Plus and minus of methods

[BlueDragon]

Ok, It looks like there are several schools of thought on bringing the LTFTs into line.

1. The one I see here most of the time which is the Disconnect the MAF and work on the VE table wideband and narrow band methods.

2. Michael Buie (a.k.a Black LS1 T/A) Which is to adjust the injector flow rate table and the MAF Table if you have a modified MAF. He does have the theoretical disclaimer that if you have not changed your injectors you should look for other problems. He also has the MAF Table and the PE RPM table approach.

3. And I think there is a third method which HP tuners has in their Volumertric Effeciency Table Tuning.

What are the positives and negatives of using each. I do not have the wideband setup yet. I did modify my MAF so correcting the MAF table seems like the first place I should go.

[jimmyblue]

My guiding principle is "like for like". That means,
you leave the injector table be unless you changed
the fuel injectors or fuel system pressure profile;
you leave the MAF alone unless you messed with
the MAF, and so on. Don't compensate a problem
with something unrelated, even if it might be
effective; lies tend to accumulate but the truth is
pristine.

[BlueDragon]

;D I like your thinking That is exactly where I was comming from with the question. My C5 is an every day driver. I don't need to go to the knats _ _ S of performance. MAF must stay, it must pass Calif Emissions, and be reliable and get good milage on long trips. It does have some mods and will be getting a few more.

Good Answer!

[MNR-0]

I used to use the IFR approach but since using the MAF to align commanded AFR with wideband AFR I won't go back to IFRs again.

I command a set AFR in the PE table and modify the MAF table until I reach said commanded AFR. For LTFT trimming, I just go off the LTFT cells as I run closed loop, whether in SD or MAF. Ive even changed my O2 sensor switchpoints to dial in my closed loop AFRs to match 14.63.

The idea is to get your commanded AFR and actual AFR the same. How you get there is up to you.

Personally, if I had the time to spend with a wideband, I would do it in this order:

1. align closed loop O2 sensors to stoich
2. disconnect MAF and trim the part throttle VE table via the O2 sensors
3. trim the WOT VE cells to a commanded linear PE
4. reconnect MAF and trim the part throttle MAF
5. trim the WOT MAF curve to a commanded linear PE

Everything should then be in sync. Now you can play with WOT power tuning knowing your commanded PE AFR will be actual AFR.

[S2H]

personally..
I like to go this route

disable MAF and tune VE using Wideband o2 and AFR error %(also helps to set closed loop ect to 284 and change closed loop eq ratio to 1.00)
when done with VE re-enable MAF and tune it with wideband using same method using wideband and AFR error %
Tune PE also with AFR error %...usually you can do it at the same time as PE when you log commanded afr and actual afr also be sure to set up your pe to be EXACTLY what you want it to be...for me PE is usually 12.96(or an eq ratio of 1.131

re- enable closed loop and set o2 switching to be correct for stoich for your setup

If you have an Auto...you also need to recalculate your shift tables because of the recalculated MAF...or you can leave the MAF table Stock and use the IFR to adjust(which I think is a bad band-aid solution...or just leave the MAF table stock and put the car in full time SD(which I prefer)

atleast thats teh quick and dirty explination of what I do