Ford Powerstroke Diesel Forum banner

1 - 20 of 56 Posts

·
Registered
Joined
·
458 Posts
Discussion Starter #1
Forward:
In light of the recent discussion(s) about different tuners and how they each handle various aspects of tuning (specifically, SOI timing control), combined with the fact that very few people have any real understanding of how the PCM calculates SOI, I am going to offer this information in an effort to clear up any of the mystery surrounding how the 7.3L PCM generates the SOI values. This thread is meant to be informative and educational, and as such is not the place to point fingers or start any type of battle between tunes/tuners from different companies. I WILL have moderators delete any posts that are neither a question, constructive, or informative.

Introduction:
In case anyone has any questions about my qualifications... We have almost 15 years of experience tuning the Ford EEC-V PCMs used in the 7.3L and created most (if not all) of the 7.3L calibrations that were available in the US until 2001, at which point TS Performance, Bully Dog, and a few other small companies became involved with the 7.3L chips and tuning. In 2000 we were the first to offer custom tuning for the 7.3L for modified injectors (actually, we tuned for modified injectors as far back as early 1999), compound turbos, and other mods. We have written and/or contributed to most of the 7.3L tuning tools and software that is (or has been) used by most of the popular tuners including Gearhead, Swamps, DP-T, BTS, Tyrant, TDP (Tony), and Bean's, as well as being used by Brian Jelich and Mike Ontiveros. We have the only 7.3L simulation software that will accurately provide output maps of SOI, ICP, and PWM as the PCM would calculate them. We also have the only diagnostic equipment that can correctly log actual SOI values from the OBDII port, which we have used to substantiate the graphs generated during PCM simulation. We have used real-time emulators to trace and follow the PCM functions to determine how each function/map inter-relates with other functions/maps. We have dynoed and CP-tested a variety of engine/injector configurations and not only have a solid understanding of how the PCM functions to generate SOI, but also how SOC (Start of Combustion) is related to SOI, ICP, EOT, Boost, Injector configuration (Split, Single, Hybrid, etc.), and Injector nozzle size.

Overview:
The purpose of this thread will be to provide clear, concise examples of how the PCM generates the final SOI values which are sent to the IDM and ultimately the injectors. We also plan to provide a clearer picture on how the relationship between tuning and specific modifications can affect SOC. We will be providing substantive graphical data (maps) to support our findings and will welcome any questions, either in general, or about any specific data we provide. All graphical data provided will be from either completely stock calibrations, or from calibrations in our own library. We will not be providing graphs of the actual tuning maps themselves, as this may only cause confusion if they are not properly assessed in relation to other maps. We, instead, will provide the calculated output graphs generated through our simulation software and we'll be happy to consider other data requests. We will not be posting any actual tuning graphs from a competitor's product without first receiving authorization to do so, so DO NOT ASK unless you have authorization. However, if anyone has a file they'd like analyzed we will consider posting the calculated values generated by the simulation software.

That's about it. I'll start posting the graphs and other information shortly.

Stay tuned...
 

·
Registered
Joined
·
458 Posts
Discussion Starter #2 (Edited)
Part 1: The Software

Part 1: The Software:

Okay, so where to begin? One would normally say, "At the beginning..." but I'd think that would involve a great deal of boring tuning history. Well, maybe that really is the best place because without some of that history, some of this might not make any sense. LOL

To start off, I will say is that tuning has come a LONG way from where we started back in 1997 when I was working at Superchips, and we literally had almost no idea what it was we were changing. The tools we had back then offered no graphical interpretation of the data we were changing. We didn't even know what the actual engineering values were of the data we were changing or whether it was a fuel map, a timing map, shifting map, or a limiter. It was all "HEX" data in its purest form and we were making changes with the attitude of, "Hey, let's change this and see what it does!" We were hackers in the purest sense of the word. (Butchers might have been a more appropriate word!) Below is a screen shot of the first tuning software we used:



As you can see, it's not only just a bunch of numbers, it's Hexadecimal numbers. And to make it worse, 16 bit maps like this were viewed in 8 bit formats and the bytes were reversed (what we call "Little-Endian"). But as I said, this is what we had at the time. Although, somehow we made it work. For reference, this is the Oil Viscosity Compensation table that controls injection pulsewidth based on EOT and ICP.

From these early beginnings, using archaic and almost neanderthal tools, we were able to locate and identify enough calibration data to make 60-70 HP on the OBS trucks and over 100 HP on the S/D trucks. We were also able to locate enough shifting data to significantly improve the shifting characteristics, although it's not like ANYTHING that we have today. Early tuning was almost brute force. Sort of like using a sledgehammer to open walnuts. It was effective, but maybe a little too much. Anyway, this was how it was done for over 4 years. That is, until something better came along. :D

2001 saw the introduction of new tuning tools. The first was a software tool called GUI EECTuner. This was actually the predecessor to the SCT Advantage software which was written by David Posea, and offered the first definition format which stored the address and scales of maps, parameters, and functions, and allowed for an accurate, 3D representation of maps. For the first time we were able to actually produce some sort visualization for the numerical data. I had actually used this software to some extent, and while the 3D graphs weren't all that fantastic, it was better than nothing.

