Hks2835 Tune

[GTScotT]

well I dont get it then...

Ive already seen my DC at 95% and tuner says I need larger?

That comes down to many things.

Your actual rail pressure, the condition of your injectors (what they are flow matched to), the flow of your fuel pump, etc etc.

I was able to fix a similar issue in a GTR running 800cc injectors @ 300kw on a walbro by means of a fuel pump relay. DC is now 70% max.

[joeyjoejoejuniorshabadoo]

what pump?

550's should not be pushed that hard for <300rwkw on pulp

[75coupe]

new bosch 040 pump, & sard 550cc injectors...

[89CAL]

you might have a fuel rich/safer tune then what hamish is running, that wouldnt be all of the reason why you would have such high duty cycle but it would play a part. Along with what others have said.

I'm not a fan of the bosch 040 in skylines for many reasons, but they do flow well enough. Maybe it might pay to do the direct feed re-wire/pump relay anyway

[75coupe]

bummer I can turn spanners but I dont play with wires well....

I'll see what I can do though thanks for the advice... will that change the tune at all..?

[DVS JEZ]

rewiring the fuel pump is easy with R33's or any car that has a battery in the boot. just need a relay and and decent fuse holder with some good thick wire, plenty of DIY info about it.

if you do the rewire and your worried about the tune i can throw my wideband on it and we will go for a little run and check the AFR's

[75coupe]

hey thanks...

if anything it will be richer though, so thats not too bad I guess, would a multimeter of the voltage to the pump help first???

[DVS JEZ]

yep check the volts at idle, after a rewire it should be the same as the battery voltage

[JonnoHR31]

i run 555cc injectors and with the same turbo/engine on e85 i make 325rwkw with a DC of 92%

you'll just squeeze in

your cars a freak tho when it comes to inj d/c. most people wont be able to do that on e85

for example, my cars probably at the other end of the scale, i have the same injectors as you and run about 90-95% at around 260-280rwkw on PULP

[89CAL]

what fuel pump is that with?

[joeyjoejoejuniorshabadoo]

nismo intank pump and nismo injectors.... stock fpr

[JonnoHR31]

044 hardwired, nismo 555s and tomei reg with a tiny pressure increase for me.

Edited December 6, 2010 by JonnoHR31

[joeyjoejoejuniorshabadoo]

weird.... what other factors can influence dc?

[DVS JEZ]

can the settings in the ecu affect DC?

one GTR i was tuning maxed out of adjustment on the 20x20 grid while using datalogit and i couldnt get it any more power due to the lack of fuel/inj duty,

BUT

I tried something sneeky and adjusted the value's of the stock injectors to 115percent and left teh lag time at 0 and straight away i had heaps of room to tune with, gained an extra 25kw from stock inj 312.9kw stock RB26 N1 turbo's and poncams stock inj etc

[89CAL]

That's interesting....

JonnoHR31: How often do you see the high Inj Duty (90% +)?

[JonnoHR31]

weird.... what other factors can influence dc?

D/C vs power can be influenced by heaps of things including fuel type, fuel pressure, injector condition (flow and latency), richness of the tune, ignition timing (which can be influenced by size of turbos, exhaust, intake, cams etc etc) and different dynos.

89CAL, everytime i hit full load at high rpm

[Deano 1]

mine hit 100% on high boost.... have been running it like that for 2-3months now, ive got a set of sard 700s just havnt installed em yet. but it hasnt been a prob, ive been checking over the plugs after sprinted drives on high boost just to see if they changing colour at all... so far so good. tuned for 11.0afr wot so its pritty fat away

[DVS JEZ]

its not tuned that rich deano, bout 11.3-11.5 this reading is before the cat

[75coupe]

is boost control 'gain' the same as 'duty cycle' on the powerFC boost control settings???

[GTScotT]

Essentially, the boost control solenoid has an open or closed position.

Closed position is controlled by gain. The higher the gain the longer the solenoid stays closed and allows the turbo to 'spool'.

Open position is controlled by duty. The higher the duty cycle the shorter time the solenoid lets boost through to the wastegate, being open allows the turbo to vent exhaust gas and drop boost.

Keeping these points in mind, a common fault in tuning is setting a high gain to acheive target boost as quickly as possible, yet have boost drop off in the higher RPM. Obviously based on the above the best way to tune would be to start with a low gain and work your way towards target boost by upping the duty cycle.

You will also see some boost controllers with a 'start boost feature', this feature is what the minimum boost should be before the soldenoid does anything at all (other than stay closed). There are also others that have a gain and boost setting, these have a map inside that calculates its own duty cycle based on pressure at the sensor.

Having one with start boost, duty and gain with limiter type correction also would be best. Not sure what the PFC has tho. With the above in mind you will probably also see the beauty in the turbotech design