What is it? I know it is some sort of function for change in voltage for change in load. But which load, the car load, the injector load?

I am trying to get my injector offset curve for my 30# dialed in correctly (Thanks ChrisB for the Ford SVO offset data). I have a pretty good curve now by making adjustments according to g/cyl and LTerms, but would like a good explanation of what Injector Offset is.

Thanks <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />

 

I would also like to know the definition.

 

Anybody, anybody, anybody....??

<img border="0" alt="[guns]" title="" src="graemlins/gr_guns.gif" /> <img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" />

 

Injector offset is the amount of time for injectors to pass the transtional stage. Otherwords injector closed-to full open amount of time this takes. This is usually set up by a mfg. for a specific application at a general voltage & a specific fuel pressure. Then a pcm has a better understanding of true seqential fuel injection & getting fuel there in right time & quantity especialy at high rpm.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by wrencher:
<strong>Injector offset is the amount of time for injectors to pass the transtional stage. Otherwords injector closed-to full open amount of time this takes. This is usually set up by a mfg. for a specific application at a general voltage & a specific fuel pressure. Then a pcm has a better understanding of true seqential fuel injection & getting fuel there in right time & quantity especialy at high rpm.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Do people really adjust this? Or do they leave it stock? Seems like something that would be difficult to really know.

 

Getting this curve dialed in as closely as possible makes alot of the other tuning easy.

I recently changed to SVO 30#. The stock injector offset curve really doesn't work for these injectors. The car was pig rich in the lower loads, but starving lean in the higher loads. I knew that my a/f ratio was dead on prior to the new injectors, and injector scaling can be calculated exactly. Soo, the only thing left was the injector offset.

I obtained the SVO curve from ChrisB's website and went to work.

Here is what I have found. Whether you want to do it this way or not. I drive my car around in part throttle (because that is where the O2's are accurate) for about an hour with various loads and conditions. The rush-hour drive to work nets some good data. I then compile this data (deleting all 0 throttle conditions) and place it on a scatter chart lterms (average) vs g/cyl. This gives me a representation of where the car is running lean and rich. I then extract a trendline, and the formula for that trendline. The trendline represents a rough percentage correction that has to be made along the injector offset curve (g/cyl gets overlaid as the load). I multiply the separate columns of the injector offset curve by the trendline correction factor and walla. It isn't dead-on. I still have to manually correct some stuff, but the car now runs with the same Lterms and a/f ratio at WOT that it did before.

Wrencher, thanks for the definition.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Any chance you'd like to save us some work and post what you've come up with so far (as a starting point for me and others)?

 

me too.. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

 

Sure, I have no problem putting the data up. I am going to check the data after putting a few miles on the car (a couple trips to work and back) just to make sure it sticks and works properly. I will post the information up before the end of the week.

<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by sross:
<strong>Any chance you'd like to save us some work and post what you've come up with so far (as a starting point for me and others)?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I second that.

 

i have an offset curver made for svo 42#ers but havent uploaded it yet because that is gonna take forever. i can email it to anyone if they like, but id like a copy of the .ls1 file they write it to so that i can copy that into mine <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

 

All svo offsets are for a ford & there pcm's not the same especialy at different fuel pressures.

 

I wonder hoe many people have really spent much time looking at the injector offset tables or the design of the injectors.

Not spending much time on this but I took F-body, base C5, Z06, mixed stock and have mods and 2 using SVO 30 injectors using the stock offset for their model year and using same offset row for each and as can be seen they are sitting on top of each other even though 97 and 98 used multec I and the others are multec II design lined up using same stock offset values except at zero load the older ones are a bit slower at the low end but then equal the multec II all the way through PE.

<img src="http://teamzr1.com/temp/injoffset.gif" alt=" - " />

People farting with this table are walking on a live bomb.
Guess what happens when someone sets the delay incorrect and the injector is coming on too early or late of sparkplug firing ?

Being that table starts in milliseconds and by PE is microseconds, there is zero reason to play with those values esp since the internal coil ramup time esp on multech II were designed to react faster then older designs did.