Shortly after the introduction of GUI EECTuner (mid 2002 or so, I'm guessing), I had come across a website that offered a different tuning software package. The website offered an application that was completely focused on high quality, 3D representations of the Hexadecimal data. The definitions were completely customizable and all the graphical data was scalable. This software was PCMX, and is what nearly all of the Ford tuning industry has been using since 2003. Now, this software was originally targeted for Gasoline tuning, and a number of definitions already existed for Mustangs, early F-Series trucks, and other Gasoline vehicles. However, there wasn't anything yet available for the 7.3L diesel. It wasn't until 2003 that we stared taking the data we had accumulated and began building and refining defintions for the Power Strokes. We spent several months developing these definitions and just about the time that we had started licensing PCMX and selling the defintions, I was offered a job to go work with Edge Products out in Utah. At this point, basically all development on the PCMX definitions stopped. Edge had orginally intended to support all our exisiting customers and dealers, but unfortunately they let all that fall by the wayside.

Somewhere around the same time that I went to work for Edge, SCT (Superchips Custom Tuning) had been formed as a branch of Superchips that dealt specifically with custom tuning. The idea was that SCT would provide their sizable software and calibration base and Superchips would provide the hardware. Unfortunately, the joint venture quickly soured and SCT broke off and continued as their own entity. The reason this is important is that at this time, SCT started releasing the first large-scale tuning application that offered 3D mapping, spreadsheet style data, linked mapped transfer functions, and integrated support for chips and programmers. Being built on the GUI EECTuner platform (or at least modeled after it), this software still lacked the high quality 3D mapping that PCMX offfered, but since SCT offered already built, custom tunes it wasn't really necessary for anyone to actually do their own tuning and the graphical data wasn't all that important. At least nobody seemed to think it was at the time.

Now, you're probably wondering, "What's so important about 3D mapping and why do we need now all this?" On the surface, it doesn't seem like it's all that big a deal, but the reality is far from that. One example of the importance of 3D mapping is very apparent in the following images:

(click to enlarge)


The map and data on the left are an implementation of an SOI table we pulled out of an early chip from an unnamed tuner (and NO, it's NOT DP-Tuner... in case anyone feels like being a smart-alec) while the right calibration is an implementation of one of our own 80DD tunes. Looking at the spreadsheet style data, it may or may not be readily apparent that the mapping on the left is not smooth or linear. However, looking at the graphical map shows how jagged and uneven the left map really appears. By comparison, the map on the right shows to be much smoother. On top of that, the left map also shows to be really aggressive in the upper RPM range, although the spreadsheet does show the timing is aggressive as well. In any event, it's MUCH better than original way we used to tune which provided no real idea whatsoever of what the values were, graphical or otherwise. :doh:

Since the release of PCMX and SCT software back in the early 2000's, there have been a couple other applications that have been released that offer tuning in a 3D graphical format. Applications such as Paul Booth's EEC Editor (available from Moates.net), EFI-Live (which currently does not support Ford, but has a very usable interface), and a few others that escape me at the moment. The tools are getting better and better.

One thing I haven't addressed yet, but will in a coming segment, is how we use the calibration simulator to generate the output mapping which shows us the SOI Timing and Fuel PW curves we use to refine our tuning. This can be pretty in-depth stuff since it not only deals with the generated output, but also the order in which the data is processed to generate the output values. We feel that this needed its own segment due to the complexity of the processes.

Anyway, I hope that this information is helpful and gives you some idea as to why tuning today is considerably different than tuning that was produced back in the early 2000's. As the tools have evolved, so has the tuning. Of course, having the proper tools doesn't guarantee that any given person would know how to use them. There is still the issue putting the software in the hands of people that really understand how to use it: individuals that have a solid understanding of how an internal combustion engine (either gas or diesel) works and how each of the maps interrelate with each other to produce the anticipated output values for fuel, timing, shifting, and other functions, and how those outputs will affect the functionality of the engine. Thousands of mechanics use Snap-On tools, but only a few are talented enough to work on an Le Mans, NASCAR or NHRA race team while others I wouldn't let change the air in my tires.

__________

Coming up next... Part 2: The tuning hardware. Dynos, testing equipment, emulators, and how they all work together.

Stay Tuned!
 

·
Registered
Joined
·
755 Posts
Subscribed. I’ve tuned Harley Davidson’s and we stuck a “sniffer” in the exhaust to get air/fuel ratios while on a stationary Dynamometer. We used Screamin Eagle tuner key’s to change ratios based on throttle percentage, load, timing etc. We achieved a map like the ones in your picture but every bike was different. It could be the exact setup (pipes, air cleaner, cams) and the air/fuel would be similar but not the same. I’m curious to see if there are any similarities between tuning a gas vs. diesel.

