Injectors reachign 100% duty cycle on 10psi S14SR Blacktop - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

TTrx7Pete · 11-06-2009, 08:38 AM

Brief rundown of the car:
97 S14 with SR20DET S14 Blacktop T28 with VTC
FMIC, Walbro 255lph pump, stock injectors, full 3" exhaust, intake, PowerFC D-Jetro.

The fuel system, sans pump, is stock. I'm running 10 psi of boost and I'm constantly hitting 100% duty cycle in the upper 5.5-7k rpm range. So I don't floor it, or get into it anymore. Wondering why I am hitting 100% duty cycle as I've read on the forum over and over that 10 psi is safe boost with stock injectors.

Anything you guys think that may be set improperly? I plan on double checking the injector settings on the PFC. Anything else?

Def · 11-06-2009, 08:41 AM

Sounds about right for 370's and some bolt-ons with a GT2560R.

Some people's definition of "safe" is pretty sketchy on this forum...

s14unimog · 11-06-2009, 09:14 AM

^ I thought the S14 SR20DET had 440's? Also, can't you just say S14 SR20DET? Are there multiple models of the s14 engine?

*fliprayzin240sx* · 11-06-2009, 09:17 AM

Quote:

Originally Posted by s14unimog

^ I thought the S14 SR20DET had 440's? Also, can't you just say S14 SR20DET? Are there multiple models of the s14 engine?

Nopes...S14s got 370s just like S13s. S15s have 440s stock...

s14unimog · 11-06-2009, 09:29 AM

Good to know, thanks. So what about the whole "blacktop" S14 SR20DET?

TTrx7Pete · 11-06-2009, 10:05 AM

In any event... my question was not answered lol... I'm still wondering why I am hitting 100% duty cycle on the stock T28 Turbo.

MandTPhotography · 11-06-2009, 10:10 AM

My injectors are static at like 14lbs on a T25, 370cc's.

jspaeth · 11-06-2009, 10:30 AM

Quote:

Originally Posted by TTrx7Pete

In any event... my question was not answered lol... I'm still wondering why I am hitting 100% duty cycle on the stock T28 Turbo.

Someone already told you why. You have maxed them out. That turbo at the boost is good for probably 275 whp or so, I would guess.

And that is enough to max out those injectors at stock fuel pressure.

It's not really that mysterious to be honest.

tunersedge · 11-06-2009, 10:39 AM

Quote:

Originally Posted by TTrx7Pete

Wondering why I am hitting 100% duty cycle as I've read on the forum over and over that 10 psi is safe boost with stock injectors.

problem : you are maxing the injectors out.
solution : go bigger.

s14unimog · 11-06-2009, 01:35 PM

^that's why I thread jacked.... SO is "blacktop" necessary to be said with S14 SR20DET...?

S13 curtis · 11-06-2009, 04:33 PM

jus get a adjustable fuel pressure for now that will be a temporary fix for now.

jspaeth · 11-06-2009, 04:51 PM

Quote:

Originally Posted by S13 curtis

jus get a adjustable fuel pressure for now that will be a temporary fix for now.

Worst idea ever.

He will be running really rich everywhere else.

Fail

Def · 11-06-2009, 06:41 PM

Quote:

Originally Posted by TTrx7Pete

In any event... my question was not answered lol... I'm still wondering why I am hitting 100% duty cycle on the stock T28 Turbo.

Damn... some people are just dense.

Why don't you bump the boost up to 18 psi, it'll fix all your problems. :ghey:

TTrx7Pete · 11-06-2009, 07:55 PM

I guess I'm missing something here.... I have a stock turbo with stock injectors running only 10 psi of boost... and I'm maxxing out my injectors? I was under the impression that 10 psi of boost was the factory boost setting on the S14 SR...

So why am I having an issue at "stock" boost levels?! That is my issue.

lok · 11-07-2009, 08:21 AM

7 is stock

***S14DB*** · 11-07-2009, 08:46 AM

7 is stock wastegate. Stock EBC raises it to 10.

