5.3 turbo with 3 bar SD backed by a 4L80e that ihas a Jakes D1 trans brake and control box for manual shifting so it is not connected to the PCM. I have a convertor that stalls at 2800 rpm on the brake and about 118 kpa. It will creep to 3100 after about 10 seconds on the brake. I have tried several things to retard timing (I have an MSD two-step) and I have tried the following:
1. Set trans as 4L80e and no PRNDL
2. Set to non-electric auto trans and P/N switch
3. Installed a resister in the IAT circuit that triggers 25?F when on the brake
4. Set the high and low octane tables to have -16? in the cells I am on at 2400-3000
5. Set the park table to -24? in cells below 32?F and raised multipliers to 1 in those cells.
6. Ground pin 34 on the blue connector to signal trans is in Park.
in the attached file, I see the base timing as expected at -16? and the idle table at -24? but the SAE timing remains in the positive numbers no matter what I do... what am I missing? It's on 93 octane with ID 1050x injectors and an LS1 intake; generally runs great, pulls hard to 6800 at 18-20 psi with a VS racing next gen 78/75, I just can't build boost on the brake and before I go to a loose convertor I wanted to try retarding the timing...
I did delete the MAF sensor channel after the attached scan but haven't been able to run another scan yet to see it that changes anything.
I took the minimum spark- spark retard limit negative and have tried setting every table to negative but it still never drops below about 3? to 4? on the brake.
The area in your log doesn't line up with commanded. Cyl airmass is .8 and up where you have timing set lower. Log shows airmass .68 to .76. RPM isn't quite right, either.
Thing is why isn't the MSD unit overriding the tune like it's supposed to?
Last edited by SiriusC1024; 08-09-2023 at 06:40 PM.
I was anticipating the rpms and cyl/airmass going a little higher like it was doing earlier with 20+ degrees of timing. The MSD 2-step is set to 2800 rpm but with 3-4 degrees timing the mixture went richer and it wouldn't pull past 2400, so it never hit the 2-step. I have the IAT resister on the same button that triggers the two-step and trans brake and I am wondering if I should have it on a separate button so I can ramp up to 2400-2800 rpm with timing and then trigger the retard?
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