Thanks for sharing the information! Inquiring minds want to know!
 

·
Registered
Joined
·
458 Posts
Discussion Starter #4
Subscribed. I’ve tuned Harley Davidson’s and we stuck a “sniffer” in the exhaust to get air/fuel ratios while on a stationary Dynamometer. We used Screamin Eagle tuner key’s to change ratios based on throttle percentage, load, timing etc. We achieved a map like the ones in your picture but every bike was different. It could be the exact setup (pipes, air cleaner, cams) and the air/fuel would be similar but not the same. I’m curious to see if there are any similarities between tuning a gas vs. diesel.

Thanks for sharing the information! Inquiring minds want to know!
In some instances, gas tuning is not all that dissimilar from diesel tuning. The biggest difference, above all else, is that gasoline, petrol, and alcohol engines adhere to a strict AFR requirement whereas diesel engines have no such requirement. Otherwise, they are both combustion/expansion type engines. Of course, spark ignition engines have a distinct, controllable start of combustion (SOC) while compression ignition engines do not. This is where we run into a great deal of trouble when tuning a diesel engine. Just because you inject fuel at a certain crank angle, there's no guarantee that the fuel will start burning at a certain crank angle. But then, that's what this discussion is about anyway. :thumb:

It's funny you should mention about identical setups not running the same with the same tuning. We see the same thing with both diesel and gasoline engines when we tune. We can get pretty close in most cases, but sometimes there just needs to be a little tweaking. It's really quite interesting.

Anyway, I hope to not disappoint anyone. I've always enjoyed sharing my knowledge and hope that people get as much from receiving it as I do from giving it. :woot:
 

·
Registered
Joined
·
3,035 Posts
Anyway, I hope to not disappoint anyone. I've always enjoyed sharing my knowledge and hope that people get as much from receiving it as I do from giving it. :woot:
Keep it coming. My inner computer geek is going giggidy giggidy gooooo! :p
 

·
Registered
Joined
·
674 Posts
Subscribed. I’ve tuned Harley Davidson’s and we stuck a “sniffer” in the exhaust to get air/fuel ratios while on a stationary Dynamometer. We used Screamin Eagle tuner key’s to change ratios based on throttle percentage, load, timing etc. We achieved a map like the ones in your picture but every bike was different. It could be the exact setup (pipes, air cleaner, cams) and the air/fuel would be similar but not the same. I’m curious to see if there are any similarities between tuning a gas vs. diesel.

Thanks for sharing the information! Inquiring minds want to know!
you will never have the same results. changes in weather. fuel type/octane will always make things change. In my turbo camaro I run a data logger that records my entire 1/4 mile run and I can make changes after each pass to the exact same tune if I see a swing in AF anywhere, or adjust the two step as to what RPM I'm leaving at to cater to track conditions. I also have different tune ups for pump gas (10#) as opposed to 118 (on 20+#) there is no exact one size fits all in tuning I have found, it's just a getting it as good as you can game, and adjust accordingly!
 

·
Registered
Joined
·
755 Posts
Well I'm patiently waiting for part II but I'm starting to come up with questions.

Now you're probably going to tell me to forget everything I know about tuning a gas engine and start over. But...... with the gas tuner you recieve feedback from the readings in the exhaust pipe. Then make changes to the VE tables based on AFR.

What gives you the feedback to know where and when to make the changes when tuning a diesel?

I have a buddy that has EFI Live for his Duramax but he has done little with it. Just downloaded a map. It would be fun to play with the tune if I had a clue on how it worked.
 

·
Registered
Joined
·
458 Posts
Discussion Starter #9 (Edited)
Hey all... I'm really sorry about the delay in posting. Corey and I have both been under the weather recently and we're just getting back in the saddle, so to speak. Not to mention that we're backed up quite a bit in the office as well. :doh:

Anyway, here is part 2 of our "PSD Tuning" series. I'll have part 3 up in another couple hours or so and then we'll open up for questions. I appreciate everyone's patience and hope that this is helpful and informative.

Thanks! :D
 

·
Super Moderator
Joined
·
31,744 Posts
Excellent info as always Bill:thumb:
 

·
Registered
Joined
·
1,699 Posts
Definately joining in on this one!!!

ANYTHING you offer is greatly appreciated!!!
:noteworthy:
 

·
Registered
Joined
·
458 Posts
Discussion Starter #12 (Edited)
Part 2: The tuning hardware.

