Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

So first we look at the Engine Coolant Temp ok it's 57* F, so here are our thoughts:

• the Channel is working / the Sensor is working
  
• later we will know what should be happening at this temp, for now this is an unkown to us, but that's ok we are learning one bit at a time

looking below this Channel, at the next one Fuel System #1 Status says OL - Not Ready, our thoughts:

• We got some sort of result in here, so at least the channel is working, that's good
  
• OL must stand for Open Loop, ok we guess it's not in Closed Loop yet, we'll see what happens to this value later as the vehicle warms up and the temperature increases

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

looking at our next Channel, Barometric Pressure, our thought are

• we have a value so we picked the right PID (Parameter ID) and the sensor is working
  
• comparing the value to our iPhone Weather app, they match so it's working properly

for now, the channel below Manifold Vacuum we just want to make sure it has a value, and it is as close to zero as possible

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

now you may notice that the Barometric Pressure Channel reports in PSI instead of inHg (Inches of Mercury) hey that's Physics for you (seven different ways to say the same thing), and yes this is one of the things that you will do battle with in HP Tuners quite often, making sure you are comparing Apples to Apples and not Apples to Oranges type of thing, so simply right click that Channel select Units and choose the format you desire

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

the Intake Air Temp channel is next, and this one can get skewed like in my case cause my truck has been parked in the shade all day so it shows a temp a few degrees below my iPhone Weather app

So you knowing this, maybe use a local indoor outdoor thermometer barometer temp gauge thingie to get a better reading of the local air temp, or park your truck in a different spot, you get the idea

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

Mass Airflow Sensor shows a perfect ready to go Key On engine not running reading of 0 hertz

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

for the Engine RPM we just expect to see a value of 0 to prove the tach signal is coming through

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

same goes for the Timing Advance channel we don't expect to see anything above 0 with just the key on and the engine not running, but seeing a zero is a good sign means we picked the right PID (Parameter ID) and there is a signal on the line

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

and both O2 Voltage sensors are perfectly in the middle of .100 and .900 volts with the key on, and the vehicle not running

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Key On - Vehicle Not Running - Systems Check

now I would be lying if I told you I wasn't genuinely concerned about the low Control Module Voltage even if this is key on engine not running, something may be draining my battery here and low battery voltage can brick your PCM when you are flashing it

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

OK, let's use our Basic Channel config to evaluate the second of the three vehicle conditions:

1. Key on - vehicle not running

2. Vehicle Running - Open Loop

3. Vehicle Running - Closed Loop

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running Open Loop - Systems Check

So now that the truck is running we see the presence of Manifold Vacuum, we observe that our value is now well above 0

We see a similar result for the Mass Airflow Sensor

Obviously Engine RPM has climbed as well, though we don't know if it's where it should be yet, but that's ok for now, we are learning

likewise we have a Timing Advance that is greater than zero

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running Open Loop - Systems Check

now we see an interesting condition regarding our two O2 Sensors Voltage, it appears it went from middle of the road around .450 with the key on to above .900 with the truck running and warming up, later we will learn that this reflects a rich condition, but since the rig is warming up this is acceptable (think choke on)

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running Open Loop - Systems Check

and finally the Control Module Voltage looks much better, with the engine running, it is above 14 volts

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Lastly, let's use our Basic Channel config to point out the channel value differences in the final of the three vehicle conditions:

1. Key on - vehicle not running

2. Vehicle Running - Open Loop

3. Vehicle Running - Closed Loop

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running - Closed Loop

I hope you stuck it out this far, as things began to get interesting. I pointed out earlier the importance of the Engine Coolant Temp and here is the first example of its cause and effect.

When the temperature reaches 131*F notice what happens in the Fuel System #1 Status channel below it?

The status changes from OL - Not Ready to CL - Normal CL meaning Closed Loop now.

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running - Closed Loop

lets take a deeper dive and see what exactly caused that switch from Open Loop to Closed Loop

We know all of our configuration settings come from the VCM Editor so we fire it up and go to Engine \ Fuel \ Oxygen Sensors and look under the Closed Loop Enable heading where we find the ECT vs. IAT table (highlighted in pink for easier spotability that's all)

We put our mouse over it, and glance at the bottom of the screen where we find the Context Clues, which read: This table sets the coolant temperature required to enable Closed Loop in relation to inlet air temperature (IAT).