Check your injector settings. Do you have an wideband? know your AFR's?

10 is safe on a stock setup. You have aftermarket parts that can cause you to flow more air at the same boost. But I can only assume something is wrong with the tune and would recommend some pulls on dyno with wideband.

910noskillz · 11-07-2009, 08:51 AM

yeah, 7psi is stock.....as the reference to running 14 and the injectors being static, that is on a t25,
the t28 is a little bigger than that turbo though, and flows more air, and makes more power at lower boost levels(as opposed to a t25).....I would say that the stock injectors are good to about 250, then an upgrade would be needed.....

the point is if there maxing out, then there maxing out. theres no way around it unless you get bigger injectors....

get some bigger injectors and crank it to about 13psi, it will be worth the $350 when all is said and done....or just remove your boost controller and run stock boost

jr_ss · 11-07-2009, 11:14 AM

Hmmm, I thought that the S15 injectors were 480's? In any event, You need bigger injectors...

Cone · 11-07-2009, 11:25 AM

I know with some cars, you will hit 100 dc and it is totally fine. But to determine if there really is a problem, you need a wideband.

jr_ss · 11-08-2009, 02:32 PM

Quote:

Originally Posted by Cone

I know with some cars, you will hit 100 dc and it is totally fine. But to determine if there really is a problem, you need a wideband.

100% DC is not fine ever... Your injectors are no longer pulsing, but are staying open and pissing fuel... Bad idea

You "can" bandaid it (I use that term loosely) with a meth injection kit. This is common in the Subaru world, but I don't like the idea of relying on a small tank and pump to keep my engine from blowing up, no thank you.

johngriff · 11-08-2009, 10:04 PM

I don't like the injector duty cycle feed back on the PFC.

I have seen this too on the commander in different cars with similar setups, some will say 100% duty cycle, other will say 70%.

What is the PFC basing the duty cycle on? I know injector open times, you should probably stop around 30ms with a stock sidefeed. Maybe hook up a scope to an injector signal out on the ecu harness and log the wave at your 100% event. If you are running 26ms+ I could believe the injectors are maxed out.

s14unimog · 11-09-2009, 12:05 PM

Its surprising that there are still people on here that believe stock boost is 7psi... At any case, I would verify that the injector duty reading is correct; you're right, that shouldn't happen at stock boost levels.

TTrx7Pete · 11-09-2009, 05:43 PM

Well it starts to cut out and I'll get some knock, so I'm certain that it is maxxing out the injectors. My engine light will flash. I come from the world of rotaries, so I don't take detonation lightly. I'm just shocked that for some reason I'm hitting 100%. The car was tuned already, but I'm guess that my supporting mods might be increasing the cfm of air and I'll need an injector upgrade... I guess for now I'll just turn down the boost.

Thanks to everyone who knows what I was talking about. 10psi is the stock boost level on the SR20DET, 7 PSI is the wastegate actuator spring setting.

S13 curtis · 11-10-2009, 02:18 AM

Quote:

Originally Posted by jspaeth

Worst idea ever.

He will be running really rich everywhere else.

Fail

not really, depends on which fpr you have and if you have it tuned with the fpr.

11-06-2009, 08:38 AM	#1
TTrx7Pete Zilvia Member Join Date: Apr 2008 Location: Florida Age: 43 Posts: 179 Trader Rating: (0) Feedback Score: 0 reviews	Injectors reachign 100% duty cycle on 10psi S14SR Blacktop Brief rundown of the car: 97 S14 with SR20DET S14 Blacktop T28 with VTC FMIC, Walbro 255lph pump, stock injectors, full 3" exhaust, intake, PowerFC D-Jetro. The fuel system, sans pump, is stock. I'm running 10 psi of boost and I'm constantly hitting 100% duty cycle in the upper 5.5-7k rpm range. So I don't floor it, or get into it anymore. Wondering why I am hitting 100% duty cycle as I've read on the forum over and over that 10 psi is safe boost with stock injectors. Anything you guys think that may be set improperly? I plan on double checking the injector settings on the PFC. Anything else? __________________ 1993 AW Mazda RX-7 1997 Nissan Silvia

