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Thread: Noob question Gen V LT1 C7 GS : ignition Timing / AFR with different bolts on

  1. #1

    Noob question Gen V LT1 C7 GS : ignition Timing / AFR with different bolts on

    Hi Guys,

    Sorry for my dumb questions, but I'm a noob...

    I have several issues I'm trying to understand.

    First one is :

    I first installed an AFE CAI and ARH LT headers on my 2017 C7 GS 1 month ago. I bought a wideband O2 sensor to monitor how the car would run with stock ECU program. It was running at 0.89 Lambda at WOT, a little lean. Since the tuner I was planning to use (JDP Motorsport, Salt Lake, UT, HPtuner) was 3 month out for a dyno tuning, I bought Diablosport Intune ( I know should've bought HP tuner, perhaps will do it) just to be able to adjust my fueling to be safe in the meantime.
    I had to add around 5% of fuel at WOT to go in the 0.85-0.86 lambda range.

    Then I installed my MSD Intake manifold last week end. Very strangely (at least for me), with the same tune (stock tune with 5% more fuel) the car ran a lot richer 0.79 Lambda at WOT. I completely don't understand....I had to go back to stock fuel map to go back to 0.86-0.87 at WOT... How it is possible with a manifold that has more volume and flows better ???? When I look at my absolute intake manifold pressure it is the same as barometric pressure....and same or slightly better than stock manifold. My MAF values are a little higher than before ... (around 330-335 g/s at 3000ft, saw a pike at 346 ) It doesn't seem I have a leak as I would run a lot leaner with a leak, my idle is stable, driveability good (though it seems I have lost in throttle response and little torque low)...

    Second one is :

    I completely don't understand how works the timing on this car... Here are 2 datalogin 15 min appart. First i have between 20 (high rpm) and 23 (max torque) degrees of timing ( 91 octane, around 3000ft elevation) . After 15 min of sport driving (mountain road) but with same intake temps, same fuel same elevation, only 12 degree at high rpm and only 15 deg at medium rpm. No knock retard at all.... What the heck ??? The more i was driving the less timing I had it seems... The car felt definitely way slower at the end with low timing...

    Datalog 1.jpg

    Datalog 2.jpg

    Any insight would be appreciated, as I don't understand at all...

    Thanks guys

  2. #2
    Tuning Addict 5FDP's Avatar
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    In short, the entire airflow model and torque model now become incorrect because the intake manifold swap. You will get things like you described happening because it is not calibrated for the changes you have made. You never told the computer that the manifold flows better or creates more power and torque at different rpms, it still thinks the factory intake is still installed.

    These newest computers are very sensitive to changes and are likely not to respond correctly if the changes are not accounted for.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Quote Originally Posted by 5FDP View Post
    In short, the entire airflow model and torque model now become incorrect because the intake manifold swap. You will get things like you described happening because it is not calibrated for the changes you have made. You never told the computer that the manifold flows better or creates more power and torque at different rpms, it still thinks the factory intake is still installed.

    These newest computers are very sensitive to changes and are likely not to respond correctly if the changes are not accounted for.
    Look,based on this video it seems with stock calibration it made 460WHP which is not too bad... exact same config as mine... CAI/LT/MSD .. They tested first with stock tune all mods...

    MSD states their manifold doesn't require a tune...



    But their air fuel ratio stays the same, clearly not the case for me though at the end seems the same than mine...they didn’t go leaner with CAI/headers like mine did...
    Last edited by Sachs; 04-26-2018 at 08:41 AM.

  4. #4
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    You're a fool to believe you don't need a custom tune. MSD may claim they don't need a tune, but that is based on if the ONLY mod you had was the MSD manifold. That would keep things inline enough for the ECU to compensate. Another thing to learn, you can't believe everything you see on the internet, in addition all cars respond a little differently, could be altitude or humidity and temperature.

    Bottom line, get a custom tune. More than just the MAF needs to be adjusted on your car. You can try and reason all you want about why you shouldn't see what you are seeing, but reality is, you need a real tune. Suck it up buttercup.
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  5. #5
    Tuner in Training big_sapper's Avatar
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    I really can't imagine that an MSD intake & LT wouldn't require a tune. I've not heard of anyone trying to run the stock tune with LTs that haven't thrown a lean code.

    Hell, my C7 Stingray with CAI, ported TB, ported stock intake, ported exhaust manifolds and no resonator x-pipe set a lean code and required tuning.
    2004 Black Corvette (A4)

  6. #6
    Quote Originally Posted by TriPinTaZ View Post
    You're a fool to believe you don't need a custom tune. MSD may claim they don't need a tune, but that is based on if the ONLY mod you had was the MSD manifold. That would keep things inline enough for the ECU to compensate. Another thing to learn, you can't believe everything you see on the internet, in addition all cars respond a little differently, could be altitude or humidity and temperature.

    Bottom line, get a custom tune. More than just the MAF needs to be adjusted on your car. You can try and reason all you want about why you shouldn't see what you are seeing, but reality is, you need a real tune. Suck it up buttercup.

    I never challenged the fact that I need a tune I?m trying to have my appointment set up.

    It is just that I?d like to have some explanations of what is going on ( ie how an MSD would make the engine richer after CAI and LT made the engine run leaner...)

    By the way the check engine light says leaner, I?m not lean at all, have a wideband and 0,85 at wot is totally safe.

    And why the timing is moving so much (decreasing) the more I run the car...despite no knock retard...

    By the way the C7 in the video runs on stock tune and puts good number and good afr...