We open up that little guy, and it's not really a table as it is a list, but so be it. We quickly and easily see that once the ECT (Engine Coolant Temp) hits 131 (the big green bar) and our Intake Air Temp is above at least 50* we will turn on Closed Loop. Cool beans, so things are working as they should and now we know why.

Don't take this for granted, someday you may be troubleshooting an issue caused by your PCM never entering Closed Loop mode, so just keep that in mind please.

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running - Closed Loop

further down the list allow me to point out another cause and effect of you guessed it the Engine Coolant Temp

The engine is a little warmer now, it has reached 154* F, it's time to cause another thing to happen...

Note the drop in Engine RPM to approximately 550

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

Vehicle Running - Closed Loop

once again lets take a deeper dive and see what exactly caused the RPM to settle in at 550

so back to the VCM Editor we go (you will find this is the common Tango you will be performing whilst dueling HP Tuners ie. going to and fro from VCM Scanner to VCM Editor and back)

Engine \ Idle \ RPM is where we find the Base Setpoint heading and the Base table lurks under it

with our mouse hovering over it, we glance below to see: This table controls the desired idle RPM vs. Engine Coolant Temperature.

This being an actual table and not a simple list, allow me to explain how I read it.

There are four conditions:

• In Gear AC off (as in stopped at a stop sign or a red light)
• In Gear AC on (as in stopped at a stop sign or a red light)
• P/N AC off (in Park or in Neutral AC off)
• P/N AC on (in Park or in Neutral AC on)

So in our case in Park with the Air Conditioning off (deleted actually) and with the Engine Coolant Temp at 154* F we should be idling at 550, and we are. High fives all the way around!

Re: HP Tuners Tutorials - Chapter 1 - Logging
 

This concludes Chapter 1 - Logging

I hope I whetted your appetite for doing some tuning on your own or at least exploring the VCM Scanner.

If you have some channels you like to use to do your initial system checks that I have omitted please let us know, we're all here to learn.

Re: HP Tuners Tutorials
 

I have been following along the entire time and have learned a lot. Thanks again for doing this.
Jimmy

Re: HP Tuners Tutorials - Long Term Fuel Trims Short Term Fuel Trims
 

Long Term Fuel Trims and Short Term Fuel Trims, yeah we all heard the terms or the four letter acronyms LTFTs and STFTs, but what are they really?

A long time ago a teacher I had would tell us to substitute a word for a term we did not know instead of defining it for us, and it worked, so let's try this, any time you see the word Trims substitute it with the word "Changes"

So Long Term Fuel Trims become Long Term Fuel Changes and Short Term Fuel Trims become Short Term Fuel Changes

You could also use the word Adjustments or modifications, or what ever you come up with that works for you.

Now some may find the following analogy or example silly, but I think it works as we all can relate to it, plus everyone enjoys a good short story.

So it's the first day of Winter and you have to get dressed for school. So you put on the usual a T shirt and some jeans (socks, shoes and underwear is assumed) so in other words your VE outfit your Volumetric Efficiency or standard outfit.

On Monday you step outside and start walking to school, soon you find it's colder than you expected but you press on.

Tuesday same thing you throw on a different T shirt but still just a T shirt and a pair of jeans and you head out, freezing your butt off all the way there.

On Wednesday you step outside in your T shirt and a pair of jeans and you say screw this I am making an adjustment and you grab a jacket and put it on and zip it up to the top (there you just made a Long Term Fuel Trim) from here on out you will bring a jacket until the weather will get too hot again. You walk to school wearing that jacket but once you get to class you are sweating, you think nothing of it.

Thursday you head outside in a T shirt, jeans, and jacket of course, but half way there you think I'm getting hot, I should unzip my jacket (A Short Term Fuel Trim change) you get to school and you are no longer sweaty like the day before, you think I think I got this

Friday morning you put on your T shirt, jeans, and a jacket but you don't zip it up today, nope the Short Term Fuel Trim has now become part of the Long Term Fuel Trim baseline if you will

now if you start walking to school and it gets too cold, starts raining or snowing, by all means you have the freedom to zip up your jacket again, making yet another Short Term Fuel Trim adjustment/change

Re: HP Tuners Tutorials
 

Just wanted to clarify something that had me tripped up for a while and may help you. The objective is to get us thinking, in a non biased way as realists.

Do you need a Wideband Oxygen Sensor AFR Gauge to tune?

The short answer is no. The better answer is, it depends.