11-06-2009, 08:41 AM	#2
Def Post Whore! Join Date: Apr 2004 Location: Houston, TX Posts: 2,701 Trader Rating: (16) Feedback Score: 16 reviews	Sounds about right for 370's and some bolt-ons with a GT2560R. Some people's definition of "safe" is pretty sketchy on this forum... __________________ S13 Hatch - Goes around tracks quickly DEFSPORT

11-06-2009, 09:14 AM	#3
s14unimog Nissanaholic! Join Date: Dec 2003 Location: In a place, near a river, over a lake Age: 38 Posts: 2,415 Trader Rating: (22) Rides Gallery: s14unimog Feedback Score: 22 reviews	^ I thought the S14 SR20DET had 440's? Also, can't you just say S14 SR20DET? Are there multiple models of the s14 engine? __________________ Fuking ginger bread man stole my wallet... SHIFT*lock_slide to side d3m3rs0n: if i have a baby im naming it Brandons Fault Emerson

11-06-2009, 09:29 AM	#5
s14unimog Nissanaholic! Join Date: Dec 2003 Location: In a place, near a river, over a lake Age: 38 Posts: 2,415 Trader Rating: (22) Rides Gallery: s14unimog Feedback Score: 22 reviews	Good to know, thanks. So what about the whole "blacktop" S14 SR20DET? __________________ Fuking ginger bread man stole my wallet... SHIFT*lock_slide to side d3m3rs0n: if i have a baby im naming it Brandons Fault Emerson

11-06-2009, 10:05 AM	#6
TTrx7Pete Zilvia Member Join Date: Apr 2008 Location: Florida Age: 43 Posts: 179 Trader Rating: (0) Feedback Score: 0 reviews	In any event... my question was not answered lol... I'm still wondering why I am hitting 100% duty cycle on the stock T28 Turbo. __________________ 1993 AW Mazda RX-7 1997 Nissan Silvia

11-06-2009, 10:10 AM	#7
MandTPhotography Zilvia Addict Join Date: Jul 2008 Location: Wilmington, NC Posts: 801 Trader Rating: (2) Feedback Score: 2 reviews	My injectors are static at like 14lbs on a T25, 370cc's.

11-06-2009, 01:35 PM	#10
s14unimog Nissanaholic! Join Date: Dec 2003 Location: In a place, near a river, over a lake Age: 38 Posts: 2,415 Trader Rating: (22) Rides Gallery: s14unimog Feedback Score: 22 reviews	^that's why I thread jacked.... SO is "blacktop" necessary to be said with S14 SR20DET...? __________________ Fuking ginger bread man stole my wallet... SHIFT*lock_slide to side d3m3rs0n: if i have a baby im naming it Brandons Fault Emerson

11-06-2009, 04:33 PM	#11
S13 curtis Zilvia Addict Join Date: Jun 2008 Location: Orlando,FL Age: 34 Posts: 651 Trader Rating: (13) Feedback Score: 13 reviews	jus get a adjustable fuel pressure for now that will be a temporary fix for now.

11-06-2009, 07:55 PM	#14
TTrx7Pete Zilvia Member Join Date: Apr 2008 Location: Florida Age: 43 Posts: 179 Trader Rating: (0) Feedback Score: 0 reviews	I guess I'm missing something here.... I have a stock turbo with stock injectors running only 10 psi of boost... and I'm maxxing out my injectors? I was under the impression that 10 psi of boost was the factory boost setting on the S14 SR... So why am I having an issue at "stock" boost levels?! That is my issue. __________________ 1993 AW Mazda RX-7 1997 Nissan Silvia