Part 2: The tuning hardware. Dynos, testing equipment, emulators, and how they all work together:

Over the last 15 years, how we tune the 7.3L Power Stroke has improved considerably. Not only has the tuning hardware and software seen significant advancements, but the diagnostic equipment has also improved and provides a much greater wealth of feedback data than anything we could have hoped for in the '90s. Tuning for the 7.3L (or any other EEC processor based vehicle) is at a distinct advantage because these ECMs can be "live" tuned. This means that we can actually make changes to the tables and functions as the vehicle is running. This SIGNIFICANTLY reduces the amount of time spent tuning. When you consider that we can change in seconds what would most likely take days or even weeks to tune using the "chip" method, you can see why live tuning is the preferred method of tuning for any heavily modified vehicle and is even helpful on modestly modified vehicles. Coupled with high speed datalogging, we can immediately see how individual changes affect the vehicle performance. Later vehicles (2003+) such as the 6.0L, 6.4L, 6.7L and other applications don't offer the flexibility of live tuning (at least not inexpensively), but most can be reflashed pretty quickly with only a minute or two between dyno or street runs. However, since this thread deals specifically with the 7.3L, we're going to remain on that topic.

Live tuning on the 7.3L requires, at the very minimum, the use of some sort of memory emulator connected to a PC/Laptop running a related software in which changes can be made to the memory image. Ideally, datalogging software will also be used to monitor specific parameters related to the changes being made, although for certain tuning aspects such as shifting, datalogging may not be necessary. For more involved setups, additional testing equipment may be utilized. High speed Cylinder Pressure (CP) testing equipment is used by more advanced/experienced tuners to get a clearer picture of what is happening inside the cylinders during the combustion process. On a diesel, this is especially important since there is no specific, identifiable, direct relation between the Start of Injection (SOI) and Start of Combustion (SOC) and the only way to accurately determine a proper combustion cycle is to monitor cylinder pressures in relation to crankshaft rotation. Monitoring of exhaust temps is also critical, but since most trucks have a pyrometer installed already this is generally pretty well covered. Below is a breakdown of the popular tools used in tuning:

The Dyno: I'm pretty sure that by now everyone knows what this is. The dynamometer (or "dyno" as it is commonly referred to) is a device that measures the acceleration of a specific mass and uses that information to generate a power curve measured in HP (or sometimes WATTS in the case of foreign dynos). There are several types of dynos available for testing:
  • Engine Dyno: This type of dyno is set up to measure HP from an engine directly at the flywheel. This requires special setups for different engines to mate the engine to the dyno, along with additional equipment for cooling, exhaust, fuel, and other requirements. The advantage to this setup is that it allows the testing facility much greater control over the testing parameters and measure the power directly at the engine without having to deal with additional driveline losses through the transmission, transfer case, and axles. This type of dyno is generally used by engine manufacturers and professional racing facilities (such as NASCAR) in order to provide accurate HP numbers for specific engine configurations. Engine dynos are typically a "load" type dyno and frequently use a water brake to apply parasitic load to the engine, although some use an eddy current load cell to provide parasitic load. See the section below on "Load Dyno" for more information.

  • Chassis Dyno: This type of dyno allows for a vehicle to be situated so that the drive wheels spin rotating assembly. This is what most performance shops and mobile dyno services use. Chassis dynos are available in both "Load" type and "Inertia" type, with differences explained below. The disadvantage to most chassis dynos is that the HP is measured at the wheels and will always be lower than flywheel HP by sometimes as much as %30, depending on transmission type (Manual or Auto, 2WD or 4WD) and wheel and tire configurations. Larger/heavier wheels and tires provide additional parasitic losses and will regularly exhibit lower numbers than the same vehicle with smaller/lighter wheels and tires. Also, automatic transmissions will see larger parasitic losses than a similarly equipped vehicle with a manual transmission. Obviously, the biggest advantage to a chassis dyno is that you can run the vehicle without having to remove the engine, which just isn't feasible in most situations. Another advantage is that while you may not have an accurate measurement of power at the flywheel, you know exactly what is being put to the ground. This, combined with vehicle weight, can provide a pretty reasonable idea of what your ideal 1/4 mile runs will be. One final advantage of a chassis dyno is a matter of safety. With the vehicle strapped to a dyno, it's a considerably safer place to make changes in tuning than what you'd find on even the most deserted of streets. Plus, with a load dyno you can even simulate various road and driving condition, even simulating pulling a trailer. Since chassis dynos are the most popular and prevalent configuration, this provides a fairly common platform for individuals to compare performance and power numbers. Just keep in mind that no two dynos are going to give the exact same power numbers and these numbers can vary greatly between load dynos and inertia dynos as well as numbers between different dyno manufacturers. Popular chassis dynos are DynoJet, Mustang, SuperFlow, and Dyno Dynamics, with Mustang, SuperFlow and DynoDynamics being primarily load type dynos and DynoJet being primarily an inertia type dyno.