I bring this up for two reasons:

1. We need to understand what is controlling what as the vehicle goes through it's operational phases in order to determine for ourselves which tuning method to use and why.

2. There are many articles written on how to tune and especially many YouTube videos out there as well that do not clearly state in their title / subject which method they are using, and a beginner can spend a lot of time pulling their hair out trying to figure out why the methods differ.

Let me preface what I am about to say and tell you that I am not anti Wideband gauges I use them I run them in my vehicles, however there are Pros and Cons to using both methods.

Tuning Using the Stock Narrow Band Oxygen Sensors

PROS

• no additional costs, you already own these sensors
• in the end the PCM relies on and uses these sensors to operate, not the Wideband (think about that for a minute) this argument gets lost quite often in the debate

CONS

• can't tune Open Loop state with them such as WOT
• can't see actual ratio values in quantitative terms, ie 12.5 AFR or 15.9 AFR

You can tune 90% of your naturally aspirated engine using the narrow band method. The only thing you can't tune using the Narrow Band O2s is Wide Open Throttle aka WOT. Why did I say 90% because when it comes to street cars, our daily drivers think about it, how much time do you spend flooring it? Be honest with yourself, you probably rarely gun it with the pedal to the floor, right?

Think of the engine operation as an Oreo Cookie, the black parts being something called Open Loop and the white middle being Closed Loop. When you first start your car it is running in Open Loop, then once it warms up it enters Closed Loop (idle & cruise), then when you floor the gas pedal aka WOT you are once again in Open Loop (the other side of the cookie). In Open Loop the PCM is not relying on the stock narrow band O2 sensors, it is simply not listening to them. That is why you can not tune WOT with narrow band oxygen sensors.

Tuning Using Wideband Oxygen Sensor(s) AFR Gauge

PROS

• able to tune entire operation spectrum (idle, cruising, WOT, etc.)
• read actual ratio values in quantitative terms, ie 12.5 AFR or 15.9 AFR

CONS

• additional costs (parts and installation, bung welding, etc.)
• vehicle does not operate using Wideband sensors for input, calibration differences could impact final results
• often times Wideband is a temporary install and not permanent
• Wideband placement during tuning
• technically you are always tuning in Open Loop

It is no secret that the placement of the oxygen sensor can yeild different readings. Put it too close to the collector you get one value, put it too far past the collector you may get a different value, hewk just shove it in the tailpipe you can get yet a different reading. A lot of tuners will remove a narrow band sensor and screw in a wideband in it's place, the problem with that is, it is temporary and only tells you what you got while you are on the dyno during that hour session.

I used to play Water Polo, and our team was pretty darn good. Most of our time was spent in the pool playing [ahem] Water Polo. Folks would often times wonder what made our team so good or what was the secret that our coach had, and it was that we did not do drills, we did not lift weights, we did not run laps or stairs, we just played Water Polo. We played a lot of gosh darn Water Polo, ha ha.

I like to street tune my vehicles, because I drive them on the street and not on the dyno, ha ha. When I log my data I like to log it while driving to work or log it while driving back from work, more than taking the vehicle for a random test run down roads I will seldom or never take. In other words tune for the conditions you will face not well you get the idea...

Don't get me wrong there are good dyno tuners out there, but I hope I am getting the concept through. Getting your vehicle tuned for two hours on a sunny day on Saturday morning in a guys shop with a huge fan blowing on the front grill to keep it cool with a Wideband AFR gauge shoved into the tailpipe on a two foot long stick may not exactly precisely represent the driving conditions you face on a daily basis (cold mornings, scorching hot afternoons, rain/humidity), are there any hill climbs, how about descents, etc. How about bumper to bumper rush hour traffic?

... and please don't get me started on Mail Order PCM tunes!!! hee hee

RECOMMENDATION: In the end I like to use both methods, aka the belt and suspenders solution, that way you can cross check your results and perhaps account for any discrepencies.

Re: HP Tuners Tutorials
 

I just received my HP tuner equipment in the mail last night. I will go back review the thread & make wire harness to power up my ECM so I can work on it on the bench while it’s raining. Until I get my engine harness reworked and my truck is ready.

Re: HP Tuners Tutorials
 

Is this for "Snow White" yer '71 4x4 2004 5.3L?

