Sard 700cc Injector Lag Settings In Fc-datalogit

[saliya]

Hey folks,

well, finally got around to replacing my std. GTR injectors with Sard 700cc jobs.

Did some research and found that the way to do this is replace the injectors, calculate

the new 'percentage' based on the new vs old ratio of sizes, and new lag time based

on old vs. new

They went straight in to the standard fuel rail (using slightly-different o-rings than stock)

edit: these o-rings have the same OD and slightly larger ID than stock, but the stock rings seem to fit OK too.

Jumped in to FC-Datalogit 'Settings 5' and set as follows in Injectors:

Box1 (I presume this is percentage, it's unlabelled)

Old => New

96.4 => 62

96.4 => 62

96.4 => 62

96.4 => 62

97.4 => 63.5

98.4 => 64

Car starts and runs fine on the current map with acceptable AFRs and

just this change only. Haven't made it above 3k RPM nor into boost yet.

Two questions:

Is Box 2 (in Injectors) where the new lag of 0.18ms goes per injector?

edit: YES. Put 0.18 into each box. Running slightly richer all over now, backed off

global correction slightly. Made it onto boost, did some mapping. Oh for a local dyno.

Or, do I adjust the following:

My current INJ Lag vs BatV settings are:

16V 0.604

14V 0.772

12V 0.952

10V 1.132

8V 1.316

6V 1.396

and if so, to what?

edit: No recommendations from anyone yet regarding batt voltage correction, so leaving alone.

Anyone that has these injectors like to share their settings for 'Settings 5' ?

Thanks,

Saliya

Edited September 6, 2007 by saliya

[Richieb]

Hey Saliya,

Strange this, I have been studying the same thing last night, and tonight.

My calculations show that we'd be better with 63 on the injector settings.

I have been trying to work out the lag also, and from where can I glean any info on this factor.

My car was set-up on a Dyno, and is going again on Friday for more of the same, as I have further upgrades etc happening then. Should be finished Saturday pm theoretically. (Going for the magic 400)

I can read the settings from the commander for you if you want?

Cheers, Rix.

[saliya]

Hey Saliya,

Strange this, I have been studying the same thing last night, and tonight.

My calculations show that we'd be better with 63 on the injector settings.

Hey,

Actually, I originally went to 61.1 - the calculations shown in the

FAQ ignore a situation where there is already a correction applied

(which there was in my case).

I think the correction is just applied as a multiplier (i.e. duty cycle is calculated, then

multiplied by the percentage correction factor). So say 10ms is calculated, after

a 62% correction it would be 6.2ms. I haven't done any real logging to see,

and there doesn't appear to be any _definitive_ answer on this one yet.

But if this thinking is correct, then the 'formula' for correction calculation should actually be:

New Correction = Old Correction * Old Size / New Size

So for me, it would be

= 96.4% * 444 / 700

= 61.14% (instead of 62.86%).

I've submitted this for inclusion in the FAQ. I might be completely wrong

(I can't see inside the PFC to see how the correction's applied )

Anyhoo... my car was running a little lean on that setting, so I bumped it up slightly to see what

happened. It's a little richer now, so my guess might be correct... we'll see. Baby steps...

I have been trying to work out the lag also, and from where can I glean any info on this factor.

My car was set-up on a Dyno, and is going again on Friday for more of the same, as I have further upgrades etc happening then. Should be finished Saturday pm theoretically. (Going for the magic 400)

I can read the settings from the commander for you if you want?

Cheers, Rix.

That'd be cool - I'm thinking of creating a database where folks can upload their

PowerFC settings for various combinations of hardware. If you don't mind

sending them to me, that'd be appreciated.

Regards,

Saliya

Edited August 7, 2007 by saliya

[Beer Baron]

no that is wrong. the correction is done from your standard injector size. not from any previous corrections. I can't remember what the response time field looks like in logit but on the HC you just put in the correction from the standard injectors (again don't worry about any other injectors that were previously there). off the top of my head sard 700cc are 0.65ms. you don't need to do all the different voltage values, the PFC should figure that out.

[saliya]

no that is wrong. the correction is done from your standard injector size. not from any previous corrections. I can't remember what the response time field looks like in logit but on the HC you just put in the correction from the standard injectors (again don't worry about any other injectors that were previously there). off the top of my head sard 700cc are 0.65ms. you don't need to do all the different voltage values, the PFC should figure that out.

Hey,

Thanks for your feedback, but I don't see how this can be right.

I know the FAQ says this, but I think the FAQ needs updating

because I believe the FAQ is assuming that there is no correction already applied.

Why is an already-applied correction important? Hypothetically, let's say I have:

* standard injectors

* AFRs which are correct all throughout the rev range

* a correction factor of 63% applied

I chose 63% for the purposes of illustration - I don't know whether it's physically possible

to map an RB26 PFC on std. injectors so that it will run with that much correction -

because it's the correction factor that the formula says I should use for 700cc injectors.

The important part here is that it's not 100%.

Let's say I then change my injectors to 700cc injectors, and I do not alter

the correction factor (I don't need to, because according to the FAQ, it's already correct).

