Read halfway down the first page, then skip all the rest and jump straight to the 'post reply' button. This does not bode well for their journey into the world of tuning.
Read halfway down the first page, then skip all the rest and jump straight to the 'post reply' button. This does not bode well for their journey into the world of tuning.
Originally Posted by SiriusC1024
Somebody make this make sense to me. Maybe I'm looking at this wrong, but I'm having trouble understanding the values here. If the fuel supply is regulated with a vacuum reference, then the pressure would change with engine load, and affect the flow rate. If it is being supplied a constant 58psi with no vacuum reference, then the flow rate should remain constant. Why do these data files show it reversed? Am I not reading something right?
You are not reading something right.
The flow through the injector depends on the difference, or Delta, between the inlet from the rail to the exit at the injector tip in the manifold. More pressure at the inlet OR less pressure at the outlet, will make the injector flow more. Opposite is also true, less pressure at the inlet or more pressure in the manifold will make it flow less.
With a returnless system the rail is always 58, but the manifold pressure varies based on load. Therefore the pressure across the injector - the difference between inlet and outlet - also changes which means the flow rate changes depending on the manifold pressure. With low pressure (lots of vacuum) injector flows more, high pressure (less vacuum) the injector flows less. The tables have to reflect that.
With a referenced regulator, the pressure across the injector is always the same - manifold pressure drops and rail pressure drops, manifold pressure goes up and rail pressure goes up. The rail pressure is always 58 PSI higher than whatever is in the manifold. At 20" of vacuum the pressure across the injector is the same as at WOT with 0" of vacuum. Always the same Delta = always the same flow rate. All the columns are the same all the way across.
Ok, thank you for explaining it that way, I did not consider the output side of the injector having pressure working against it. Now it all makes total sense.
Last edited by agolden61; 10-16-2024 at 01:23 AM.
Yes, many people don't know that in the beginning and forget we are living in an average of 14psi of pressure and the delta is a very important part.
When there's one table that uses gauge pressure and another that uses absolute pressure, that still makes my head hurt sometimes. But pressure Delta is gauge/absolute agnostic - it's just the difference between one point and another point.
Snake Eater Performance SEP 1000cc Long - Pro-Series - 1000cc - 60:14:14 - EV6 (USCAR) plug
SEP 1000cc Long.png
dumb question but how to you adjust for columns if the data doesn't match up? the voltage offset. say 08 e38 ecm and the 2010yukon bin. when switching over to 126134412 injectors.
can this be done with the excel file posted? it does look like the tbss file posted back on the first few pages matches up, but would that be correct for a ls3 car? it seems close on the voltage table but others seen off
I have not seen a spreadsheet to convert data from different e38 formats. That would be a awesome thing to have.
Zero out all the tables in the target file, in the donor file 'Copy With Axis', paste, interpolate across any gaps, double-check in graph view.
...or just copy from a file where that's already been done.
Attachment 153528
thanks for that. i had looked thru this one from a tbss that you did. https://forum.hptuners.com/showthrea...l=1#post733292
voltage offsets looks the same but other stuff looks a bit different. i'll load it up tomorrow and see how it runs.
thanks again.
is there any details you guys look for that points to if you have the correct injector data in the right place?
anyway to test? like I have an adjustment alternator out put I could change the running voltage from say battery 12v to 15v and see if the trims change or something?
Are you looking to verify there is a problem, or that there isn't a problem? If it's the first then you're being cryptic for no reason; state the problem clearly and ask how to fix it. If it's the second you're being paranoid.
IN THEORY, if the old injectors are in good shape and the old injector data is accurate, and you tune it, and then you swap in different injectors and different data, and if those new injectors are what they claim to be and their data matches, then the tuneup should need zero changes. If the new injectors are correcting some previous problem it'll need some tuning where you had previously tuned to compensate for whatever the old injectors couldn't do right. If the old injectors were busted and/or their data was wrong and you tried to tune it while it was like that, and then changed injectors, then yeah the whole thing is going to be off.
bit of a long story but yes, old injectors had one bad injector for years that I didn't realize, it read 80ohms while the rest showed 12.8. I tuned it over the years without knowing this and it ran good to me, tuned for 2 different exhaust setups. finally from the help of this board I realized the injector issue. I put a set of stock supposed to be low mileage used ones in. of course the tune was off and to me it idled rougher. since they weren't new, and I had a set of the flex 52s on the way, I went ahead and swapped those in. of course those need tuned too since I don't have a known good base tune, just wondering if there's some way to tell if the data for these is correct before I spend time logging and tuning them? like is there something simple you guys look for. it the data is incorrect, what trouble would that cause tunings around it?
That would've showed up as bank-bank imbalance if you had been doing narrowband tuning instead of that OL wideband nonsense.
Nothing wrong with the data he gave you.
Move along.
I do and did tune using long term trims.. banks looks equal to me. I never graphed it out and watched the replay, just log copy and pasted data since it ran perfectly smooth and was completely stock when I got it. I had to go back and find a old log from 2017 and it was there back then too.
so no, I don't tune the idle and low end stuff with a wide band.
and I have 3 versions all slightly different that have been transferred over. one I found on this site, one provided above and one that I had tried my hand at making up. all 3 are slightly different data, again my question is does it matter, are there any long term issues that might pop up later without perfect data. no need to move on if someone knows the answer to a question that saves me a headache later.
do you know?
You can convert the data yourself easily enough if you don't trust it. Copy With Axis -> paste, then interpolate across any gaps.
thanks. I did that with ecm12307 injector flow rate vs pressure delta. since it didn't look like it lined up with the 2010 yukon one at the 400kpa. seemed a bit lower.
i think I'm fine with ecm 12308 offset vs delta vs ign voltage. the one you posted looks correct to me. the other ones are the ones I question myself on, since I don't know what they mean.
ecm 33392 flow multi vs fuel flow. on my stock tune it's populated with a curve, in the yukon tune it's all 1.0000 across the board. so I copied it over, but I don't know why. do you even mess with those?
same with ecm 7977. stock is 1.0000ms. yukon is 4.0000ms. I left it, but should it?
under injector timing, normal rpm ecm13338. stock has a curve populated and yukon has all zeros. I left stock in there since it seemed like injector timing might be ecm hardware based thing?
oh, what about rail pressure, stock is 400kpa min and max, yukon is 425min 450max. I left 400kpa in there.
boundary looks a little different, but Googled it and it seems to be cam related, so left it stock.
does any of this stuff even matter? would it show up in the tune if I guessed wrong?
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