Nissan ECU Tuning

luk · Joined: 11 Jun 2004 Posts: 93

IMO thats one getho thing to do!
In my point of view its only worthwhile to change your fuel pressure if you're reaching very high injector duty cycle.
Correcting AFR with the fuel pressure regulator...it’s a kid’s thing.

Please don’t take it as an insult Wink

Lew_ecu · Joined: 05 Feb 2006 Posts: 17

Luk

I am not sure if you have followed the conversation.

What I am saying is that Raddy is changing the fuel pressure across the whole RPM range. The ecu, under closed loop conditions will null out what he is doing. It will also know that the fuel pressure has changed and back off the open loop gain for the PWM.

In other words, it gets him nothing. It isn't ghetto. Its just wrong.

The use of a RRFPR should not be compared with these other 'across the board' variable fuel pressure regulators.

The RRFPR is a boost actuated device and will only operate as needed. It never effects the closed-loop operation and therefore effectively works with the ecu. the drivability, economy, emmisions, etc are not effected while the boost AFR is dramatically benefitted.

raddy · Joined: 29 Nov 2005 Posts: 95

Lew_ecu:
but why rising of fuel pressure cured lean mixture at top end than???
it looks like ECU does not change injector pulses, otherwise AFR should be same like before, isnt it?

by the way:
If I rise base fuel pressure to 3bar (from 2.5bar as stock), I should get about 533cc of fuel flow from my 444cc injectors....if I adjust K req. number for 533cc flow, will be fueling correct with lower injectors duty cycle?

datsunboy · Joined: 26 Jul 2005 Posts: 209 Location: New Zealand

yes....thats correct.
you just modify it like you were actually putting bigger injectors in
_________________
1970 Datsun 1600 CA18DET Project

The point of life is not 2 arrive at your grave all preserved & in mint condition, but 2 slide in sideways, scratched & bruised screaming F**K WHAT A RIDE!!

luk · Joined: 11 Jun 2004 Posts: 93

Lew_ecu · Joined: 05 Feb 2006 Posts: 17

by the way:
If I rise base fuel pressure to 3bar (from 2.5bar as stock), I should get about 533cc of fuel flow from my 444cc injectors....if I adjust K req. number for 533cc flow, will be fueling correct with lower injectors duty cycle?

The formula is sqrt(3/2.5). Its not a linear relationship. Its 486cc at the higher pressure

luk · Joined: 11 Jun 2004 Posts: 93

http://www.csgnetwork.com/fiflowcalc.html

a injector flow test would be the best way IMO...but its really easy to find your new k-value, just fill your fuel map with 1's; and tweak your k-value till you get lambda 1 all around.

datsunboy · Joined: 26 Jul 2005 Posts: 209 Location: New Zealand

so luk, when tweaking your k value in this way....
how do you tweak the Void time? ie how do you know when to change it and by how much when your trying to fine tune it from the estimated formula?
_________________
1970 Datsun 1600 CA18DET Project

The point of life is not 2 arrive at your grave all preserved & in mint condition, but 2 slide in sideways, scratched & bruised screaming F**K WHAT A RIDE!!

luk · Joined: 11 Jun 2004 Posts: 93

that formula is for injector flow only.
why do you wanna tweak the void time...if you're using the same injectors?

datsunboy · Joined: 26 Jul 2005 Posts: 209 Location: New Zealand

na.....when changing injectors.....
theres a formula for both void time and K value.....but both ( void more than k ) are really only guestimates, and should be fine tuned.....

I have 440cc injectors...have changed the void and K.....but want to tune it properly....
_________________
1970 Datsun 1600 CA18DET Project

The point of life is not 2 arrive at your grave all preserved & in mint condition, but 2 slide in sideways, scratched & bruised screaming F**K WHAT A RIDE!!

luk · Joined: 11 Jun 2004 Posts: 93

Actually Void time (injector lag/latency….call it what you want) is far from being a guesstimated value….if you use search you’ll realize that.
And as far as I know there isn’t any formula to guesstimate the injector latency…because that is really impossible to achieve, different brands of injector have different opening times….and the size isn’t the only thing that matters.

And as for K-value there is a formula to guesstimate, but K-value isn’t really a linear calculation.

Lew_ecu · Joined: 05 Feb 2006 Posts: 17

Since I have an extensive background with electrical motors, I wonder if injectors can vary as much as motors do.

I suppose using an oscilloscope to look at each injectors rise and fall times as a function of RPM could be used. A very good average could then be achieved. If you had a V6 and you had 8 injectors, you could match the best 6 for closeness (assuming that you have had them all flow tested closely enough also).

datsunboy · Joined: 26 Jul 2005 Posts: 209 Location: New Zealand

the only injector latency formula I have is the one from the VG30 ECU tuning site ( www.tripod...... ). and he saysy on there that its not quite right.

other than actually KNOWING the latency to begin with, is there not any other way of getting it? ie a formula.

and when changing this number up and down while tuning, how does it affect the running of the engnie? is it manily for a smoother idle? or nothing to do with that?

I know different size/manufacture means different latency.....Im just trying to figuree out how to optimize this value when I dont know exactly what it is meant to be.
_________________
1970 Datsun 1600 CA18DET Project

The point of life is not 2 arrive at your grave all preserved & in mint condition, but 2 slide in sideways, scratched & bruised screaming F**K WHAT A RIDE!!

luk · Joined: 11 Jun 2004 Posts: 93

That formula in ztechz.net makes no sense.

http://ecu2.forumwise.com/ecu2-thread540.html&highlight=latency

http://ecu2.forumwise.com/ecu2-thread1146.html&highlight=latency

this threads are very informative

anyway if I were you I would stick to a good known void time for that particular injectors…if you know what I mean Wink

datsunboy · Joined: 26 Jul 2005 Posts: 209 Location: New Zealand

hmmm ok.
I have just tried searching the net for a bit, and cant find a commonly used latency for DSM 440cc injectors ?
I did find a post on this forum that said something about a PDF with a table of commonly used latency times....but the PDF was no longer there to download.
_________________
1970 Datsun 1600 CA18DET Project

The point of life is not 2 arrive at your grave all preserved & in mint condition, but 2 slide in sideways, scratched & bruised screaming F**K WHAT A RIDE!!