MAF calibration => help needed.

Hello

Recently, I installed an AFE cold air intake.
Truck runs still great, but I discovered that the fuel economy gauge in the dashboard alternate more than before.
Watching the numbers with the VCM scanner told me that the LTFT en STFT are on average 10% positive (sometimes even 40% in total)
So I guess, with the larger diameter of the air intake, the ecm miscalculate the air mass....

I decided to recalibrate the MAF table...
I don't have much experience wit HP Tuners , but I went this way:

Disabled the dynamic (high rpm to 0)
Disabled DFCO (Disable ECT hyst to 256?C)
Disable COT
Disable LTFT (Min ECT to 256?C)

I made a table to log the MAF frequency against the STFT
Problem is, when I start logging, the MAF frequency stays in the 0hz cel.... (Because i get no value for the MAF frequency)

Is there someone who knows what I'm overlooking?

I added the log file

grtz, D

Larger MAF tube requires MAF adjustment due to the lower hz reading

I don't have my laptop on me, so I can't look at your log, but do you have the correct maf frequency channel added? Have that being referenced by your histogram? Histogram column axis setup to reflect the maf table in the tune?

I picked the one under generic sensors - engine - airflow.

Meanwhile, tried the ones under specific parameters too, but these also won't work....

Yes, you don't have the MAF frequency in your channel list. You only have Mass Airflow lbs./min. in the channel list.

@ DGS: Thanks man!! Tried a lot off stuff, but it didn't came to me that it was possible to add a channel :p

Problem Solved!!

Glad you got it working. I log all channels and then when I create a new chart or graph, the data is there. If you have logged all channels , you can even replay an old log with new charts or graphs and get the data you need. Depending on what you are doing, you may not have to test drive again to create another log.

Maybe I am reading wrong, but I would think you would measure LTFT error instead of STFT wouldn't you? Assuming part throttle maf? Start car, reset ltft, idle 2mins, drive 2000tpm hold 5 secs up to 4000rpm holding 5 secs in 500rpm increments and use Average on the histo?

@ Poppacapp : I take the average of the STFT, with the LTFT disabled, because I guess this is more accurate. I hope I'm right to assume if it adds 10% more fuel, it means that there goes 10% more air in it.. The cells that are still empty, I fill in with an average of the previous cells so I don't have big changes in the values..
Now it's only testing.....

I've analysed the log, and I see that there are still a lot of fluctuations in the fuel trims...
Is this normal, or is there something else that needs to be disabled....

The one thing I don't see in the thread is: did you reset your LTFT's to 0 them out? If your LTFT's are not reset to 0 they will skew the STFT data you are seeing. Hard to tell where you are at because the only file posted is from before you added MAF frequency and set up your histogram that shows MAF error vs STFT.

I disabled the LTFT....
Do not know how to reset them....

I am reading on this forum for days now..... Everybody seems to have their one way to work, and I have the feeling I all mix them up...

not easy....

Quote:

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Originally Posted by Dmax1207

I disabled the LTFT....
Do not know how to reset them....

I am reading on this forum for days now..... Everybody seems to have their one way to work, and I have the feeling I all mix them up...

not easy....

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start with the GenIII forum, then read the Gen IV forum, then read the Gen V forum.

Yes, you are correct it isn't easy. What Higgs says is right (he is one of the most knowledgeable contributors on the forum), it is helpful to look at earlier generations to understand basic logic of how the GM ecu's are programmed. However as a note of caution, Gen V has some significant differences from earlier versions, more capable and more complex.

Now back to your problem. To reset fuel your LTFT's you must have your HPTuners interface connected to the car. Using the Scanner program, go to the "Vehicle Controls & Special Functions" button on the toolbar and you should see a command to reset fuel trims. The other stuff you have disabled is correct to tune using STFT's. There is more than one way to adjust your MAF but the method you are using will get the job done. Regarding your question about fluctuations, there will always be some fluctuation in STFT's. I'm not sure how much fluctuation you are seeing but you should expect to see STFT's to fluctuate some as there are many variables that will cause changes that STFT's compensate for as they keep the engine at the commanded air fuel ratio. If you post an .hpl file with MAF frequency enabled we can take a look at what you currently have going on and possibly help more.

Suggest looking at You Tube video titled LS3 MAF TUNING USING STFT - HP TUNERS by hughesperformancetuning. This is for a LS3 (Gen IV) but is still very much relevant for what you are trying to do. There are also some other excellent You Tube videos by The Tuning School and others that will help understand using HPTuners and tuning your truck These videos combined with the information in the HPTuners forum will help you through the learning curve which in turn makes tuning less frustrating and more fun.

Attachment 85428

this is a log file with the maf enabled....

Based on the log you posted. here is the key data needed to adjust your MAF. Left column is the MAF frequency and the right column is the % error the ECU is adjusting for to bring your air fuel ratio to commanded. My HPTuners is set up for an LT4 so your tune and HPTuners may have slightly different displayed frequencies. Positive numbers mean the truck is lean and the ECU is adjusting to richen it up (your truck is generally in this category). Negative numbers mean the opposite it is inherently rich and the ECU is adjusting to make the engine leaner to achieve commanded AFR. Keep in mind that are not changing airflow, you are changing the amount of air the engine thinks it is getting at a particular frequency. For example, at 2100 Hz your truck would like to think it is getting 7.7% more air and with that it will run at commanded AFR (and, at least in theory, requiring no LTFT or STFT adjustment). I usually target having fuel trims slightly (1-3%) negative. Do not worry about anything below 1800 Hz as the truck never runs there (after start up) and everything above about 7800 Hz appears to be open loop. Open loop tuning requires a wide band. It looks to me, based on this one drive, like your truck requires little or no adjustment at the higher frequencies and is probably OK as is when open loop.

MAF MAF %
Frequency (Hz) Error (g/s)
1800 4.5
1950 3.8
2100 7.7
2250 11.2
2400 8.9
2550 5.6
2700 4.0
2850 4.3
3000 4.1
3150 4.3
3300 5.1
3450 7.1
3600 4.6
3750 5.1
3900 4.0
4050 4.2
4200 1.4
4350 3.1
4500 3.3
4650 3.0
4800 3.6
4950 2.2
5100 2.6
5250 2.1
5400 1.8
5550 2.1
5700 2.1
5850 2.5
6000 2.4
6150 1.7
6300 1.5
6450 2.6
6600 1.9
6750 2.4
6900 2.1
7050 1.3
7200 -0.2
7350 -0.1
7500 0.2
7650 0.1

Today I finally found some time to continue the logging (holidays etc...)

I'm still not happy that the min and max values are so far apart..... (+50 to -13)

So I add the channel DFCO, PE, Hot enrichment and closed loop.

I disabled the PE mode also, because this was still active...

I added the log file of today, for hose who are interested..
I deleted the LTFT before start logging (thanks ELG :o:o)

I't is very strange, that the fuel system #1 status seems to go OL, even at low rpm, with low torque asked (STFT 25%)
I guess I still have a lot to do to get the MAF calibration fine....

By the settings, the DFCO should be disabled if ECT is below 256?C, but somehow it stil gets active...
So I added some extra changes, like only enable above 7000rpm, en disable if below 8000rpm
I'll test it tomorrow, but I guess it will do the trick....

Still need to figure out how to keep it in closed loop....
I guess that will give the most correct values...

Post a tune. Post a log.

Also, where did you get the row and column ranges for your chart? It should be copied from your Tune \Edit\VVE or VE table from the Editor, but can't view w/o a tune.