  • Inertia Dyno: In the 1990s and early 2000s, inertia dynos were the most common dyno configuration with DynoJet model 248c probably being the most popular dyno available during that era. Inertia dynos use 1 (or more) weighted drum(s) to provide a specific load against which the vehicle must accelerate. HP is measured based on the amount of time it takes to accelerate the roller(s) and then is output as a power curve over time, vehicle speed, or engine speed. For light, naturally aspirated or supercharged vehicles, this often provides accurate and consistent power numbers. However, for heavier turbocharged vehicles, inertia dynos may not be consistent or accurate as the inertial weight (usually around 4,000 Lbs.) often doesn't provide enough load to simulate a 7,000 to 10,000 Lb. vehicle. This frequently results in inadequate boost generation and lower power numbers. There is also some debate over the accuracy of these dynos at higher power numbers, but that is outside the scope of this dicussion.

  • Load Dyno: A load dyno can be configured as a load cell alone, or a load cell combined with an inertial mass. Most engine dynos use a load cell by itself while most chassis dynos are a load and inertia combination. Load cells are used to provide a variable load in order to test power under different situations. Early engine dynos used a water brake to absorb power while most later engine and chassis dynos use an eddy current (electrical) brake absorption unit. A load dyno offers significant advantages over a plain inertia dyno as they can be configured to accurately simulate vehicle characteristics under a variety of test conditions. Because of this, most consider a load dyno to provide a more accurate power measurement, especially on heavier, turbocharged vehicles. With additional loading, the turbochargers are more effectively utilized and a more accurate power number can be achieved.

  • Accelerometer: These are considerd the "poor man's" dyno. While not technically a dyno, these can be used to calculate power output based on vehicle acceleration as well as provide a pretty accurate 1/4 mile run. G-Tech is probably one of the most popular manufacturers of these devices and their units are pretty inexpensive at around $200.00.

For a more detailed breakdown and description of dynos, there is a good article on WikiPedia about Dynamometers.

Tuning Software: Realistically, without tuning software this discussion wouldn't even be possible. Without the ability to make changes to the binary images used by the PCM there wouldn't be any chips, programmers, or custom tuning. Tuning software has been continually improved and now has more feature and functionality than ever before. When you consider where the industry was 15 years ago, it's surprising that we were able to achieve anything at all. As computers and software have advanced, so did the quality of the tuning. Today's tuning software provides multiple methods of visualization, ranging from "spreadsheet" views which work with tables of data, to full, 3D graphical representations of the binary data which clearly illustrate maps and curves in a form that most people can look at and understand to a fair degree. It's partly because of these improvements in tuning software that today's tunes are more powerful and more reliable than ever before.

The Emulator: These devices are used to effectively replace the ROM (memory) image on the PCM with an image that is stored on a PC/Laptop. This allows changes to be made on the PC/Laptop and those changes will be directly translated to the emulator which causes the PCM to immediately run from the new changes. When making adjustments to fueling, timing, shifting, idle, or other functions, this helps to save time by effecting changes in real time and more quickly reaching the desired target values. More involved devices not only allow live changes but also provide feedback to the PC/Laptop application as to what areas of a specific map or function are currently being accessed by the PCM and the software then provides a visible indication of these locations. This is commonly referred to as the "bouncing ball" and helps to indicate where changes need to be made based on current operational conditions. Some emulators are self powered and can continue to function as a standalone chip when not connected to a PC/Laptop, which means that it can run on the last settings provided without having to actually burn a chip with the final working image. Emulators are one of the most important tools used by a tuner as it provides an exponential increase in speed and flexibility.

Cylinder Pressure Testing Equipment: This equipment is used to get a snapshot into the actual combustion process. It consists of pressure sensors that are mounted in such a fashion that they can record cylinder pressure (usually situated in the glow plug holes on a diesel) and extremely high speed datalogging equipment which can record thousands of samples a second to provide a very clear profile of the combustion process. This information is then used to determine the relation between Start of Injection (SOI), Start of Combustion (SOC), Crankshaft Angle, and other parameters, and then that information can be used to achieve optimal fueling and timing parameters under specific operating conditions. This equipment is extremely useful in developing calibration profiles for certain modifications such as performance injectors, modified/multiple HPOP setups, compression changes, airflow/turbo/camshaft changes, and other modifications that will have an effect cylinder pressure and SOC. TFX Engine Technology provides a very good package, but because this equipment is extremely expensive it is generally cost prohibitive for most tuners.