Re: HP Tuners Tutorials
 

Yes it is

Re: HP Tuners Tutorials
 

Nice description of fuel trims! I wish I would have had someone put it in those terms before I started playing around with tuner pro and TBI.
Also a great way of summarizing the use of NB vs WB. I did my initial TBI tunes on the Caddy in open loop with the wideband, and now do my small tweaks off BLM (fuel trim) values, with the wideband just as a verification since it does respond faster. It is helpful for quicker throttle transitions, maybe the LS pcm reads/responds fast enough. TBI sure doesn’t.:lol:

Re: HP Tuners Tutorials
 

Thank you I appreciate that.

Nice, you are a braver man than I, ha ha.

Re: HP Tuners Tutorials - MAF Calibration
 

MAF Scaling - Calibration

Arguably the Mass Air Flow sensor aka the MAF is the most important sensor on our Gen 3 engines (when it comes to fueling, the Temp Sensor is King overall, ha ha). We all have heard that the engine is nothing more than a sophisticated air pump. Buying into that analogy we begin to understand how the magic of mixing the the right amount of air and fuel at the right amount of (spark) time happens.

Fuel injected engines can rely on one of two air delivery methods, using the MAF sensor or using the MAP sensor (pronounced: Speed Density). To make things even more complicated, GM decided to use both, yes at the same time. Before we get to that, let's highlight the differences.

The MAF method ~MEASURES~ the actual amount of air going into the engine at that given moment in time. Now it seems perfect and makes you wonder why the MAF sometimes gets a bad rap, I mean who wouldn't want to know exactly precisely how much air is entering the system, right? Well the MAF has a few drawbacks, first, it don't know if the air is coming or going, so it measures air in either direction as it passes through it's super duper uber sensitive wire sensor that measures air mass based on how hot or cold that wire needs to be (blah blah blah). So if for some reason a wild cam pushes some back pressure air backwards in the intake manifold guess what? the MAF measures that as if it was going in. The second issue the MAF has is with TRANSIENT (pronounced quick) throttle changes, so you slam on the gas pedal, the MAF goes WTF, same goes for when you let off the throttle pedal right quick, the MAF can't exactly keep up. Thirdly, the MAF lives about a foot and a half away from the throttle body on a cold air intake housing or some sort of plastic tube, well that's where it measure the air, so what if there is a tiny hole or leak in that housing after the MAF, ie past it, the MAF don't know anything about it, so who or what accounts for that additional air, (pronounced: vacuum leak, ha ha)

Enter the MAP. If the MAF is the Accountant in the bunch, the Manifold Absolute Pressure sensor is the Mathematician if you will. Instead of measuring the air, the MAP ~CALCULATES~ it. Well technically the PCM does the heavy lifting but the MAP feeds some crucial information into that super duper complicated formula to come up with something called Cylinder Airmass. (Google: Ideal Gas Law, or don't ha ha). Cylinder Airmass as the name implies is the calculated amount of air that arrives at each individual cylinder, not the total eight cylinders at the same time. This use of the MAP is called Speed Density, you may have heard of guys running only in Speed Density mode, and that's a topic for an entire separate discussion, it just means they disabled their MAF and don't rely on it at all (not smart for daily drivers as it castrates what makes the LSx engines such good engines). The MAP / Speed Density which uses the Volumetric Efficiency aka VE table method also has its pros and cons, such as factoring in air temp, humidity, etc. all which effects the final computation, that's why GM decided to use both.

So majority of the time our Gen 3 engines are relying on the MAF, but when we transition too abruptly with the gas pedal either on or off the PCM takes a peak at the VE table ie Speed Density to keep the MAF honest. Also according to the factory settings, above 4,000 RPM we only rely on the MAF sensor and no longer use both methods (take that Speed Density only guys, joking) as the air rushing in is more stable at that point and the readings are more accurate.

Now we are gathered here today because we most likely done did an LS Swap, in which case we altered the intake track (ditched the fugly OE air box, changed the air filter, changed to a cold air intake, changed the location of the MAF, etc.) The precise calibration that the GM engineers/technicians have done at the factory has gone out the window. This is why we start by tuning\calibrating the MAF. It sounds intimidating at first, but don't be skierd.

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

In order to tune or calibrate the MAF sensor the first thing we want to do is take our last tune file I think we left off on a file called 14 - Turn Off Cat Protection.hpt open it in VCM Editor and turn right around and save it as something called 00 - MAF Calibration - Initial.hpt yes this file will contain exactly precisely what the 14 - Turn Off Cat Protection.hpt file has in it, but it will be our fall back with a clear name of what it is.

