MAF Tuning

[phuz]

I have followed all the steps to disable STFT/LTFT, DFCO, and VE so that I could tune the MAF.
I went out and logged my wideband vs. MAF frequency and then applied that to the table (Multiply by half %) but I noticed it didn't change my idle AFR at all, even though it subtracted a substantial amount. So I thought I would just play with the idle section only to see what was going on. Normally at idle, it would be around 8g/s (~3300 Hz). I tried lowering it more and more but the AFRs didn't change. I took it to 2g/s and it still idled fine and still was rich (12-12.5). Just to make sure I wasn't missing something, I zeroed it all out and the car would die immediately upon starting.

Couple questions:

• Why is the AFR not changing whether I have 2g/s or 8g/s set for that particular MAF frequency? Is there a minimum fueling setpoint?
• When MAF tuning, should I be targetting 14.7 across the entire range, and then add back VE to compensate for the "load" regions? (I plan to do VE after MAF is done, and then enable both for the blend)

Here's the current tune:
2001 Corvette_with_Procharger_MAF_tuning.hpt

[phuz]

I did several trips up/down the highway with adjusting the MAF table (multiply by half %) each time.
It definitely helped get it really close under slow acceleration and while cruising, but it ended up making it go very lean under moderate throttle, so we're far from done.

Current tune and log attached.
2001 Corvette_with_Procharger_MAF_tuning.hpt
05-apr-2023-maftuning-2.hpl

[04silverado6.0]

I would recommend getting a map sensor that matches your setup. Also it would be a lot easier to use one of the SD custom os. You may be fine using the maf but you are loosing a lot of control and tuneability.

[phuz]

I would recommend getting a map sensor that matches your setup. Also it would be a lot easier to use one of the SD custom os. You may be fine using the maf but you are loosing a lot of control and tuneability.

I have the 2-bar MAP; just haven't installed it yet. I wanted to get the MAF dialed in first because I would like to use the MAF for low end and kick over to SD when I get into load.

[Josue Galban]

I have the 2-bar MAP; just haven't installed it yet. I wanted to get the MAF dialed in first because I would like to use the MAF for low end and kick over to SD when I get into load.

To begin with, remember that the flow of the maf, the higher the number of G/s, the more oxygen, therefore, the less fuel. So, try raising the number by, say, 5% upwards, you put 1.05 and the multiplier for downwards is 0. 95 try uploading it grab the entire table if it obeys it's fine check your pe and check the oxygen sensors well they may not be well disabled

[phuz]

To begin with, remember that the flow of the maf, the higher the number of G/s, the more oxygen, therefore, the less fuel. So, try raising the number by, say, 5% upwards, you put 1.05 and the multiplier for downwards is 0. 95 try uploading it grab the entire table if it obeys it's fine check your pe and check the oxygen sensors well they may not be well disabled

Yea, the higher the Hz, the higher the flow rate. So by increasing the g/s in a cell, you are telling the PCM that it's flowing more air, and you will get the PCM to add more fuel, and vice versa for lowering the g/s.
I have the O2 sensors (narrowband) disabled, and I am doing this based on my wideband signal via Prolink cable.

[Josue Galban]

Yea, the higher the Hz, the higher the flow rate. So by increasing the g/s in a cell, you are telling the PCM that it's flowing more air, and you will get the PCM to add more fuel, and vice versa for lowering the g/s.
I have the O2 sensors (narrowband) disabled, and I am doing this based on my wideband signal via Prolink cable.

uhmm and why didn't you try moving little by little

[phuz]

uhmm and why didn't you try moving little by little

I did. I did a multiply by half % each time. Just want to make sure I'm going about this the right way. I want to yank out some more timing before I get into the higher flow rates (where it's currently going lean).
I think my primary concern right now is why it's staying rich at idle even though I'm dropping the g/s each time. It's like it's adding fuel from something else and not solely fueling based on the MAF.

[Josue Galban]

I did. I did a multiply by half % each time. Just want to make sure I'm going about this the right way. I want to yank out some more timing before I get into the higher flow rates (where it's currently going lean).
I think my primary concern right now is why it's staying rich at idle even though I'm dropping the g/s each time. It's like it's adding fuel from something else and not solely fueling based on the MAF.

