Fuel Pressure at Idle 750cc injectors?

pokeyl · 05-16-2015, 12:20 PM

Anyone running 700 or 750cc injectors with a non bypass (stock with a larger pump) system and know there fuel pressure. I just added a port and if the electronic sensor and the rest of the electronics are correctit is over 50 PSI at idle. I falls to 37.5 at any throttle setting above idle. I think the short cycle time of the 750cc injectors with the higher pump volume is more that the factory in tank regulator can bypass.

KratikosG37 · 05-16-2015, 05:56 PM

Take it your under boost? Be better if you listed your mods in the thread.

pokeyl · 05-16-2015, 06:18 PM

GTM 1.5 SC, 750cc injectors, 255LPM pump. Custom tune from Bear383's file custom 82mm pulley (13 PSI)

Items in work - stealth nitrous with remote opener.

When I add the extra fuel with the 750cc injectors I need to make sure the fuel pressure holds. A 50 shot ramped in as a function of RPM (gears 3-6) should produce 650 RWHP and 500-ish torque smooth enough to make the stock internals last.

pokeyl · 05-18-2015, 06:57 PM

I took some more readings 63.75 at idle. 56.25 off idle. any toughs? before start 48.75

phunk · 05-18-2015, 07:29 PM

Your injectors have nothing to do with your fuel pressure.

Most likely, you upgraded your fuel pump, and did not modify your pump module to support the fuel pump.

CJM: Ultimate 370z Fuel Pump Thread

pokeyl · 05-18-2015, 08:23 PM

Quote:

Originally Posted by phunk

Your injectors have nothing to do with your fuel pressure.

Most likely, you upgraded your fuel pump, and did not modify your pump module to support the fuel pump.

CJM: Ultimate 370z Fuel Pump Thread

CORRECT I did not, but I will. Thanks

ANMVQ · 05-19-2015, 02:53 PM

1.5 SC and NOS this is going to end well :/. Why people why

Jordo! · 05-19-2015, 03:23 PM

They may have a different latency setting too -- are you sure you have all the correct spec data inputted into the fuel injector tables?

Examples of what I'm talking about:

Theory: An Injector Model « Moates Support

https://github.com/javiermuniz/tunin...jector-Scaling

I think on uprev you can adjust this -- possibly by way of the k multiplier?

phunk · 05-19-2015, 04:04 PM

Injector latency settings will not have any side effects on fuel pressure. I have never seen a latency table in the UpRev before, but it all gets tuned around anyway.

pokeyl · 06-02-2015, 08:48 PM

2 weeks on the road, back now. After some math, I have a 11.5 PSI drop in fuel pressure from idle to WOT. Cruse is almost the same as Idle, only a 2.5-3.2 PSI drop. I can't be sure if of the starting pressure. I do have gauge that reads in .25 lbs but it needs calibrated. I hope to see the Idle pressure come down with the next fuel system mod. I have a spare stock pump assy and will be installing a 340 LPH in it with HD wiring and DPST high amp relay.

05-16-2015, 12:20 PM	#1 (permalink)
pokeyl Track Member Join Date: Nov 2010 Location: DFS Posts: 891 Drives: ??? Rep Power: 54	Fuel Pressure at Idle 750cc injectors? Anyone running 700 or 750cc injectors with a non bypass (stock with a larger pump) system and know there fuel pressure. I just added a port and if the electronic sensor and the rest of the electronics are correctit is over 50 PSI at idle. I falls to 37.5 at any throttle setting above idle. I think the short cycle time of the 750cc injectors with the higher pump volume is more that the factory in tank regulator can bypass. __________________ It's not my fault I'm old, I was born a very long time ago!

05-16-2015, 05:56 PM	#2 (permalink)
KratikosG37 Enthusiast Member Join Date: Jun 2014 Location: New Orleans, LA Posts: 273 Drives: 09 TT Wrapped G37 Rep Power: 10	Take it your under boost? Be better if you listed your mods in the thread. __________________ KratikosG37 Build Log http://www.myg37.com/forums/build-th...ml#post3888739

05-16-2015, 06:18 PM	#3 (permalink)
pokeyl Track Member Join Date: Nov 2010 Location: DFS Posts: 891 Drives: ??? Rep Power: 54	GTM 1.5 SC, 750cc injectors, 255LPM pump. Custom tune from Bear383's file custom 82mm pulley (13 PSI) Items in work - stealth nitrous with remote opener. When I add the extra fuel with the 750cc injectors I need to make sure the fuel pressure holds. A 50 shot ramped in as a function of RPM (gears 3-6) should produce 650 RWHP and 500-ish torque smooth enough to make the stock internals last. __________________ It's not my fault I'm old, I was born a very long time ago!

05-18-2015, 06:57 PM	#4 (permalink)
pokeyl Track Member Join Date: Nov 2010 Location: DFS Posts: 891 Drives: ??? Rep Power: 54	I took some more readings 63.75 at idle. 56.25 off idle. any toughs? before start 48.75 __________________ It's not my fault I'm old, I was born a very long time ago!

05-18-2015, 07:29 PM	#5 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,654 Drives: 370 Rep Power: 944523	Your injectors have nothing to do with your fuel pressure. Most likely, you upgraded your fuel pump, and did not modify your pump module to support the fuel pump. CJM: Ultimate 370z Fuel Pump Thread bullitt5897, Jordo! and KratikosG37 like this. __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph

05-19-2015, 02:53 PM	#7 (permalink)
ANMVQ A True Z Fanatic Join Date: Mar 2011 Location: Framingham MA Posts: 2,732 Drives: 2014 Q50 AWD Rep Power: 19	1.5 SC and NOS this is going to end well :/. Why people why __________________ 14 Q50 AWD, ARK, ECUTEK (SEB), Takda,

05-19-2015, 03:23 PM	#8 (permalink)
Jordo! A True Z Fanatic Join Date: May 2010 Location: nirvana Posts: 6,394 Drives: 2023 NATM Rep Power: 417	They may have a different latency setting too -- are you sure you have all the correct spec data inputted into the fuel injector tables? Examples of what I'm talking about: Theory: An Injector Model « Moates Support https://github.com/javiermuniz/tunin...jector-Scaling I think on uprev you can adjust this -- possibly by way of the k multiplier? __________________ Enjoy it. Destroy it. Last edited by Jordo!; 05-19-2015 at 03:25 PM.

05-19-2015, 04:04 PM	#9 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,654 Drives: 370 Rep Power: 944523	Injector latency settings will not have any side effects on fuel pressure. I have never seen a latency table in the UpRev before, but it all gets tuned around anyway. __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph

06-02-2015, 08:48 PM	#10 (permalink)
pokeyl Track Member Join Date: Nov 2010 Location: DFS Posts: 891 Drives: ??? Rep Power: 54	2 weeks on the road, back now. After some math, I have a 11.5 PSI drop in fuel pressure from idle to WOT. Cruse is almost the same as Idle, only a 2.5-3.2 PSI drop. I can't be sure if of the starting pressure. I do have gauge that reads in .25 lbs but it needs calibrated. I hope to see the Idle pressure come down with the next fuel system mod. I have a spare stock pump assy and will be installing a 340 LPH in it with HD wiring and DPST high amp relay. __________________ It's not my fault I'm old, I was born a very long time ago!

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