Auto MAF (the begginning)

[kwhiteside]

To add to it, I scanned my log and found that at idle, my Wideband AFR is almost always about .5 to .75 higher then the commanded 14.63.

Oh, before I started this, I pulled my LC1 out of the header and calibrated air calibrated it. During AutoVE we got it just about matching commanded too.

What do you guys think.
Could it be -
MAF really off, just keep tweaking it?
Leak?
Mods of bigger TB, Intake, Headers?

[WeathermanShawn]

When you complete 'AutoMAF' are you going back to closed-loop (using O2 sensors to maintain stoich), or open-loop?

Closed-Loop gets someone of a bad rap, but if you are getting close to where you want to be on your tune, enabling Trims will help 'clean-up' some of those problem areas.

On the DFCO debate, as always Mick has a great point about the 'Rich Decel' that can happen when you take your foot off the the throttle. I think however, for now you can work your current tune, but just be aware of the that the 'off-throttle' areas can be a challenge to tune.

[kwhiteside]

I want to puke. I just plugged in the stock z06 figures into the spreadsheet and found that my original tunes Injector Flow Rate table B4001 was not right.

My Injectors -
2001-2003 LS1/LS 24.7 (3 bar) 28.5 (4 bar)
part number 12561462
lbs-hr.@3 bar = (43.51 psi)
lbs-hr.@4 bar = (58.02 psi)

This means I have to start all over? Even redo my AutoVE work?

Pic below shows the difference.

[mr.prick]

If your injectors are stock, leave all the injector tables stock.
A Wahlbro 255lph will give you 60psi at idle but at WOT you will drop to 58psi,
if your battery voltage does not drop too much at WOT.
A tensioner helps to keep belt slippage down.

[kwhiteside]

I drove to work with my original b4001 table, drove home with the new one and reverted back to my first AutoMAF. The morning log had my AFR way off commanded, especially near idle. The log from the way home took that pukey feeling away as my AFR was surprisingly close to commanded. I'm going to apply tweaks to my B5001 MAF table from here. I'll know more tomorrow as I'll get two more log sessions in. I never thought I would enjoy my 45 minute commutes. Now I can't wait for those logging sessions. I suppose I'll have to go thru the VE again to get it right. That part has me perplexed because my AFR was following commanded real well by the end of my logging. I imagine I'm going to be running real rich when I go back to AutoVE mode with this new IFR b4001 table.

[5.7ute]

I drove to work with my original b4001 table, drove home with the new one and reverted back to my first AutoMAF. The morning log had my AFR way off commanded, especially near idle. The log from the way home took that pukey feeling away as my AFR was surprisingly close to commanded. I'm going to apply tweaks to my B5001 MAF table from here. I'll know more tomorrow as I'll get two more log sessions in. I never thought I would enjoy my 45 minute commutes. Now I can't wait for those logging sessions. I suppose I'll have to go thru the VE again to get it right. That part has me perplexed because my AFR was following commanded real well by the end of my logging. I imagine I'm going to be running real rich when I go back to AutoVE mode with this new IFR b4001 table.

If you scale the VE table by the same amount that you changed the IFR table everything will come back into line. For example, if you raised the IFR by 10% you need to raise the VE table by 10%.
Check out Marcins (Redhardsupras) blog for the indepth math on how this all works. He can explain it much better than I ever could.

[joecar]

+1 on what 5.7 said.

I calculated your spreadsheet IFR to be different by an average of -2.2% compare to your original IFR (please do check my math).

[kwhiteside]

I've already tweaked the table. I couldn't figure out how to get the % to do it right in the Scan tool, so I copied into excel and multiplied by .9777

Original kPa 0 value 3.6719 X .9777 = new value of 3.5910. Worked same for the other kPa's too.

Basically dropped all my my VE values just a tad, making everything a tad leaner. The lower IFR values in B4001 will cause the PCM to shoot a little more gas to achieve stoich.

I've got a couple more days of AutoMAF before I switch back to the AutoVE to validate that side of things.

Question for you guys. Before I started all this tuning, I took the car to a tuner for a tune. He basically said -

Ken, things are pretty far off on your car. I can't get AFR to follow commanded. I know you have EFILIVe and the wideband so it would be best if you tune it. Just to help you out Ken, I did back off the timing a bit so you don't fry anything at the track. So, my question is about that timing he backed out. How do I tune the timing back to optimial but safe? Please point me in the right direction.

[mr.prick]

In the Adjust: box type the value you want to add, negative numbers will subtract.
Adding a negative number is the same as subtracting.
To decrease you need - in front of the number

[joecar]

You could try the stock Z06 timing tables, this would be safe now because you know your AFR's are sufficiently rich... but keep an eye on KR and ECT, and make sure the AFR never goes lean when you're abusing your engine.

Your tuner was telling you that if he had to do it it would take a lot of time (multiply by hourly $ rate) and that you would be able to spend more cost-effective-time on it than he could... he is honest (he didn't just hack a tune into it and charge you $500).

Once you have the VE and MAF BEN's all sorted out, you could invest on a dyno session with your tuner to setup ignition timing and to fine tune the commanded AFR for best torque and power.