The SVO #30 is NOT made by Ford, they are by Bosch, the same vendor who makes the injector for the LSx engines and have the same coil specs.

DOwn the road people cocking with this table may see piston or head damage from out of timing injectors firing at the wrong time.

I've seen countless LSXs using the SVO;s with great performance and all maintained the stock injector offset tables.

<small>[ September 05, 2002, 10:34 PM: Message edited by: Team ZR-1 ]</small>

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> Guess what happens when someone sets the delay incorrect and the injector is coming on too early or late of sparkplug firing ? </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">John, in your reference to injector offset, you mentioned setting delay. Is a timing change due to differences in injector open and close? Could you give an example of a proper application (theoretical of course) for using injector offset tables?
Thanks much,
Richard <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

I agree with ZR1...to a point.

I just took the time to overlay my curve (the one I have been working on for a week) onto my old stock curve, and they are almost identical in the 7.5 to 16 mvolt range

However, the stock curve for the lower voltages results in excessivly rich conditions at very low throttle conditions. (Maybe this is where the "older ones are slower" come into play)

I agree that the stock curve is probably the way to go for Mv above 7, but expect to see LTerms around the -15 anytime you are putsing around at low throttle/rpm.

Just my .02

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Team ZR-1:
<strong>I wonder hoe many people have really spent much time looking at the injector offset tables or the design of the injectors.

Not spending much time on this but I took F-body, base C5, Z06, mixed stock and have mods and 2 using SVO 30 injectors using the stock offset for their model year and using same offset row for each and as can be seen they are sitting on top of each other even though 97 and 98 used multec I and the others are multec II design lined up using same stock offset values except at zero load the older ones are a bit slower at the low end but then equal the multec II all the way through PE.

<img src="http://teamzr1.com/temp/injoffset.gif" alt=" - " />

People farting with this table are walking on a live bomb.
Guess what happens when someone sets the delay incorrect and the injector is coming on too early or late of sparkplug firing ?

Being that table starts in milliseconds and by PE is microseconds, there is zero reason to play with those values esp since the internal coil ramup time esp on multech II were designed to react faster then older designs did.

The SVO #30 is NOT made by Ford, they are by Bosch, the same vendor who makes the injector for the LSx engines and have the same coil specs.

DOwn the road people cocking with this table may see piston or head damage from out of timing injectors firing at the wrong time.

I've seen countless LSXs using the SVO;s with great performance and all maintained the stock injector offset tables.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Interesting info ZR1, and I like how you actually have some graphs. But I'm alittle lost, what does the mV in the x axis mean? Is that the voltage to the injector?

And you have the plots for the 30# SVO injectors in the graph, how do you know that those are properly tuned? I guess my question is what criteria did you look for to be able to say, yes, this is the correct offset?

 

NoGo: I'm experiencing the exact problem you are describing. LTRIMs are high at low TPS and idle.

I also looked at Chris B's spreadsheet and the curve fit solution produces some strange results in the portion he extrapolated (i.e. below 6mv). Until 6mv, all the value chages are positive and follow a pretty consistent pattern. However in Chris's model, the 5 and 5.5 mv calculated values result in negative value changes.

I'd like to know the average change you computed from 8mv and lower and see how that compares with Chris B. I'm curious if this is a case of a the pitfalls of non-linear extraplolation or if there are real performance differences here.

To be safe, I was thinking of only modifying values in the 4.5 - 6 mv range on the table. If this gives me no comfort, I'll just play with the MAF curve and fix it that way.

 

ttt

 

I will email you the curve that I have been playing around with.

This is the curve that I have been trying to get dialed in using Lterms and g/cyl.

Coincidentally, it differs from the stock curve in the 4.5 to 7 mv range. Here I have dropped the curve significantly to compensate for the poor LTerms.

The curve isn't perfect, I haven't been able to extract values that represent the very low portion of the curve (4.5 to 5 mv) so those points are a result of the trend corrections. I suspect that these points should be somwhere around where the stock curve is.

I still experience negative LTerms when I let off the throttle, but all other Lterms are near 0.

 

CC me please?