Updating LS2 tune (E67) with stock LS3 Injector Data, but x axis values are different

[RocketRod]

I have a 69 Camaro with an LS2 behind a 4l70e out of a 2008 TBSS. Originally we slightly modified stock 2008 TBSS base tune adjusting the shift points, power enrich, ve and spark tables. The vehicle ran fine for several years like this, but the go fast bug bit me and I recently installed cnc ported LS3 heads, new cam (227/235 .640/.647) and a stock 2010 Camaro SS intake/injectors. Surprisingly, even with the upgrades the motor idles and runs well with the original tune, but I know the tune needs to be updated before I drive the vehicle much.

I started to update the injector data and grabbed a copy of a stock 2010 Camaro SS with automatic base tune, thinking I could copy/paste the Injector Flow Rate vs Pressure Delta & Injector Offset vs Pressure Delta vs IGNV table values into the corresponding LS2 tables.

However the range of values on the x-axis are different. Both tables have 33 columns, but the LS2 x-axis goes from 18.6 to 92.8 and the LS3 x-axis goes from 18.6 to 111.4. Comparing the x-axis on both tunes there are 7 column header values that match. Do I just take the columns that match and plug the associated values into the LS2 tune, then interpolate the rest of the values? This seems logical to me, but then I'm a newbie when it comes to tuning and don't want to find out the hard way that I am wrong. I am going to copy/paste the Pulse Width Adder table from the LS3 to LS2 tune since the x-axis values are the same.

I have attached a copy of my tune and the 2010 Camaro SS tune I downloaded from the HP Tuner repository. Any help with this, or other suggestions on next steps (tuning) would be appreciated.

[Eaglegoat]

Give me a little bit. I'll whip something up for you. I gotta get on my computer.

[schpenxel]

Excel, graph, best fit, equation, plug in break points you need.

[MikeOD]

A lot of that data isn't used anyways.

Think about this...you've got 58 PSI in the fuel system, static...doesn't change with boost...so at full throttle, in an N/A engine, the lowest pressure delta you'll see is 58 PSI...now...deep decel, high RPM, lift off the throttle, the engine pulls as much vacuum as it can...lets assume it can make a perfect vacuum in the plenum...so that essentially translates to 1 less atmosphere in the plenum...or 14.7 PSI...so the pressure delta across the injectors is 58 + 14.7 = 72.7 PSI. So since you don't have boost, the pressure delta will never go lower than 58, and since you don't have higher fuel pressure, it'll never go higher than 72.7 (you'll notice in some cars, GM only has that much of the IFR table sloped correctly...after that they didn't bother to touch it).

In fact...since this is a swap into an older car...are you running a return style vacuum referenced fuel system? If you are, then the pressure delta should ALWAYS be 58 PSI. If that's the case, you want to actually make the IFR table 100% flat...you'd want the correct data for 58 PSI in every cell in the IFR table and in the offset table. If you want the EASIEST solution to that...adjust your fuel pressure regulator to 59 PSI with the pump on and engine off instead of 58...then set the entire IFR table to 42.1, and copy the offset table from the 59.2 PSI column of the Camaro file into every column of the other file. If you're running returnless (always at 58 PSI), you should do as schpenxel said above, pop it into excel, best fit an equation and pop it back out.

You can directly copy and paste the short pulse adder table over from one to the other, and the minimum injector pulse table is already the same.

[MikeOD]

Also...IFR is going to be linear (at operating pressures). You can copy the value from 41.8 PSI from one file to the other, (35.4), then copy the value from 76.6 PSI over as well (47.9), then just highlight between the 2 and click the "Interpolate between horizontal bounds" button...that'll fill out enough of the IFR table to cover operating ranges...if you want the part of the table that doesn't matter filled out too, you can show the graph and just make the rest of it linear too (just click the points and drag them up and down).

You can do the same thing with the offset table...it's close enough to linear. Copy the 41.8 PSI column, copy the 76.6 PSI column, and then interpolate between horizontal bounds the entire table...usable area done.

[Eaglegoat]

As promised.

RocketRod.xlsx

[RocketRod]

Also...IFR is going to be linear (at operating pressures). You can copy the value from 41.8 PSI from one file to the other, (35.4), then copy the value from 76.6 PSI over as well (47.9), then just highlight between the 2 and click the "Interpolate between horizontal bounds" button...that'll fill out enough of the IFR table to cover operating ranges...if you want the part of the table that doesn't matter filled out too, you can show the graph and just make the rest of it linear too (just click the points and drag them up and down).

You can do the same thing with the offset table...it's close enough to linear. Copy the 41.8 PSI column, copy the 76.6 PSI column, and then interpolate between horizontal bounds the entire table...usable area done.

Thanks. That's basically what I did.

As promised.

Thanks!

I got the same IFR values, but I have just been slammed at worked and haven't had much time to mess with this.

From what I have been reading my E67 ecm doesn't like the gold plated throttle body, which is what I have. I have been driving the car for ever three years this way. Would it help that much converting to a silver blade, or can you work around this in the tune?

[Eaglegoat]

Thanks. That's basically what I did.


Thanks!

I got the same IFR values, but I have just been slammed at worked and haven't had much time to mess with this.

From what I have been reading my E67 ecm doesn't like the gold plated throttle body, which is what I have. I have been driving the car for ever three years this way. Would it help that much converting to a silver blade, or can you work around this in the tune?

If it's working for you I wouldn't touch it. If it becomes a problem then address it.