But it isn't correct - my car now runs rich...

So I need to change my correction factor to "63% of what it was before" not "63% absolute" -

see what I mean?

Regards,

Saliya

[Beer Baron]

I understand what you are saying and it's partly correct but what you need to remember is the PFC doesn't know what injectors are in there. all it's calcs are based off what was in the car standard. why your car has those corrections in there I can only assume some of your injectors flowed poorly so the tuner scaled some back. so it pays to always work off a % of 440 CC injectors. (for a GTR). and yeah generally with standard injectors there is no correction already applied but I can see in some cases there may be. to be honest you don't really need the correction at all. you can leave it on 100% and just tune it as needed.

the other issue is, if you had correction applied but sitll using stock injectors then I can only assume it was done so because some flowed badly, but to be honest it doesn't make much sense to me to apply correction with standard injectors, it just should have been tuned better. and the problem you have now is if you are applying correction to the old correction you are carrying over the compensation for different flowing injectors, but your brand new injectors shouldn't have that problem.

[saliya]

I understand what you are saying and it's partly correct but what you need to remember is the PFC doesn't know what injectors are in there.

no, I get that - the injectors are what you tell it they are.

all it's calcs are based off what was in the car standard. why your car has those corrections in there I can only assume some of your injectors flowed poorly so the tuner scaled some back. so it pays to always work off a % of 440 CC injectors. (for a GTR). and yeah generally with standard injectors there is no correction already applied but I can see in some cases there may be. to be honest you don't really need the correction at all. you can leave it on 100% and just tune it as needed.

Also, get that. Sure, you can apply a tune - the idea is with the correction that "the tune you had before" is the same

once the correction is applied. And what I'm saying is that without including the 'before' correction figures,

that just ain't going to be the case. If there's correction applied before (as in my case) it needs to be accounted for afterwards.

As I said before, on the stockers this correction was applied _without_ flow-testing or with reference to EGTs.

I know this because I saw the tune done. And as I said before, all I can assume is that the correction was applied

because of some issue related to the RB26 on cyl5 + cyl6 - according to the correction, apparently they run

leaner than other cylinders because of some other physical characteristic than injectors.

The tune was done by Jim @ CRD before he left, btw.

Regards,

Saliya

[Beer Baron]

yeah that all makes sense. and the correction does make sense too if he wanted to run 5 and 6 a tad richer. I did the same thing on my car except I just cleaned and flowed my injectors and put the two highest flowing ones in 5+6.

[Richieb]

Guys, I think I'm getting alittle out of my depth here.

I am new to the PFC I suppose, and read the writings with interest.

As we are aware, there appears to be very little documentation on the said item in the first place..!

I have to admit that my settings applied by the tuner are way different to the ones we are discussing here as well, I will nip down to my GTR, and write them in next posting for all to see, but mine are more like 90+ % from memory.

I have a theory based upon what we say about the 5/6 increase though, and that it could be the coolant has travelled further, or the inlet trach distance is longer to these 2 cylinders.

To be honest, neither theorems fit entirely, or it would be staged more accurately I guess.

This "Lag" is what though?, am a little unsure of the significance of it, or what it actually does affect. ( I understand I and V relationship, but at 16v, is this not going to push safe limits of the rest of the car voltage-wise?)

My guess is what I was considering shall we say. I am.. in the furture, considering O2 sensors closer to each individual ex port to actually see what is the plot per cylinder, rather than an aggregate figure that all are equal(we know this is not the case)... anyone done this to the RB26 yet?

Next thing is this.. My car is in tuners tomorrow and Sat for next upgrade, and tuning. New Zorst complete(no cat-back, as causing restriction we feel at present, plus Z32s & filters. So, If I can get to car before it goes in Friday, I will get the before and afters from PFC comm.

I note there is a lot of talk about the "Logit", can someone give me more info on this S/W etc.

Just to summarise here. I get the impression that the correction flat figure is what one applies to correct pulse length on a standard car when one fits larger injectors at a guess. Soooo, if any changes are made, they are improvements on std ecu control.... BUT, as the engine ages etc, we can then apply a little more fuelling to suit changing conditions.

Second thing.. is this lag bit... where is this documented?

Third thing is LOGIT, what where why etc.

I am now beginning to get the concept behind PFC now, and I suppose learning all the time. My guess about the variance is that we will have one hell of a task finding 6 identical injectors, I would like to see this..!!... same I suppose with MAFS too.!

Interesting discussion guys. Forgive the odd bits of ignorance from my side though!

[Beer Baron]

it's well know that cylinders 5 and 6 run leaner than the other 4. and it has been tested using individual wideband sensors in each manifold runner. the reasons are 2 big ones. the same of the plenumn chamber means 6 and 5 get more air than 1-4. also being an in-line 6 it has quite a long fuel rail which with a reg at the front (cyl 1) means the cylinder at the back can run a tiny bit down on pressure. also 5+6 are known to run hotter which means that their detonation threshold is lower than the front cylinders so a little extra fuel in 5+6 is some insurance against detonation. saliyas tuner applied that RB26 knowledge when tuning his PFC.

lag time is the response time of the injector measured in mili-seconds. it's different at different voltages as the injector can be opened and closed faster with more voltage.

logit is http://www.fc-datalogit.co.nz/ it is a box and some software that allows you to interface your laptop with your Power FC for tuning.

finding 6 injectors that flow the same is not hard. you can flow some up untill they flow as much as the ones you are comparing with. I've had a few sets tested now and there is not much variance, especially if they are brand new.