Datalogging Equipment: This equipment is extremely helpful in providing valuable feedback to changes in tuning, especially for fuel control changes such as Injection Pulsewidth and Injection Pressure, and should be considered standard equipment for anyone performing any kind of tuning on a vehicle. Equipment ranges from simple standalone devices such as the ScanGuage, Insight, DashDAQ, or the Ford NGS (Star Tester), to devices coupled with a PC/Laptop such as AutoEnginuity, AutoTap, LiveLink, Ford IDS, PCMScan, Eye Spy and many others. Most (if not all) of these will provide datalogging (or at least data monitoring) of critical parameters as well as reading and clearing of Diagnostic Trouble Codes (DTCs). Most inexpensive datalogging devices will have a fairly low data sampling interval, usually around 5 Hz (samples per second) and is fairly adequate for most hobbyist tuners. More expensive applications such as the Ford IDS or Eye Spy provide a much higher sample rate of around 500 Hz and yields a much more detailed image of what's going on. If you are considering getting into any heavy tuning or if your vehicle has significant modifications, you may want to consider going with a high speed setup as the resolution is much, much better.

This pretty much covers the basics on tuning equipment. As you can see, getting into tuning can be a pretty expensive enterprise, and that's just from the equipment aspect. The cost of training should also be considered, and in some extreme cases, the cost of experience (ie. blowing and engine). Most diesels are pretty forgiving, but it doesn't take much tuning to cause a runaway engine. Even a simple SOI curve that is too aggressive can scatter a bottom end in short order. Yes, experience can be pretty expensive so don't overlook that. We've been fortunate in the fact that the only engine we've ever damaged on the dyno was actually from a cylinder wall failure (crack), which ultimately had nothing to do with the tuning. Every major tuner out today has had customers that have suffered engine failures while running their tuning, as evidenced by our engine failure survey, although the number of failures has declined in recent years specifically due to improvements in tuning quality.

__________

Up next, the meat and potatoes! Part 3: Tuning Maps, SOI, SOC, and other stuff.

Hang tight!
 

·
Registered
Joined
·
458 Posts
Discussion Starter #13
Well I'm patiently waiting for part II but I'm starting to come up with questions.

Now you're probably going to tell me to forget everything I know about tuning a gas engine and start over. But...... with the gas tuner you recieve feedback from the readings in the exhaust pipe. Then make changes to the VE tables based on AFR.

What gives you the feedback to know where and when to make the changes when tuning a diesel?

I have a buddy that has EFI Live for his Duramax but he has done little with it. Just downloaded a map. It would be fun to play with the tune if I had a clue on how it worked.
Jason,

The 2 major differences between diesel and gas tuning are:
  1. Diesels don't follow any AFR rules.
  2. Diesels DO NOT have a specific, identifiable Start of Combustion point.
Outside of that, they're not all that dissimilar from gasoline engines. They still have a timing curve and can suffer "detonation" or "pre-ignition" like a gas engine, but where a gas engine "throttles" the airflow to control engine speed and power output, a diesel "governs" engine output and speed by controlling fuel flow through the injectors. No AFR concerns... Just add fuel and you make more power, at least until you consume the air ingested in the cylinder. Then all you end up with is heat and smoke. :wink[3]:
 

·
Registered
Joined
·
1,699 Posts
Could we break down how the sensor inputs affect the pcm outputs?
What is the pcm actually doing with the inputs that it receives?

I understand most of them in a gasser but would like to get a better grasp
on the diesel world.
 

·
Registered
Joined
·
458 Posts
Discussion Starter #16
Could we break down how the sensor inputs affect the pcm outputs?
What is the pcm actually doing with the inputs that it receives?

I understand most of them in a gasser but would like to get a better grasp
on the diesel world.
We're getting to that in Part 3.
 

·
Registered
Joined
·
1,699 Posts
Haha ok!:thumb:

Patiently waiting......:eek:hnoes::eek:hnoes::eek:hnoes: HAHA
 

·
Registered
Joined
·
458 Posts
Discussion Starter #18
Part 3: Tuning Maps, SOI, SOC, and other stuff.

Okay, so it took longer than I expected to get back to this and get it finished. There always seems to be something going on around here and there's just not enough hours in the day. But life goes on and sometimes you gotta say, "What the f***." For part 3 of our installment, we're going to cover SOI (Start of Injection), how it relates (or sometimes doesn't relate) to SOC (Start of Combustion), and how the PCM uses all the fancy tables at its disposal to generate the all-but-misunderstood SOI. So without further ado (da, ado-da), we bring you more of those pretty, colorful pictures that everyone loves!


As I mentioned earlier, when we started tuning these trucks back in the late '90s, we literally had no clue what we were changing. Everything was basically a best guess as we would change some values, dyno the truck, and then see what happened. Eventually we were able to identify tables that would relate to fueling, timing, and ICP, but still really didn't have any idea what those values actually were. We were changing HEX numbers by percentages and didn't have any actual engineering values to reference our changes. Pretty stone-age, eh? LOL

Fast forward a few years and we start to see the first of the graphical tuning applications for the Ford PCMs. Most of these were centered around the Mustang and F150 vehicles, but it offered us a bit of insight into how Ford used multiple table and temperature offsets to handle certain fueling and timing characteristics. Also around this time we were able to procure some documentation that helped break down some of the more useful functions and tables, and this information helped to set the base for much of the tuning software that is currently available for the Power Stroke. Coupling the acquired information with live tuning capability, we were able to see just how changing specific functions would affect fueling and timing, and also generated a better understanding of functional priority as well as functional accumulation. Understanding the order in which functions are processed as well as how the outputs are accumulated allows those who understand these processes to provide higher quality, better performing, and safer calibrations. Without that understanding, it is very easy to go out of range on Injection PW or SOI Timing and end up, in extreme cases, with a $10,000 paperweight.

