What to Tune First

[TAQuickness]

This is not the end-all-be-all bible to tuning. It's just 1 of 101 ways to tune that delivers consistant and repeatable results. As of late, I have read a few tuning books that reinforce this methodology.

1. IFR Table {B4001}: Very important that you start here and get this table right. You should use the IFR spreadsheet RedHardSupra made available on his website (or a similar one). This is the one known constant that you will base the rest of your tune on.
2. VE Table {B0101}: You will use the AutoVE tutorial to get this table dialed in. This will establish the base air mass model for your engine.
3. *Optional* MAF Table {B5001}: The same concepts you learn tuning the VE table with the AutoVE tutorial are to be applied to the MAF table.
4. Idle & Idle Transistion tables. Ironically, idle is the first thing your engine does and one of the last things to get tuned. An engine that won't idle is a frustrating driving experience - BUT, you must complete the previous steps to derive an accurate air and fuel mass flow model in order to achieve desirable idle quality. SSpdDmon has posted some great idle tuning information here
5. Spark Tables: You will need a load bearing dyno to accurately dial in your spark. Basically you just advace until you make no more torque/power then back off 2* for safety.
6. WOT: Best to do at the same time as your spark tuning to save on dyno $. In this case you will be adjusting spark & fuel to achieve maximum torque and horsepower.

[jfpilla]

This is not the end-all-be-all bible to tuning. It's just 1 of 101 ways to tune that delivers consistant and repeatable results. As of late, I have read a few tuning books that reinforce this methodology.

I think there is one best way. It's at times elusive, but with what you describe it probably ends up being easier than chasing ones tail from a patched tune.

There are always questions posted about where to start first.

This should be a sticky!

[VTC_WS6]

Excellent info, had I had my IFR's down correctly I wouldn't have spent the last 2 days chasing my own tail.

[SSpdDmon]

Something I've been trying lately...

Another theory to chew on that I have tried and posted before...

1. RPM Threshold for Airflow Calc {B0120}: Using your stock, screened MAF, set this threshold to 100rpm to enable a full, MAF-only tune. The purpose of this is to reverse engineer your IFR table based on how the injectors flow in YOUR car.
2. IFR Table {B4001}: Based on what you believe to be true about your injectors, you should use the IFR spreadsheet RedHardSupra made available on his website (or a similar one) to initially set this table. Then using the reciprical of your BEN factor for your WBO2 along with the MANVAC pid, you'll correct this table. Remember, raising values lean out AFRs and reducing values richen AFRs in this table. This will become an important constant that you will base the rest of your tune on.
3. VE Table {B0101}: After returning the B0120 to stock and setting your tune per the the AutoVE tutorial, you can begin to get this table dialed in. This will establish the base air mass model for your engine.
4. *Optional* MAF Table {B5001}: The same concepts you learn tuning the VE table with the AutoVE tutorail are to be applied to the MAF table. Although using this method, there shouldn't be much adjustment needed for this table due to steps 1 and 2.
5. Idle & Idle Transistion tables. Ironically, idle is the first thing your engine does and one of the last things to get tuned. An engine that won't idle is a frustrating driving experience - BUT, you must complete the previous steps to derive an accurate air and fuel mass flow model in order to achieve desirable idle quality. SSpdDmon has posted some great idle tuning information here.
6. Spark Tables: You will need a load bearing dyno to accurately dial in your spark. Basically you just advace until you make no more torque/power then back off 1~2* for safety. Remember, things like compression ratios and altitude can effect the amount of timing your engine will run best at.
7. WOT: Best to do at the same time as your spark tuning to save on dyno $. In this case you will be adjusting spark & fuel to achieve maximum torque and horsepower.

Sorry, I stole your format TAQ 'cuz I'm lazy these days.

[jfpilla]

SD,
Step 1 looked very interesting, so I tried it today. I'm happy to say my MAF table was right on. Commanded and Actual AFR tracked very well and Ltrims were good. It seems step 1 is essentially a "super filter", eliminating transition impact from the VE's. My filters must be good. I like this idea and will play some more.
A couple of questions:
If you have programmed IFRs and have tuned the MAF why would you retune the IFRs since the MAF has now compensated?
Also, if the MAF is now correct why redo it with B0120 at 4000 rpms, since you can't turn off the VE's and have eliminated transitions it would seem everything is already correct?
Thanks
Joe

[SSpdDmon]

SD,
Step 1 looked very interesting, so I tried it today. I'm happy to say my MAF table was right on. Commanded and Actual AFR tracked very well and Ltrims were good. It seems step 1 is essentially a "super filter", eliminating transition impact from the VE's. My filters must be good. I like this idea and will play some more.
A couple of questions:
If you have programmed IFRs and have tuned the MAF why would you retune the IFRs since the MAF has now compensated?
Also, if the MAF is now correct why redo it with B0120 at 4000 rpms, since you can't turn off the VE's and have eliminated transitions it would seem everything is already correct?
Thanks
Joe

This is starting with an untuned car. The idea is you keep the stock MAF curve and build the IFR and VE tables off of it instead of using what the IFR should be (which it may not really be in reality) and building the VE/MAF. I ran my 23x/23x H/C Camaro this way...threw a stock tune in and turned the VE off. It ran pretty good right off the bat, which makes sense because the MAF was doing a pretty good job of reading the incoming airflow based on the stock curve.

The reason why I suggest this is because the stock MAF has a great deal of R&D into it on flowbenches to determine the airflow values. When you change the VE with a head/cam swap or change out the injectors, why should the MAF change so much? You didn't drastically alter the way the MAF functions. Then again, assuming you don't change the injectors, this theory is questionable.

I guess either way you choose to tune, I believe there is an unavoidable fudge factor. It's just where you choose to fudge that determines the style of tuning you do.

[odd boy]

Guys,

I've some questions:

1. Assume that I didn't upgrade the stock injectors, do I need to tune IFR Table {B4001}.

2. why don't we keep the MAF on all the time and keep VE off?

[SSpdDmon]

Guys,

I've some questions:

1. Assume that I didn't upgrade the stock injectors, do I need to tune IFR Table {B4001}.

Yes or no depending on how you choose to tune. Trying it my way (leaving MAF curve stock), you would end up tweaking the IFR before touching the VE. Using the orginal method, no - you wouldn't touch the 17 IFR cells. You would tweak the 85+ MAF cells though.

2. why don't we keep the MAF on all the time and keep VE off?

The theory is that the MAF sensor is optimal for steady airflow. During transitions, a VE or blended MAF/VE table is better. At least, that's the theory.

[joecar]

My understanding of when is MAF or VE used:
- Below B0120: combination of MAF table (steady state) and/or VE table (transitions).
- Above B0120: MAF table.

EDIT: corrected my post.

[jfpilla]

My understanding of when is MAF or VE used:
- Below B0120: combination of MAF table and/or VE table.
- Above B0120: MAF table.


So the VE still kicks in during throttle transitions, which means you'll have to filter these out completely.

- Throttle Transitions: VE table, regardless of B0120.

If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.

This is the EFI descriptionof B0120. Is it wrong?