per injector pulse width compensation (32-bit ECU)

a13normal · **Joined:** Thu Feb 14, 2008 5:04 pm **Posts:** 8

Tgui wrote:

ClimberD wrote:

bump to this, wondering whether anyone ever figured anything else out about why Subaru did this.

My bet is that Subaru was attempting to compensate for statistically significant differences in the intake manifold for each cylinder. That and possibly combustion differences as well. Heck maybe there are thermal reasons behind varying the fuel delivery per cylinder. I'd also assume they used some very expensive equipment on a mounted engine to calibrate these tables as well.

Of course swapping injectors throws the viability of these tables out the door, hence why people like me zeroed them out.

This right here makes me wonder if I should zero out my tables if I swapped from Sidefeeds to dark blue top feeds on my FXT. I've literally just copied tables over from my old stock WRX map (where the injectors came from, after all) for flow scaling and latency, was wondering if I ought to zero these out as well.

PS: TGUI I owe you an email!

Tgui · **Joined:** Wed Jul 12, 2006 1:25 am **Posts:** 1025

a13normal wrote:

Tgui wrote:

ClimberD wrote:

bump to this, wondering whether anyone ever figured anything else out about why Subaru did this.

My bet is that Subaru was attempting to compensate for statistically significant differences in the intake manifold for each cylinder. That and possibly combustion differences as well. Heck maybe there are thermal reasons behind varying the fuel delivery per cylinder. I'd also assume they used some very expensive equipment on a mounted engine to calibrate these tables as well.

Of course swapping injectors throws the viability of these tables out the door, hence why people like me zeroed them out.

This right here makes me wonder if I should zero out my tables if I swapped from Sidefeeds to dark blue top feeds on my FXT. I've literally just copied tables over from my old stock WRX map (where the injectors came from, after all) for flow scaling and latency, was wondering if I ought to zero these out as well.

PS: TGUI I owe you an email!

I'd say zero them out. My car *seemed* to run smoother with swapped injectors when these tables were zeroed out.

MFB · **Posted:** Tue Nov 09, 2010 1:57 am

Does zeroing the comp tables affect afr for OL, long term fuel trims ? I have 650cc DW and fall in the swapped out injector category. :-)

I also have perrin el headers.

Other than feeling it smoother, is there a parameter to look at for zero out benefit?

Update:
Ok, just tried this out for a drive around to where Im going. Im assuming whole maf may be rescaled for this. Close loop shows very rich LTFT B. I didnt get the wideband in for OL but Im just going back to stock comps.

phatron · **Posted:** Mon Jan 10, 2011 11:55 pm

FWIW, I zero these out on every car I tune.

I logged AFR before and after on both my WRX and STi and didnt see any difference in Trims or WOT AFR....

Tgui · **Joined:** Wed Jul 12, 2006 1:25 am **Posts:** 1025

phatron wrote:

FWIW, I zero these out on every car I tune.

I logged AFR before and after on both my WRX and STi and didnt see any difference in Trims or WOT AFR....

11 posts, don't like you're a pro. :wink:

MFB · **Posted:** Tue Jan 11, 2011 8:43 pm

Will zeroing this out affect Open loop?

Tgui · **Joined:** Wed Jul 12, 2006 1:25 am **Posts:** 1025

MFB wrote:

Will zeroing this out affect Open loop?

None here can give a definitive measured and backed up answers on this.

Like others, I did think I noticed smoother operation when zeroing out this table while running upgraded injectors. This would indicate fueling changes in OL & CL since this is a base table ultimately referenced in both modes.

MFB · **Posted:** Tue Jan 11, 2011 9:00 pm

Seems I do need to check with wideband just to be sure.

dschultz · **Posted:** Tue Jan 11, 2011 9:01 pm

Tgui wrote:

phatron wrote:

FWIW, I zero these out on every car I tune.

I logged AFR before and after on both my WRX and STi and didnt see any difference in Trims or WOT AFR....

11 posts, don't like you're a pro. :wink:

Check out http://www.romraider.com/RomRaider/Prof ... uners#toc6 the last entry. Ron & Mike.

Tgui · **Joined:** Wed Jul 12, 2006 1:25 am **Posts:** 1025

dschultz wrote:

Tgui wrote:

phatron wrote:

FWIW, I zero these out on every car I tune.

I logged AFR before and after on both my WRX and STi and didnt see any difference in Trims or WOT AFR....

11 posts, don't like you're a pro. :wink:

Check out http://www.romraider.com/RomRaider/Prof ... uners#toc6 the last entry. Ron & Mike.

Thats the joke.

Plus, everything he knows about tuning FP Greens he learned from me. I've known him on other boards for some time. He's probably too big time now to remember, though. :mrgreen:

dschultz · **Posted:** Tue Jan 11, 2011 9:45 pm

Ah, inside joke then....

MFB · **Posted:** Wed Jan 12, 2011 2:57 am

Is it worth all the work to redo Maf table just to zero out per injection pulse width comp and get the "smoothness"?

Tgui · **Joined:** Wed Jul 12, 2006 1:25 am **Posts:** 1025

MFB wrote:

Is it worth all the work to redo Maf table just to zero out per injection pulse width comp and get the "smoothness"?

The injector pulse widths you're changing are so small that you won't need to mess with MAF.

MFB · **Posted:** Wed Jan 12, 2011 3:05 am

Tgui wrote:

MFB wrote:

Is it worth all the work to redo Maf table just to zero out per injection pulse width comp and get the "smoothness"?

The injector pulse widths you're changing are so small that you won't need to mess with MAF.

Ok, just concerned on the negative ltft B I saw when I previously flashed and log with a 0 comp table. I will proceed and see, got a morning drive now worth 1 hr. Im +8 gmt :-)

I should see the same ltft right?

Tgui · **Joined:** Wed Jul 12, 2006 1:25 am **Posts:** 1025

MFB wrote:

Tgui wrote:

MFB wrote:

Is it worth all the work to redo Maf table just to zero out per injection pulse width comp and get the "smoothness"?

The injector pulse widths you're changing are so small that you won't need to mess with MAF.

Ok, just concerned on the negative ltft B I saw when I previously flashed and log with a 0 comp table. I will proceed and see, got a morning drive now worth 1 hr. Im +8 gmt :-)

I should see the same ltft right?

You might see some, but yeah, be safe. Every car is typically different.

RomRaider

per injector pulse width compensation (32-bit ECU)

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