Injector Timing Tool Spreadsheet Help needed for MAX effort 700 RWHP NA LS7

[gtstorey]

What no one here can interpret is what you mean by "severe bucking/surging between 1200-2000 RPM." as compared to your expectations. Or what it's like after "95% of the bucking/surge eliminated!".

[edcmat-l1]

The car never did surge at ~2200 RPM & up...before even addressing the VE table

LOL @ "I'll post a log 2200 rpm blah blah blah"......

2200 RPM is completely different than 1400-2000 RPM where that combo is totally uncomfortable. It isn't even in its happy spot at 2200 but at least it has some air moving through it in one direction.

[88LS7MonteSS]

It's hard to tell but here is a video of the bucking/surging was priot to the ROIT tweaking off idle upon takeoff..don't pay attention to the speedo, it's disconnected right now

[Cringer]

It's hard to tell but here is a video of the bucking/surging was priot to the ROIT tweaking off idle upon takeoff..don't pay attention to the speedo, it's disconnected right now

For the surging, I would suggest:

• You need to fix your VE table, it is rough. It is also rich.
• As already pointed out the spark table needs work too. Since your MAF is failed your ECM is referencing the LO OCTANE table.
• I would also suggest copying over the throttle and spark adaptives from a ZR1 corvette.

Points to ponder:

• Additionally the car is running in open loop...this may be required due to the cam, but I would try to make it run in closed loop.
• The car is commanded to idle at 1,100 rpms, yet the VE table is defining RPM breakpoints from 0, 250, 500, 750, 1000, 1250. This may be required to make the thing start (but then again the cranking VE is 100%...which is not possible for this cam...so that needs to be addressed I suppose), but basically you are limited to 33 columns for the VE table and you are wasting a lot of resolution on RPM areas that the engine will never operate it. I would get rid of the low RPM columns to allow you to add more columns to get you resolution where you need it.

[edcmat-l1]

I don't care what you do as far as tuning you're not going to get that thing to not buck pretty freakin bad in the range mentioned. There's just way too much overlap. You can't tune out reversion. Add in a short runner intake manifold and it only compounds the situation. I'm not saying you can't make it slightly better, especially when the tune is less than optimal, but you're never going to get it to be even tolerable lugging it between 1400-2000 rpm.

About the smoothest you'll make this, running it off EFI is to run it open loop and richer than stoich. But then that creates its own set of problems.

[edcmat-l1]

What's the piston number? Head gasket? Looking for the compression ratio.

And what fuel?

[88LS7MonteSS]

What's the piston number? Head gasket? Looking for the compression ratio.

And what fuel?

Stock LS7 11:1 pistons, 0.040" Cometic, 12.77 SCR, 9.6 DCR. I run pump 91 octane + 16oz TORCO/10 gal for another 4 octane bringing it to ~95 octane. My previous ported LS7 casting heads on the same shortblock/cam put out 680 RWHP using 11.79 DCR & 8.9 DCR on pump 92 octane premium with zero KR.

Thanks for your help!

[GrannySShifting]

So I spent several months this Summer with an oscilloscope testing EOIT and verlon reverse engineered the BIN file. Turns out everything we thought we knew to be correct is false.

I made a video to explain everything and you can download my EOIT tool to tune. All the old spreadsheets are bunk.

https://youtu.be/FmdJOOUUqQg?si=8BhJ-m1O0-3rm5Y9

BTW a cam that big is going to buck. Even worse with a MAF. EOIT won't fix that.

THat cam is not all that big. Solid roller so you can take around 8 degrees off each lobe. Its chunky but not crazy, 2000 rpm shoudl drive decent. Yes for certain dotn waste time with a MAF on that

[88LS7MonteSS]

Another REAL dumb question.....why are my RPM's exceeding the Rev Limiter In Gear settings...seems like my "casual" rowing through the gears almost literally hit 8K RPM rather than shutting down @ 7700RPM???

[07GTS]

id say accel max table needs to be lowered as maxing it out with its ''rate'' may not work, also ur extreme cut is 5692rpm so thats not working either, and ur switchover delay is 5 sec so u have to be in a non working limiter for 5 sec before it will try the next setting, the extreme cut is ment to be above the in gear cut so if the normal limiter cant control it then the extreme cuts fuel, maby having the extreme cut lower then gear cut disables it ?