There is a LOT of data to consider when tuning, especially the effects that changing one function has on the output of another. For example, the Start of Injection Delay looks at ICP and EOT, as oil temp and injection pressure have a direct effect on WHEN the actual injection event occurs once the injector is turned on. This table is a crucial component of the SOI calculation and is often the most misunderstood. Since this table is dealing with an electro-mechanical delay, it is actually calculated in ms (milliseconds) versus the standard CAº (crank angle degrees). Because this is calculated in time, the actual CAº varies with RPM, roughly about 6º per ms per 1000 RPM. So, at 2000 RPM the offset is about 12º per ms and at 3000 RPM the offest is about 18º. The offset table considers ICP and EOT and provides this base output value upon which all other timing calculations are added. Here is what the SOI Offset table looks like:

Start of Injection Offset - Stock

(click on image to enlarge)


What is important to understand about this table is that this is quite often the table that many tuners adjust to control SOI Timing. Where this is a concern is that when tuning this table, you MUST take into consideration what your ACTUAL ICP is at or you can run into a severe problem. We've seen a number of tables like this:

Start of Injection Offset - Economy

(click on image to enlarge)


The problem with this situation is not necessarily that the electrical offset is excessive (it is a bit, and to be honest we've used tables like this in the past as well...), but that it scales down considerably as ICP decreases. The reason this is a problem is that with some tuning there maybe a loss of ICP due to excessive Inj. PW, worn injectors, weak HPOP, or bad IPR. If the vehicle is tuned for this condition and the timing is set accordingly, any change in ICP will yield a change in SOI. And to make matters worse, the problem is compounded by an even greater change in SOC as well. Consider this situation (and this is NOT an uncommon situation):

Under hard acceleration, a tuned truck is requesting a conservative 4ms of injection pulsewidth. Despite the fact that the ECM is requesting 3000 PSI (20.5 MPa) of ICP, the ICP starts to fall off and approaches somewhere in the area of 2400 PSI (16.5 MPa). This causes a shift in the SOI Offset table from 1.6 ms to 1.4 ms, or 1.2º degrees per 1000 RPM. Even at 3000 RPM, this only comes out to 3.6º difference which really isn't that big a deal. The problem is that the related loss in ICP produces a cooler, slower injection event and results in a later SOC event... Considerably greater than just the 3.6º lost from the SOI Offset shift. Now take that same vehicle and tune and change the HPOP (as is often advised by tuners to "resolve" the low ICP issue, even though the tuning is often at fault). Now you are able to maintain 3000 PSI ICP and your 3.6º of SOI is restored, along with a hotter, faster injection event. This results in an SOC that changes more than the 3.6º shift in SOI. In fact, CP (Cylinder Pressure) testing has shown that a 500 PSI change in ICP can result in 5º to 12º of change in SOC, and sometimes even more depending on the SOI point. Combined with the original 3.6º SOI shift, that anywhere from 8º to 15º of change in the combustion point, just by changing ICP 500-600 PSI.

This fact alone has caused more engine failures than any other condition, mechanical or tuning. Ask most people when their engines failed and they'll tell you, "It was just driving down the street. I wasn't even at half throttle." This is because in most of these situations, full throttle conditions actually resulted in a loss of ICP and ultimately a reduced SOI and SOC as well. The failures came under moderate driving conditions where ICP was high and SOI and SOC were much higher.

Now, the rest of the SOI tables are calculated in CAº so these are easier to understand and put a finger on. These values are calculated out and are cumulative against each other based on specific operational parameters. Some relate directly to EOT (Engine Oil Temp.) and RPM, other relate to MFD (Mass Fuel Desired) and RPM. All of these need to be addressed in order to produce calibrations that are responsive in all driving conditions and under all temperatures.

When considering SOI, it is very important to remember that SOI DOES NOT DIRECTLY relate to SOC. A 3º change in SOI can often result in a 4º, 5º, or greater change in SOC depending on the crank angle, injection pressure, aircharge temperature, boost, block temperature, and other factors. This is why it is extremely important to have quality datalogs to validate all operational conditions and to ensure those conditions are stable within the confines of the tuning. If ICP is not stable, the tuning must be rectified to ensure that it is, otherwise the result could range anywhere from a poorly performing vehicle all the way to engine failure. If you cannot adequately anticipate the conditions, you cannot properly tune the vehicle.