How is your PE and the MAF sensor? Worry about adjusting the idle correctly. That is your main job. Get on top of that, how do you have your injectors? in the range

[phuz]

How is your PE and the MAF sensor? Worry about adjusting the idle correctly. That is your main job. Get on top of that, how do you have your injectors? in the range

Not sure what you mean about how is the PE and MAF? The PE is only using EQ Ratio based on RPM. The tune is attached in the top post if you want to look at it. The injector flow is set up correctly per the manufacturer.

[Josue Galban]

Not sure what you mean about how is the PE and MAF? The PE is only using EQ Ratio based on RPM. The tune is attached in the top post if you want to look at it. The injector flow is set up correctly per the manufacturer.

I did not explain it well but what does it matter move it little by little and if you do not notice changes try to work with the MAP in main VE the MAF sensor should work, it should obey anyway you can go to engine diag and check the airflow if you have disabled the MAF

[phuz]

I did not explain it well but what does it matter move it little by little and if you do not notice changes try to work with the MAP in main VE the MAF sensor should work, it should obey anyway you can go to engine diag and check the airflow if you have disabled the MAF

I have VE completely disabled right now, along with all fuel trims, so that I can tune the MAF by itself first.
To do this, you go to Engine -> Airflow -> Dynamic -> High RPM Disable set to a number lower than your idle RPM. This will force it to use MAF only.

[phuz]

Clearly I'm missing something here, because I've done about 80 miles of up/down the highway making small tweaks each time, but take a look at this log from yesterday. Specifically, the 3:58 mark and the 5:44 mark.
The MAF frequency is virtually the same in these two sections of the log, but the AFR is substantially different. How? The only difference was the first mark was 5th gear (higher rpm, lower MAP) and the second was 6th gear (lower RPM, higher MAP).
Flow is flow, so the AFR ideally should've been the same.

I have the tune forced into MAF-only, with trims and PE disabled and the open-loop EQ is set to 1.00 above 194F.
Attached is the log and the current tune that was used for yesterday's drive. Please point out what I'm missing as I'm going to halt my MAF tuning until I figure out what else is still in play.

07-apr-2023-maftuning-3.hpl
2001 Corvette_with_Procharger_MAF_tuning.hpt

[dhoagland]

I've been out of this for awhile....
But I believe the "MAF only" mode still somewhat references the VE table. If it was me I would fail the MAF, Tune the VE, then start over.

If you look at your RPM and MAP and then look VE table at your given time clips in the log they are considerably different values
Just a thought

For your idle AFR are you looking at you base idle air flow?
And from memory if its idling stable you won't mess with that until VE and MAF are dialed

[phuz]

I guess I'll do that. I'm used to tuning VE from my Haltech anyway.
This is the first I've heard of it still using the VE table in MAF-only mode. If that's the case, then that would explain this to some extent.

As for idle AFR, wouldn't the MAF be targeting the open-loop EQ ratio defined for that MAP/ECT cell? In other words, if I have an EQ ratio of 1.00 for that cell, it should be fueling based on my stoich value of 14.68. Unfortunately, I cannot find any parameter to datalog for commanded EQ ratio or anything like that. I guess my PCM doesn't support it?

[dhoagland]

Again I've been out for awhile so I could be remembering wrong. I'll post a few idle Tuning threads and maybe that might help answer your question.... One thing I do remember is you need your VE/MAF Injector data dialed before fine tuning idle (which I know you are trying to do)

The second one is a very long thread, but Tons of info for GEN3 idle tuning

https://forum.hptuners.com/showthrea...fig-help/page2
https://forum.hptuners.com/showthrea...e-(w-pictures)

[phuz]

Again I've been out for awhile so I could be remembering wrong. I'll post a few idle Tuning threads and maybe that might help answer your question.... One thing I do remember is you need your VE/MAF Injector data dialed before fine tuning idle (which I know you are trying to do)

The second one is a very long thread, but Tons of info for GEN3 idle tuning

https://forum.hptuners.com/showthrea...fig-help/page2
https://forum.hptuners.com/showthrea...e-(w-pictures)

Much thanks!

The only injector data I'm aware of is under Fuel -> General. I have all those values specified per the data sheet provided with my Siemens Deka 60# injectors.