[88LS7MonteSS]

id say accel max table needs to be lowered as maxing it out with its ''rate'' may not work, also ur extreme cut is 5692rpm so thats not working either, and ur switchover delay is 5 sec so u have to be in a non working limiter for 5 sec before it will try the next setting, the extreme cut is ment to be above the in gear cut so if the normal limiter cant control it then the extreme cuts fuel, maby having the extreme cut lower then gear cut disables it ?

The 5692 RPM was in the original tune...I upped the RPM to do the road testing and it's set to 7700 RPM per the pic above...and stock the limiter is set for 5 seconds and seemed to work fine back then

[ns158sl]

Making HP is the easy part. Making it driveable is the hard part.

Like I already stated, work on your timing table. You can literally see in your first log that it pulling a shit load of timing and adding that back. With that cam, it is going to be extremely responsive to timing. Fueling is still first, but work on that timing. ALL, HO/LO/Idle/Over/Under. I laughed, because I already said to do that. Then I had to screenshot a timing table. Simmer seabiscuit.

[88LS7MonteSS]

As already pointed out the spark table needs work too. Since your MAF is failed your ECM is referencing the LO OCTANE table.

actually I respectfully disagree! If you look at the pic I posted for the RPM Rev Limiter concern, you'll see that the ECM is commanding 28? timing at high RPM (7k-8k RPM), this is the HO table, the LO table is 5? less across the board!

The car is commanded to idle at 1,100 rpms, yet the VE table is defining RPM breakpoints from 0, 250, 500, 750, 1000, 1250. This may be required to make the thing start (but then again the cranking VE is 100%...which is not possible for this cam...so that needs to be addressed I suppose)

I understand and agree but I have to tell you, as is, my car fires off almost instantaneously UNLIKE several of my friends who have almost as large a cam and their cars tuned by TRUE paid PROFESIONAL Tuners this Forum FULLY respects and will go unnamed! I'm not sure I want to do anything to change the way it currently starts....I suppose I can try reducing the VE at start a bit because 100% is unreasonable just to see what happens!

[ns158sl]

ok. So it is referencing the HO table, cool. Everything Cringer, Ed, Alvin, Etc said still stands. Regardless, post another log with an updated tune if you want more help with your ridiculous timing gain/bucking.

[07GTS]

The 5692 RPM was in the original tune...I upped the RPM to do the road testing and it's set to 7700 RPM per the pic above...and stock the limiter is set for 5 seconds and seemed to work fine back then

the 5692rpm is ment to be the extreme cut so no matter what alse is going on it will cut at that rpm, but it is not, raising the gear value on its own will work when the other limiters arnt in play also, raise the extreme cut to 8000 and extreme resume to 7900 rpm see if that then allows the 7700rpm limiter to work, factory do things for factory reasons and ur far from factory so some things need to be done differently, when limiter is active the torque control is active trying to hang onto it so that is in play also as u can see your throttle control source is torque at the limit point, u can also add throttle in the limiter so its not just fuel cut

[88LS7MonteSS]

ok. So it is referencing the HO table, cool. Everything Cringer, Ed, Alvin, Etc said still stands. Regardless, post another log with an updated tune if you want more help with your ridiculous timing gain/bucking.

Latest tune & Scan...unfortunarely now, I'm going to have to get a good drag-radial...almost lost it in 4th gear on the Freeway when the tires broke loose!

[Alvin]

Not all OS's default to low octane in SD. A lot do.

Custom OS stuff will fix the low octane mode default in SD mode.

There is zero chance this will get along in closed loop with narrow band O2 sensors.

[88LS7MonteSS]

Not all OS's default to low octane in SD. A lot do.

Custom OS stuff will fix the low octane mode default in SD mode.

There is zero chance this will get along in closed loop with narrow band O2 sensors.

I have it in closed loop beause I am still tuning the PE EQ...

[blindsquirrel]

Narrowbands don't work when it's in PE. And PE = open loop.

[GrannySShifting]

Wait, you do not have a wideband in this?