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Interesting thread, thanks to all involved. I am on LS1B COS2 (01290002), so only have B3702 (and B3703) to play with. Conversation seems to have centred on later OSs with B120x (for understandable reasons), but is anyone able to confirm the LS1B tables are indeed in reference pulses (mS vs. milliseconds) as Gelf postulated back on page 9? This seems to tally up with the HPT people, and the 5.55 number that keeps cropping up. It also seems a better (more apt) unit than milliseconds.
For the stock LS1 (2004 Monaro) cam I have:
IVO IVC EVO EVC
377.5 574.5 140.5 347.5
And my cam:
361 583 129 355
So I assume if I want to set injector end to IVO, I want to advance 16.5 degrees, so subtract 0.183 from B3702. If anyone could sanity-check it would be a great help :)
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I think it's correct, subtracting 0.183 advanced EOI 17 degrees in my spread sheet calculator, I'll post it later
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After reading all of this again, especially the logic of the quoted section on the previous page, are we advancing the Injector timing or retarding it from 490-220 in the E67? I have a much larger cam now in a 427. It only opens 3* earlier than my previous cam but now has 21* of overlap instead of the 10* I was dealing with. I can see where with a large overlap period hitting the valve after it opens some could be beneficial. I am having a very hard time leaning out my VVE table far enough to compensate for my -LTFT's which to me says I am running rich not lean. Now I just confused myself. Crap. I am going to have to put it in Open Loop and start messing with just injector timing to see what I get for AFR's. Then I guess go back and adjust everything again to get it back to stoich.
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Here is what I ended up doing and it worked great for my build. I used injector base pulse width at idle vs. my cams seat to seat timing to find my new EOIT. I took out my degree wheel and input the .050" and .002" numbers for my stock cam and my current cam. This was a serious eye opener. The stock cam has -16* of over lap at .050" but 0* at .002". Then I input my cam. It has 21* at .050" and IIRC 73* at .002" This made me realize that I was advancing it no where near far enough to actually get the injector to fire prior to the intake valve opening. The small adjustments I was doing was still firing into an open intake valve since I was using .050" numbers to get my injector advance calculations. Next, I checked my IPW at idle which was 1.85ish ms at 900rpm. That data was invaluable to me. I used it to calculate how long it took my injector to fire in crank degrees which is 10*. I had no way to check how long the stock injector takes to fire. But I can only guess that it was around 20* or so since the stock EOIT is 5*ATDC. So I advanced my EOIT 43*. This put my EOIT right at where my intake valve starts to actually open. My idle and low rpm driving improved substantially. The car doesn't buck above 1,200rpm now. I am also averaging 18mpg and getting around 25mph at 60-70mph on the highway. Mind you this is in my 3.73 geared 07' 4,100lb CTS-V with a LS3 427 with ported LS2 heads, 21* overlap cam, ported stock intake and stock cat back. I am also running 52lb injectors. I will say that I have done a bunch of VVE tuning and my MAF is lined up properly. I don't see much over +/- 2 LTFT's. I still have some work to do in the fueling department and I haven't touched dynamics yet since I don't have a good grasp on it yet.
Mike, wish I could have met you a couple weeks ago when I was down in Atlanta. I stopped by and finally me Ron after eight years of dealings and checked out the shop. I was hoping we would be able to talk some tuning face to face but you were on vacation. Maybe next time.
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PRAY,
My name is Christian, I just happen to work with Mike... :) but i'll send him your regards... And yes... he was on vacation and pretty much NO communication... I think he forgot his name during that week...
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Okay, thanks. Sorry about that, I was confused by the end of your post.
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These spreadsheets...is the injector really firing this early at lower temps? am i reading this right?
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That's the data from the PCM
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SPY2520
They do this to "Preheat" the fuel on a cold engine. This allows the fuel to evaporate on the back of the valve because it is the warmest thing in the airstream at those temps!!
You also have to remember the amount of fuel that is being commanded at those levels, just look at your Open Loop Fuel and cranking fuel tables.
It's still an engine and if you aren't evaporating the fuel, it has to be done with a larger amount of the mixture.
It also aids in Catalyst light off, low timing, high amounts of fuel, and you make the first thing to be warm!
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So i have read through this entire post a couple times now and I am still lost on how the spread sheet actually works. Can someone please help me clear this up?
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