Nuisance P0068 while MAF tuning?

[L96_1500]

After getting a stable drivable tune for my LC9 to L96 swap, I am working on getting the MAF curve dialed in. The stable tune v19 is extremely lean. After logging data from that tune using Cringer's maths for MAF and VVE, then multiplying by percent into the new tune, I got a P0068 and REP during the next logging session. Thinking I made too drastic of a change, I made tune v22 with multiplying by percent half instead. During today's logging session it went into REP again with P0068. Am I getting a false positive P0068 and should raise the enable RPM until I get the MAF curve dialed in, or is there something off in the tune that is leading to it? FWIW I have a few hundred miles of driving on v19 with no P0068 or REP issues, but I am getting a P0106 from it.

[verlon]

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[SiriusC1024]

I have a layout for Cringer's DynAir method. It shows you're 30-50% lean on VVE. The discrepancy between MAF and VVE is triggering P0068.

[Alvin]

After getting a stable drivable tune for my LC9 to L96 swap, I am working on getting the MAF curve dialed in. The stable tune v19 is extremely lean. After logging data from that tune using Cringer's maths for MAF and VVE, then multiplying by percent into the new tune, I got a P0068 and REP during the next logging session. Thinking I made too drastic of a change, I made tune v22 with multiplying by percent half instead. During today's logging session it went into REP again with P0068. Am I getting a false positive P0068 and should raise the enable RPM until I get the MAF curve dialed in, or is there something off in the tune that is leading to it? FWIW I have a few hundred miles of driving on v19 with no P0068 or REP issues, but I am getting a P0106 from it.

This basically means your VVE isn't matching up with your MAF. The right thing to do would be to fail the MAF, dial in VVE, then turn MAF back on and finish up. 0068 can be disabled while you are doing this.

[JayRolla]

I would just go back to the old school way. Disable MAF and tune VVE with your fuel trims. What I do is if the car is showing say 10% lean via fuel trims I add 10% to the entire VVE table. I keep adding, removing via half till its as close to 0 as possible. Then I go and dial in the VVE using the fuel trim numbers. Now enable the maf and disable dynamic airflow and dial in the maf via AFR error.

[L96_1500]

Now that I know I can raise the P0068 enable RPM, I'll continue what I was doing, as I was making progress with the MAF errors using the DynAir method.

[Alvin]

I'm not fond of that method. Failing the MAF guarantees success.

[GHuggins]

The Dyn method gets it spot on. I've actually checked it a few times. If you think about it in it's simplistic form if everything is right VE airflow and MAF airflow will and should be really close to one another. Before the dyn method I was using MAF g/s to VE g/s error to quickly dial in the VE. The dyn method just takes that a step further using what the ECM uses for it's calcs to determine fueling.

Plus there's the fact that they both affect each other as there is a percentage of VE used at all times by the MAF. It will seem like you're going in a circle for a revision or two, but they usually come right in line.