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 Post subject: New injectors tuning
PostPosted: Tue Mar 15, 2011 10:16 pm 
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Joined: Fri Mar 12, 2010 10:19 am
Posts: 123
I'm installing new larger injectors & I need to know what areas of the rom need to be tuned in order to have them work fine. The injectors are: RC-1000cc (PL4-1000), after emailing RC for scaling/latency figures, they sent me latency numbers:
10v 1.17ms
11 0.95
12 0.80
13 0.67
14 0.56
15 0.46

But how can I insert 6 sets of latency values while my rom version (08 EDM) contains only 5 latency slots? Also, RC said that they don't offer a scaling value for the stock ECU, how can I figure out an accurate scaling value for a given fuel pressure?
I know that tip-in-enrichment needs to be changed in proportion to the new injector scaling, which of tables under tip-in do I need to change.
Other than the above, do I need to tune any further tables?


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 Post subject: Re: New injectors tuning
PostPosted: Wed Mar 16, 2011 1:15 am 
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Joined: Wed Nov 22, 2006 10:23 pm
Posts: 2306
Look at the differences from each voltage to the next... you could remove the 14v value and it would make hardly any difference at all. Note that you can change the voltage values for each of the cells in the latency table, so you could just plug in the rest of the latency voltages and times.

In theory, all you need to change is the injector scaling and the tip-in. 1000 seems like a reasonable place to start for the scaling, if you can't find any first-hand experience that suggests another value would be better.

In reality you're almost certainly going to need to do some testing and tweaking to find the optimum values. For idle and cruise, you could probably get into the ballpark by just looking at the fuel trims in Learning View. I have a how-to thread that explains that in more detail.

You pretty much need a wideband to verify that your AFRs are reasonable under boost.

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2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: New injectors tuning
PostPosted: Wed Mar 16, 2011 9:25 pm 
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Joined: Fri Mar 12, 2010 10:19 am
Posts: 123
NSFW wrote:
Look at the differences from each voltage to the next... you could remove the 14v value and it would make hardly any difference at all. Note that you can change the voltage values for each of the cells in the latency table, so you could just plug in the rest of the latency voltages and times.

In theory, all you need to change is the injector scaling and the tip-in. 1000 seems like a reasonable place to start for the scaling, if you can't find any first-hand experience that suggests another value would be better.

In reality you're almost certainly going to need to do some testing and tweaking to find the optimum values. For idle and cruise, you could probably get into the ballpark by just looking at the fuel trims in Learning View. I have a how-to thread that explains that in more detail.

You pretty much need a wideband to verify that your AFRs are reasonable under boost.


Under tip-in, which tables do I need to tune, anything other than 'enrichment A/B'?
Some tuners recommend to rescale the x-axis of each 'per injector pulse width compensation' also in proportion to the new injector scaling, is that needed too?
Could you post the link for that how-to fuel trims thread?


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 Post subject: Re: New injectors tuning
PostPosted: Wed Mar 16, 2011 11:45 pm 
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Joined: Wed Nov 22, 2006 10:23 pm
Posts: 2306
foxbat wrote:
Under tip-in, which tables do I need to tune, anything other than 'enrichment A/B'?
Some tuners recommend to rescale the x-axis of each 'per injector pulse width compensation' also in proportion to the new injector scaling, is that needed too?
Could you post the link for that how-to fuel trims thread?


I'm not familiar with your ROM, but 'enrichment a/b' sounds right. Mine just has one enrichment table and a bunch of tables related to duration and compensation, which I left alone.

Scaling the per-injector tables as you describe sounds better than just scaling the data values, which is what I did... I wish I'd thought of that approach first. :)

This is the thread I was talking about:
viewtopic.php?f=33&t=4899

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2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: New injectors tuning
PostPosted: Thu Jun 23, 2011 9:10 pm 
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Joined: Mon Dec 15, 2008 3:12 am
Posts: 644
Location: Brgy. Horseshoe, The Philippines
scale per injector comp or just zero them out?

viewtopic.php?f=15&t=4029&start=60

viewtopic.php?f=25&t=3004&start=60


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 Post subject: Re: New injectors tuning
PostPosted: Thu Jun 23, 2011 9:47 pm 
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Joined: Mon Oct 06, 2008 8:05 pm
Posts: 616
Location: Broomfield, CO
Scale them. My car idled like crap, constant misfires on #4 when I zero'd out the per-cyl fueling compensations, even though the overall AFR (as measured by the wideband) was right around 14.7. When I put the per-cyl compensations back to stock, then re-scaled the x-axis based on the change in injector scalar my misfires instantly disappeared and idle was smooth as butter.

I think the per-cyl compensations are used to adjust for air flow differences in the intake manifold, which can't be fixed with a global maf scaling. Ideally you would use a 4 channel EGT to actually tune these tables, but I think rescaling the x-axis on the stock tables is a decent start.


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 Post subject: Re: New injectors tuning
PostPosted: Sat Jun 25, 2011 12:44 am 
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Joined: Wed Nov 22, 2006 10:23 pm
Posts: 2306
The per-injector tables in my stock tune have some enrichment in the top-left corner (idle). I figured that was probably a band-aid for having latency set too low, so I could remove that enrichment and increase latency... I couldn't get it work. Tried a few things, and ended up putting them back to stock. It either wouldn't idle right, or wouldn't return to idle.

_________________
2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: New injectors tuning
PostPosted: Wed Sep 05, 2012 12:46 am 
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Joined: Mon Dec 15, 2008 3:12 am
Posts: 644
Location: Brgy. Horseshoe, The Philippines
For those who upgraded injectors, do you all rescale the X axis of the Per Injector Pulse Width comp? How do you go about tuning compensation values per cell?


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