As you will see below in the second screen shot, I actually geek out and create a separate directory for each component that I am going to tune, you can see below I created a Folder structure for MAF Calibration containing its own logs, channels, graphs, tunes, etc., but hey, you do you

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

ok, now without making any changes in the VCM Editor, simply save this file again, yet with another name, call it something like 01 - MAF Calibration - Setup.hpt and bear with me, this naming renaming files thing may seem a bit odd, but once you rinse, lather, and repeat this process a few times it will begin to sink in, it's basically that an ounce of prevention is worth a pound of cure mentality

so now in my MAF Calibration folder I show two files, the first is what I will fall back to if I jack things up too much, and the second file is where i will make my special changes to in order to setup the PCM for MAF calibration, this configuration is temporary and only for the time spent calibrating the MAF, you do not want to drive around for days, weeks, months in this temporary condition

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

You can calibrate the MAF in two ways, using either the stock narrow band oxygen sensors or using an aftermarket wideband oxygen sensor ie AFR gauge.

Option 1. Factory Narrowband Oxygen Sensor Method

To make things even more complicated, in this method you have three further choices:

1. Tune using only the Long Term Fuel Trims
2. Tune only using the Short Term Fuel Trims
3. Tune using both the Long and Short Term Fuel Trims simultaneously

PROS for all three choices above: you already own the narrow band oxygen sensors, you also have two of them, one in each exhaust pipe so you are monitoring both banks ie both the left and right cylinder heads, all the computations have already been programmed into HP Tuners by their programmers, and after tuning the PCM will use these stock narrow band sensors to operate anyway, not the wideband, etc.

CONS for all three choices above: you can not tune Wide Open Throttle (WOT) condition with this mthod, you are limited to only tuning Idle and Cruise modes aka the Closed Loop.

Option 2. Aftermarket Wideband Oxygen Sensor Method

PROS you can tune the entire operational spectrum with this method, Idle, Cruise, and Wide Open Throttle (WOT) so both the Closed and Open Loop.

CONS you have to buy (expensive) and install the wideband oxygen sensor, also if you only buy one you can only monitor one side of the engine, and anyone who's spent any time with engines knows often times both banks ie both cylinder heads do not run equally hot or efficient, (let's not fight, ha ha) and after tuning the PCM will use the the stock narrow band sensors to operate anyway, not the wideband, this is important to acknowledge because it takes under consideration how the stock OEM narrow band sensors have aged and degraded, etc.

Because this is a basic tutorial intended to wet your appetite for tuning we will be using the factory narrow band Option 1 above relying on both the LTFT+STFT special math function for the win! Nothing stops you from going at it a second time once you have a Wideband and confirming this tune and building upon it by also tuning WOT.

Re: HP Tuners Tutorials -MAF Scaling - Calibration
 

MAF Scaling - Calibration

We can take a look at the current existing MAF Calibration under Engine \ Airflow \ General tab \ MAF Calibration section in the Airflow vs. Frequency table

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

Using the Horizontal Split menu item (red arrow below) I strongly recommend you simply take a look at what the initial exponential(?) graph looks like first, if you have a virgin factory configuration it should look like a nice quarter pipe for those of you who were skaters, ha ha, no spikes, peaks, divots, valleys, just nice smooth transition

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

if someone already took liberties with your configuration and mocked it all up, here you can see before you even go making any changes yourself how bad the graph really looks

you are hoping that when you are done, yours will not look like this, ha ha, if it does, you did something wrong, or more likely you got some bad data

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

With a mental picture of our current MAF graph we are ready to put our PCM in MAF Calibration mode. In order to do that we must disable Speed Density, in other words we don't want the MAP sensor and the VE table assisting or correcting how much air is flowing into the engine, we want to solely rely on the MAF so that we can calibrate it.

To achieve this isolation we go to Engine \ Airflow \ Dynamic tab \ Dynamic Airflow section \ and set the High RPM Disable to 200 rpm

now if we glance on the help section below we can read a rather confusing description:

"[ECM] 3003 - Dynamic Airflow High RPM Disable: Above this RPM use filtered MAF airmass for airmass prediction calculations."

yet watch what happens when I only add one word:

"[ECM] 3003 - Dynamic Airflow High RPM Disable:

Above this RPM use only filtered MAF airmass for airmass prediction calculations."

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

That's it, that's all you have to do in the VCM Editor to start calibrating your MAF, the rest of the magic happens in the VCM Scanner.