11-07-2009, 08:21 AM	#15
lok Zilvia Addict Join Date: Jul 2003 Location: Oklahoma Posts: 816 Trader Rating: (10) Feedback Score: 10 reviews	7 is stock

11-07-2009, 08:46 AM	#16
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	7 is stock wastegate. Stock EBC raises it to 10. Check your injector settings. Do you have an wideband? know your AFR's? 10 is safe on a stock setup. You have aftermarket parts that can cause you to flow more air at the same boost. But I can only assume something is wrong with the tune and would recommend some pulls on dyno with wideband. __________________ Comments should be taken as Opinions not as Statements of Fact

11-07-2009, 08:51 AM	#17
910noskillz Join Date: Mar 2009 Location: Wilm NC Age: 35 Posts: 47 Trader Rating: (0) Feedback Score: 0 reviews	yeah, 7psi is stock.....as the reference to running 14 and the injectors being static, that is on a t25, the t28 is a little bigger than that turbo though, and flows more air, and makes more power at lower boost levels(as opposed to a t25).....I would say that the stock injectors are good to about 250, then an upgrade would be needed..... the point is if there maxing out, then there maxing out. theres no way around it unless you get bigger injectors.... get some bigger injectors and crank it to about 13psi, it will be worth the $350 when all is said and done....or just remove your boost controller and run stock boost

11-07-2009, 11:14 AM	#18
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,415 Trader Rating: (35) Feedback Score: 35 reviews	Hmmm, I thought that the S15 injectors were 480's? In any event, You need bigger injectors... __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

11-07-2009, 11:25 AM	#19
Cone Leaky Injector Join Date: Jan 2006 Location: Portland, OR Posts: 85 Trader Rating: (0) Feedback Score: 0 reviews	I know with some cars, you will hit 100 dc and it is totally fine. But to determine if there really is a problem, you need a wideband.

11-08-2009, 10:04 PM	#21
johngriff Post Whore! Join Date: Jun 2004 Location: Long Beach, CA Posts: 4,103 Trader Rating: (4) Rides Gallery: johngriff Feedback Score: 4 reviews	I don't like the injector duty cycle feed back on the PFC. I have seen this too on the commander in different cars with similar setups, some will say 100% duty cycle, other will say 70%. What is the PFC basing the duty cycle on? I know injector open times, you should probably stop around 30ms with a stock sidefeed. Maybe hook up a scope to an injector signal out on the ecu harness and log the wave at your 100% event. If you are running 26ms+ I could believe the injectors are maxed out. __________________ [email protected]

11-09-2009, 12:05 PM	#22
s14unimog Nissanaholic! Join Date: Dec 2003 Location: In a place, near a river, over a lake Age: 38 Posts: 2,415 Trader Rating: (22) Rides Gallery: s14unimog Feedback Score: 22 reviews	Its surprising that there are still people on here that believe stock boost is 7psi... At any case, I would verify that the injector duty reading is correct; you're right, that shouldn't happen at stock boost levels. __________________ Fuking ginger bread man stole my wallet... SHIFT*lock_slide to side d3m3rs0n: if i have a baby im naming it Brandons Fault Emerson

11-09-2009, 05:43 PM	#23
TTrx7Pete Zilvia Member Join Date: Apr 2008 Location: Florida Age: 43 Posts: 179 Trader Rating: (0) Feedback Score: 0 reviews	Well it starts to cut out and I'll get some knock, so I'm certain that it is maxxing out the injectors. My engine light will flash. I come from the world of rotaries, so I don't take detonation lightly. I'm just shocked that for some reason I'm hitting 100%. The car was tuned already, but I'm guess that my supporting mods might be increasing the cfm of air and I'll need an injector upgrade... I guess for now I'll just turn down the boost. Thanks to everyone who knows what I was talking about. 10psi is the stock boost level on the SR20DET, 7 PSI is the wastegate actuator spring setting. __________________ 1993 AW Mazda RX-7 1997 Nissan Silvia