  7. #7
    Tuning Addict 5FDP's Avatar
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    Just because the wideband shows .85 lambda at WOT does not mean it's not lean everywhere else. If the check engine light is on for a lean condition then the airflow model is incorrect causing the fuel trims to do more work than they should to correct the problem. WOT does not use closed loop fuel control. There is way more to tuning than just WOT lambda readings.

    There are too many unknowns here to say why things are happening. You can't provide a real data log with parameters that we normally see with HP Tuners software. This is spit balling here but the intake flows more air, so more airflow means more fuel. The more air the passes through the MAF/Intake the more fuel it would give. Then you also deal with the fact that the airflow model and torque model are now not correct and it can throw the computer for a loop and cause other fueling issues and timing issues.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  8. #8
    Quote Originally Posted by 5FDP View Post
    Just because the wideband shows .85 lambda at WOT does not mean it's not lean everywhere else. If the check engine light is on for a lean condition then the airflow model is incorrect causing the fuel trims to do more work than they should to correct the problem. WOT does not use closed loop fuel control. There is way more to tuning than just WOT lambda readings.

    There are too many unknowns here to say why things are happening. You can't provide a real data log with parameters that we normally see with HP Tuners software. This is spit balling here but the intake flows more air, so more airflow means more fuel. The more air the passes through the MAF/Intake the more fuel it would give. Then you also deal with the fact that the airflow model and torque model are now not correct and it can throw the computer for a loop and cause other fueling issues and timing issues.
    I currently don?t have this fault, though had it once before the msd.
    The engine doesn?t run lean when in closed loop because of the closed loop, i can see it trying to reach lambda 1 on light loads, though i can perfectly understand this ecu has do to more work or go outside its standards values to achieve it.
    And I completely agree there is more than WOT tuning/ Timing/fueling and that I need a tune ...
    In my situation could a remote tuning work provided I have a good datalogging and a wideband ? I still haven?t my appointment setup as the shop I plan going to is overbooked....and I don?t have options in Idaho (Boise)...

  9. #9
    Advanced Tuner lt1z350's Avatar
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    Just tackle it your self. Im sure with tuning the maf and dialing in the virtual torque it will clean right up. You will get help on here and plenty to read. Im not an expert like many on here but could give you a hand too. Even if you just tweak on it to make it better till can get it done on from the shop. Up to you just pm if want some help with it. I learn more every time I do things like this so fine with giving a hand. In the process of doing my zl1 myself now.
    First 9 second 6th gen lt4 zl1 stock blower SHC SBE boost only.

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  10. #10
    Quote Originally Posted by lt1z350 View Post
    Just tackle it your self. Im sure with tuning the maf and dialing in the virtual torque it will clean right up. You will get help on here and plenty to read. Im not an expert like many on here but could give you a hand too. Even if you just tweak on it to make it better till can get it done on from the shop. Up to you just pm if want some help with it. I learn more every time I do things like this so fine with giving a hand. In the process of doing my zl1 myself now.
    Thanks

    Yes I?ll do that. I really think it sould be interesting for me to gain knowledge in this area.
    Now i need to choose which kit to buy. 6011 or 6021 , standard or pro ?

    My wideband is connected to an innovate, but i should be able to use it on a pro. But is it critical to log lambda at the same time or just look at it separately just to double check everything is ok ?

    Another option, what do you think of the remote tuning option from RDP Store ? Or is there another good shop been able to help with remote tuning ?

  11. #11
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    Did you have to set up your wide band with a stoichemetric value? If you?re using normal pump gas with alchohol it?s around 14.1.

  12. #12
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    I know it's been posted all over before, but would you mind showing us how to properly fail the MAF and set up a histogram to dial in the VVE? I recently swapped my manifold and throttle body as well and my torque/air models are all types of f*cked up lol.
    Last edited by HeavyChevy305; 04-28-2018 at 12:05 PM.
    2023 Ford Maverick 2.0T AWD

  13. #13
    I don’t use AFR lambda is more relevant. But for E10 yes stochio should be 14.1

  14. #14
    Just bought hp tuner pro 6021 Will have it Tuesday.

  15. #15
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    As for virtual torque values, for an intake manifold swap I think the torque models theoretically don't need to change, since the torque model is referenced from MAP and MAF values, and if the stock airbox and MAF sensor hasn't been messed with, you theoretically shouldn't have to change the MAF scaling.

    Now virtual VVE will need to be adjusted since this is a lookup type table based on the physical state of the engine itself. Even with something like a cam the torque model should theoretically not be adjusted, but the VVE should.

    Now for something like milled heads for a compression ratio increase, that would need a global increase in the toque tables.

    Am I wrong here?

  16. #16
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    Text me I have exact same car and I have a very good tune for all motor. 281-450-1498.

  17. #17
    Quote Originally Posted by paulsmithsr View Post
    Text me I have exact same car and I have a very good tune for all motor. 281-450-1498.
    Will do when I will receive my HP tuner kit (Wednesday finally) Thanks !

    In fact guys, by educating myself with Youtube and Internet I think I know why my timing decreased this much...

    I think the car switched to the low octane ignition table because I picked some knock retard on partial throttle....So my knock retard learn factor was probably close to 1.0 so fully switched to Low octane table.

    I had some pikes with like 7-10 deg of Knock retards in my recording, not a WOT by at partial throttle... not good

    It would make sense no ?
    Last edited by Sachs; 04-30-2018 at 07:24 PM.

  18. #18
    Quote Originally Posted by paulsmithsr View Post
    Text me I have exact same car and I have a very good tune for all motor. 281-450-1498.
    Can you help me in tuning c7 (2014)