What about Power Enrichment won't that skew our data? Technically we have not enabled Power Enrichment yet, as it comes crippled from the factory on these trucks, for example mine would not kick in until I was above 5,500 RPM (ridiculous I know) on some 6.0L it takes that plus being above 5,500 RPM for like 30 or 60 seconds.

If you enabled your Power Enrichment like I have you can avoid it interfering in other ways, for example, don't go above 5,500 RPM while calibrating your MAF, ha ha, or stay below what ever RPM and or throttle position you set the Power Enrichment to kick in at, so you can take care of it by the way you drive (FYI factory wants you to be above 90% throttle for Power Enrichment to kick in), you can also filter out Power Enrichment mode in the VCM Scanner when you are logging the data, we will be taking this approach. Also technically WOT puts you in Open Loop and we can't tune that with the narrowband O2 sensors anyway, it's just that slight early transition from the end of cruise and into the early start of Power Enrichment that gets skewed.

Another obstacle for us can be DFCO aka Deceleration Fuel Cutoff, this is a feature where when you are cruising and you let off the gas pedal really quickly, the computer shuts off fuel delivery to the engine (why waste fuel right) well this makes the O2 sensors read super lean for a split second and those readings can jack up our MAF calibration, again you can avoid this by not lifting completely off the throttle during MAF calibration, and this too can be filtered out in the VCM Scanner during data logging.

I like the belt and suspenders method, where we try to do both, drive accordingly (no sudden throttle changes, just smooth cruising through as much of the RPM range and load as we can get) during MAF calibration driving and also I like to rely on the filters.

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

After we made that one simple change in the VCM Editor to disable Speed Density for the duration of our MAF calibration, now we need to add some Channels in the VCM Scanner.

First I would like to show you the bare minimum of channels that it takes, we basically need two things:

1. the Mass Airflow Sensor frequency

2. the Short and Long Term Fuel trims (all four of these channels)

that's it with these five channels we can tune the MAF, however later I will tell you why you may want to add some more channels just so you have some perspective as in how fast were you going at the time, what was the engine RPM, what was your intake manifold pressure like, what position your throttle was at, were you in Open or Closed loop, etc. just some nice to haves.

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

after we have our Channels now comes the scary part now we need to setup something called a Histogram (pronounced: "graph")

we also do this in the VCM Scanner, and it will look like this (right side of the screen)

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

and here's how you build that graph

Label: you can call it what ever you want "MAF Tuning" or "LTFT+STFT MAF" whatever

Parameter: this is key and you want to select the LTFT + STFT [Math] function

View: make sure it's set to Average

Decimals: set it to 2

Function: we will talk about this later, this is a bit advanced

Cell Hits Required: make it 20 or 50 as long as it is more than 1

Shading
High Value: 20 or 25 red usually to show lean
Low Value: -20 or -25 green usually to show rich

Column Axis
Parameter: select the Mass Airflow Frequency [Sensor]

Values: cut and paste these from the MAF Calibration section Airflow vs Frequency table in the VCM Editor by right clicking anywhere in that table and choosing Column Axis / Copy Labels

Re: HP Tuners Tutorials - MAF Scaling - Calibration
 

MAF Scaling - Calibration

Once we have the Channels and the Graph in the VCM Scanner configured we need to go back to the VCM Editor and write the 01 - MAF Calibration - Setup.hpt file to the PCM. We should all be familiar with how the write aka Flashing works by now.

Then once the truck is warmed up, I like to switch to the VCM Scanner on my laptop and drive out to a place with no oncoming traffic and no stop lights, and start my calibration drive. I start driving and then press the start recording on my laptop. Then I just drive around without going into WOT. You do not need to stare at your laptop while driving. When done maybe 10 or 20 minutes later, stop the scan before you stop the drive, then come to a complete stop somewhere safe and save your log so that your laptop battery does not die.

Top Tip: if you start seeing numbers in the double digits like 13.60, 14.50, or 15.30 then you can increase your MAF calibration by something like 10%. You would do this by going to the MAF Calibration table in the VCM Editor selecting the entire table and then type 1.10 in the box on the menu and hit X to multiply. I make this suggestion right off the bat because it is dangerous to be that lean. Remember it is better to be a little rich like -2% than lean, and double digits lean is bad. So don't over think it, if your numbers are 17.20, 18.90, or 19.20 then increase your fueling by 15% so multiply the entire table by 1.15, kapish, get out of the red zone ASAP.