These examples below are taken from a recently rebuilt 7.3L with little more than standard machine work, new stock pistons, a stock cam, stock heads, 250cc/200% injectors, and a GT38R turbo. This combination produced 543 HP at 85ºF and an impressive 566 HP at 55º F. Here are some screen shots of the tuning curves from the program as produced through AnalyTune. Samples are taken at 190º EOT, at which the engine was dynoed at.

Injection Control Pressure

(click on image to enlarge)


Injection Pulsewidth

(click on image to enlarge)


Start of Injection Timing

(click on image to enlarge)


Keep in mind that these are "DESIRED" values. While SOI and PWM values are consistent between desired and actual, ICP values may vary depending on the capability of the HPOP. It is extremely important to look at the generated values from the datalogs to ensure that the "DESIRED" values and the "ACTUAL" values correlate. In looking at the resulting datalog recorded during the run (below), you can see that not only was the ACTUAL ICP stable and comparable to the DESIRED ICP throughout the run, but even the recorded SOI is right in line with the anticipated SOI from the above graphs.

Datalog - 140x_stage_3_final.xls

Also keep in mind that this is done WITHOUT forcing a maximum SOI Limit like some other tuners do (usually around 35º BTC). This means that this vehicle will run just as well when cold as it does hot. Under normal circumstances, the ECM will advance timing considerably when cold. For example, at 50º F, the SOI Timing curve would look like this...

Start of Injection Timing @ 50º F

(click on image to enlarge)


This is the difference between the two files....

Start of Injection Timing @ 50º F vs. 190º F

(click on image to enlarge)


The SOI Timing difference is considerable, and clamping the SOI on vehicles that run in colder climates can translate into noticeable cold-start and cold running issues, excessive white smoke, and considerable loss of performance until the engine reaches normal operating temperature. These engines need advanced SOI Timing when cold to offset the low compression temps, cold air charge, cold fuel spray, and even the inherent injection delay cause by the increased viscosity of the cold oil. Obviously, the best approach is to let the PCM handle the SOI in the manner in which it was designed for the best drivability in all situations.

As we've already stated, SOC is not directly related to SOI. This is because the fuel spray relies on the temperature of the compressed air mass in order to ignite. Even a small change in crank angle can have a dramatic effect on the specific temperature of the air mass at the point of injection and can advance or retard the point of combustion. When you take into consideration factors such as block temperature, ambient temperature, aircharge temperature, boost, intercooler efficiency, fuel temperature, injection pressure, spray pattern, atomization, and other minor factors, it becomes a real challenge to identify any sort of SOC point... At least without appropriate CP testing equipment. It is in this that experience has as much to do with tuning as equipment. Historically, there have been a number of ways to approach tuning that vary from the scientific (Dataloggers, CP testers, and other diagnostic equipment) to the downright mystical "experienced tuner's ear". Over the years we've used a combination diagnostic equipment, experience, and just plain old common sense. With nearly 30 years in the automotive performance industry and 15 years in tuning the Ford Power Stroke, we've seen and tuned a wide variety of combinations and have accumulated a wealth of knowledge from every truck we've tuned. We've learned simple tricks to tuning just by using a boost and EGT gauge, and we've developed an ear for adjusting SOI based on the "sound" the engine makes under load. It is this experience that allows people to be able to push beyond normal thinking... To think outside the box and be able to look at a setup and help it to reach its maximum potential. Legends like Smokey Yunick used as much intuition in his approach to racing as he did tools and equipment. There is no question that there is an art to tuning, and some people just seem to "get it" better than others.

Anyway, that about sums up the topic of SOI and SOC. The relationship of Injection PW and ICP is a simple a mater of Fluid Dynamics and can already be easily calculated so there's not much reason for me to elaborate past the point that ICP is derived first and then the Injection PW is determined based on the amount of ICP produced. Pretty straightforward.

I hope this information is helpful. If anyone has any questions, I would be more than happy to answer them for you. Please post them here (do not PM) so that everyone can benefit.
 
  • Like
Reactions: jonbar87

·
Registered
Joined
·
1,699 Posts
Ok, this is going to be a relatively bland question when asked after all that!

How much difference will running 5w40 oil with a tune setup for 15w40 behave when the engine isnt at operating temp?

Also, how does the ebps affect pcm output?
 

·
Registered
Joined
·
458 Posts
Discussion Starter #20
How much difference will running 5w40 oil with a tune setup for 15w40 behave when the engine isnt at operating temp
Running a lighter oil will help improve cold drivability with basically no effect on warm drivability. In fact, I run 5w30 year round in my truck with no problems at all.

Also, how does the ebps affect pcm output?
EBP is used by the ECM to calculate load, which in turn controls torque calculations and boost. The torque calculations then control the shifting characteristics and the boost controls fueling characteristics.
 
1 - 20 of 56 Posts
Top