate worthless gauges u can buy for reading mixtures
the cost of an engine is way too expensive to use one of those for reading mixtures
they will always read rich when full throttle
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Location:
Sydney
Registered:
April 2004
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Re: Injector Duty Cycles
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Thu, 07 July 2005 05:18
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I have a friend with a 92 red top sr20 with injectors from an aus s15 and he hits 100% duty cycle(reading from PowerFC Commander) all the damn time, only pushing out 180rwkw on stock turbo.
At idle and normal driving its fine but when you get on it you get 100% all the time.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: Injector Duty Cycles
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Thu, 07 July 2005 05:24
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only 180rwkw? They only make 150kw at the fly stock so that is pushing the limits of the injectors. Time for some bigger ones.
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Location:
brisbane
Registered:
December 2004
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Re: Injector Duty Cycles
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Thu, 07 July 2005 06:23
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wat size injectors does the sr20 have though
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Location:
Melbourne
Registered:
January 2003
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Re: Injector Duty Cycles
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Thu, 07 July 2005 06:55
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I second want Sideshow said , you cannot go of any of the reading you are getting from a cheap air fuel ratio , or any readings that you are getting from a voltage from the cars oxygen sensor like all that Apexi gear . They all read 10+ ratio as soon as the engine is underload . Also placement of the sensor plays into this alot .Most good dyno tuners have Motec ,Autronic sensor and use them externally in the exhaust unless you have added another port for tuning .
As for the sr being at 100% duty , i was at 83% at 180rwkw . He must be running a t25g at 1.2 bar to get there if the turbo is still stock , that might have something to do with the fuel mixture due to the inefficiencies of the stock turbo at that level . Also the fuel pressure rate rise of the stock regulator will never keep up , next the stock mapping will run at about 10.0 above 4000rpm to protect the engine from detonation . Funny that with a more efficient turbo on the stock ecu the ratio is way leaner throughout the rev range , and the fuel pressure didn't need to be run at such great pressure as before so the injectors where for sure not operating at the same rate as well as more power at 0.8bar . From memory the stock redtop units are only 380 units ? s15 are 440cc ?
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Location:
Wollongong
Registered:
November 2004
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Re: Injector Duty Cycles
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Thu, 07 July 2005 07:28
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| Chris Davey wrote on Thu, 07 July 2005 15:24 |
only 180rwkw? They only make 150kw at the fly stock so that is pushing the limits of the injectors. Time for some bigger ones.
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Agreed...
180RWKW is about the top of the injectors DC on an SR20DET in the Silvias etc...
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Location:
Sydney
Registered:
April 2004
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Re: Injector Duty Cycles
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Fri, 08 July 2005 02:59
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| improvedae86 wrote on Thu, 07 July 2005 16:55 |
As for the sr being at 100% duty , i was at 83% at 180rwkw . He must be running a t25g at 1.2 bar to get there if the turbo is still stock , that might have something to do with the fuel mixture due to the inefficiencies of the stock turbo at that level . Also the fuel pressure rate rise of the stock regulator will never keep up , next the stock mapping will run at about 10.0 above 4000rpm to protect the engine from detonation . Funny that with a more efficient turbo on the stock ecu the ratio is way leaner throughout the rev range , and the fuel pressure didn't need to be run at such great pressure as before so the injectors where for sure not operating at the same rate as well as more power at 0.8bar . From memory the stock redtop units are only 380 units ? s15 are 440cc ?
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Sounds about right. I remember Colin at ricol saying the duty will be a bit higher as its runnin rich as the turbo is at its limit. Its runnin the t25g, well was, kinda shat itself, nice metal grinding soundw come from it now at idle, putting in a new t28 bb in this weekend, should be fun.
I am pretty sure the S15 ones were 440cc
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Toymods member
I supported Toymods
Location:
Rydalmere, NSW
Registered:
May 2002
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Re: Injector Duty Cycles
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Fri, 08 July 2005 03:19
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| Chris Davey wrote on Thu, 07 July 2005 08:54 |
I agree. my 550's on a 6 cyl are at 2% at idle.
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Yep. My stock 3S-GTE 540cc injectors are going on 1.3 - 1.5% at warm idle, and the peak injector duty of mine has never gotten above 80%, even last weekend on the dyno. Got an external Sard fuel reg set at ~40Psi as well as the stock GT-Four fuel pump and an external 500hp Bosch pump.  I find it's a very decent setup and stable too.
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