[Richieb]

Ah, as I postulated then, length of/distance from inlet or control device causes this phenomena then.

Would it not be wise idea to stage from one end to the other therefore?

If a external FPR is fitted, then would this alter effects a little, or accentuate it more?

Another here is, or is it a known thing that cyl probs can, or are more likely to occur on the back cylinders therefore?

Software. Is there any "Mileage" in the likes of myself purchasing it, how could I benefit in reality?

Injectors. You say there is a variance no less, could this be sorted out by adding a % increase or decrease, if so, how would one account for this?

Sorry to be a pain, but I got the GTR bug bad, and I am now trying to get to grips with it a little more.

[Beer Baron]

it's not the distance that causes it, it's the shape of the inlet. and most people agree there is no need to stage them all, it's purely 6 and to a slightly lesser extent 5 that are most affected. again, it's not a linear distance thing. is the shape of the inlet directing more air into 5 and 6.

exteral FPR wont make any discernable difference. fitting an aftermarket fuel rail and splitting your fuel feed so that you have a feed in each end and the reg take off the middle will even it out.

it's a know thing that 5 and 6 are more prone to problems in an RB26. as I said it's a combination of things (more heat, more air flow, less cooling, less fuel).

the software is only of any benefit if you want to tune the car yourself, or if you want to do some datalogging. most tuners in Aus that tune Power FC use this software so if you are getting the car tuned somewhere it's probably not worth buying it.

yes you can sort out the injector variances using the compensation. simply have your injectors cleaned and tested. they will give you the flow figures in CC/Min at a given pressure. if all flow 420cc but one is 440cc then you would leave 5 on 100% and trim the other one down to 95%.

[Adriano]

If 5 injectors flow 420cc, and one flows 440 then there is something seriously wrong. Also it wouldnt be possible to tune a car with standard injectors and 63% correction, there just isnt anywhere near enough scope in the main fuel table to get aroung the leaness. Usually you have to have the correction pretty close, or you run out of adjustment in one way or the other in some part of the map. With 550cc inj i ran 80,80,80,80,80.5, 81.5. The othe rproblem is that this difference in correction occurs at all revs/load, so although the problem with fuel rail/inlet manifold design only occurs at high airflows, the correction ;occurs everywhere even at idle.

[JimX]

Slightly unrelated question - Saliya, where did you get the O-rings from, and is there a specific size and/or part number? I have the same injectors sitting on a shelf waiting to go in, I was going to re-use the old O-rings or purchase new ones of the same size but after reading your post I think I'd rather get the correct sized ones before starting this job.

[si]

Get yourself a set of new nissan o-rings. That's what i used on my 700cc sards and they went in fine.

[Penfold]

Heres a document that I got from AP engineering site with recommended corrections:

http://members.iinet.net.au/~ptv/injectorcomp.rtf

Hope that helps,

Pen

[saliya]

Slightly unrelated question - Saliya, where did you get the O-rings from, and is there a specific size and/or part number? I have the same injectors sitting on a shelf waiting to go in, I was going to re-use the old O-rings or purchase new ones of the same size but after reading your post I think I'd rather get the correct sized ones before starting this job.

Hey,

Got the O-rings from a mate at Pirtek; he just looked at the new injector and the hole it was going into and sized them to suit.

The new ring is a little thinner than the stocker - it has the same OD but a slightly bigger ID. No idea about part # unfortunately.

I would _definitely_ get a few spare o-rings - it doesn't take too much to slice a tiny bit off one and then you need to throw

it out. I pulled one of the injectors back out and while replacing it gave it a little too much wellie - sliced a sliver off it.

As a result, I found out that you _can_ use an old o-ring (well, there are no leaks so far @ 60psi or so).

I had to use lube and heat the rail with a hairdryer to get it back in, though...

Regards,

Saliya

[SLED]

no that is wrong. the correction is done from your standard injector size. not from any previous corrections. I can't remember what the response time field looks like in logit but on the HC you just put in the correction from the standard injectors (again don't worry about any other injectors that were previously there). off the top of my head sard 700cc are 0.65ms. you don't need to do all the different voltage values, the PFC should figure that out.

Hey Richard, sorry to resurrect such an old thread but I'm hoping either you or a good tuner here can help me out.

I understand the injector correction value from 440cc to 700cc Sards = 63%. The latency/lag appears to be listed as .65ms in most places but .96ms here?:

http://members.iinet.net.au/~ptv/injectorcomp.rtf

Also running Nismo AFM's which have same size body as STD GTR but higher resolution, maybe similar to the 80mm Z32's..........so would I select the Z32 option in the PFC or select "other" & calculate the voltage settings manually.......if "other" do you have a list of voltages to give us a start with.

Thanks in advance for your help.