L31 ECM with 9 PSI boost Help

I need some help, I am new with EFI live and have searched the forums but have not found the answer I need yet. I have a 98 Vortec with a L31 ECM it has 48lb injectors running at 58-62 lbs fuel pressure (60lbs/hour), pro charger @9lbs of boost, and 383 ci @ 9.1 compression. I have changed the flow rate of the injectors to 7.5 grams per sec and the cylinder volume. Do I scale the VE table and use a 2 bar sensor? I am trying not to use the FMU to boost the fuel pressure. I have played with the PE charts to change the commanded fuel ratio to get to 12.5 to experiment. I could use some experienced help here to give me a direction. Thanks!

How much power will engine make with boost...?
Are you running a MAF, and if so, does MAF/PCM have a flowrate limit (512 g/s on some PCM's)...?

Could scale IFR, VE, MAF tables together (and shift down any table referencing airmass or airflow on its axis).

Or could scale IFR by /N and scale Stoich AFR (B3601) by xN.

Thanks Joe! The engine should make low/mid 500hp if my calculations are right. After reading a whole pile of threads I ran out and got a 411 ecm. The engine currently runs a MAF and Map combination, I got to thinking a custom EFI OS and a 2 bar MAP would be the simplest. Your input here is greatly appreciated as I get the understanding from reading all he post that you are the go to guy.

Try COS5 (which is based on OS 12212156).

Yes, you need a 2-bar MAP sensor, be sure to enter the scaler/offset (so that SAE.MAP pid show the correct values in all test cases).

You will run out of MAF... the 0411 (and some other PCMs/ECMs) limit the MAF to 512 g/s...

so you could scale IFR/VE/MAF together (can't really scale IFR/STOICH because you're going to run out of MAF)...

tuners typically end up running SD (without scaling since 0411 IFR max is 512 g/s).

Remember: when you scale VE/MAF you also have to shift downwards any tables that reference airmass (g) or airflow (g/s) on their axis (and this is usually tedious because you can't just copy/past).

Thanks joecar, so the million dollar question is what is the best approach. I do not need to use the 411, is there another option in ECM's that will work for this application that can be used that has a higher MAF limit? I assuming that a MAF tune is easier for a novice like myself.

The best PCM to use is the ones that are compatible with the rest of your vehicle (e.g. ABS)... if they are easy to tune and flash.


It seems to me that the GenIII and earlier PCM's all had a MAF limit of 512 g/s (I could be wrong).

You best option is to run SD, unless you have to pass the emissions testing OBD2 no-DTC policy.

0411 LS1B PCM is going to be your best bet; if you want a higher MAF limit then you'd need to figure out how to have a late E67 function properly. Which brings it's whole set of issues... If you're really concerned about the 512g/s limit, I'd look at a standalone but you'll potentially lose some creature comforts plus it will require more work to integrate with the vehicle.

Thanks for the help, is there a good SD tutorial like the VE one?

Auto VE found it thanks!!