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Tuesday, September 15, 2009

EFILive Diesel Tuning for a Common Rail Diesel Engine

We buy diesel pickups because we appreciate the simple pleasure of push-you-back-in-your-seat torque. As long as it smokes, whistles and stinks, we assume it is running like it should. The details of engine operation are somebody else’s job. Why worry about how long our fancy electronic injectors pulse open or how our variable geometry turbos go about tightening their exhaust housings to supply our engine with just the right amount of boost? The answer is because now you can control it! Lean in a little closer… Enthusiasts no longer have a screwdriver-carburetor relationship with the power parts on their diesel trucks. Long gone are the days of throttle cables, wastegates and mechanical injectors. Computers are officially running the show.

Hold on, before you go out and buy a fifth of Southern Comfort, consider this: where there is a computer, there is software, and where there is software there is hope. We have software. It is called EFILive. What’s more, the Duramax is the only new diesel with software available to you, the user. I will wait while you laugh at the Dodge and Ford guys in the room. Some of the skeptics out there are probably saying “Yeah, we know its computer-controlled, that is why we have programmers and modules to tune it. What is so great about this software?”
The greatness lies in the wide range of parameters that users now have control over and the fine tuning tools the software offers users.
While typical module and program type boxes allow the user to select something like:
Stage 5/150 HP
Once you have selected this setting, the module makes all the decisions for you.
EFILive’s custom diesel tuning software, on the other hand, allows the user to do something like:
  • Ramp in 70% more fuel
  • Eight pounds of boost
  • 12 degrees of timing in range from 2,800 to 3,500 RPM.
Then the software records all of the truck’s parameters, allowing you to verify your changes on a test drive or pass down the drag strip. The above example is not a stretch of EFILive’s capabilities: you are now the master of your Diesel Domain.
By now, most guys are either really scared of potential mistakes one might make with such a powerful tool or really excited about the possibilities. My advice? Relax and take your time. It is important that users know their limits and respect their new found power or they risk breaking expensive parts. Nobody wants to wait for a tax return check to get back on the road. The following is a short guide to help new users learn what is involved with proper use of EFILive.

EFILive Diesel Tuning Basics

The costly part of this package is the hardware ($799.00). There is a black box and two cables that connect your laptop computer to the truck. The Flashscan V2 is the fancy name for the black box. It stores all licensing information and has some stand-alone features such as code reading and black box logging. It is your link to your truck’s brain. This cable allows you access to the engine control module (ECM) using EFILive’s software, which is available as a free download from www.EFILive.com. The software remains in demo mode until you enter the license information. After downloading and licensing the software you should get connected to your truck using your laptop and Flashscan. The first step is to read GM’s factory program on your truck. This will allow you to display the tune file you have been working with before any changes are made. The file (also called the tune or calibration) contains all of the maps used by the truck’s computer to determine its behavior under any given situation.
These maps, or tables as they are also called, contain the information that we will tweak in order to change the way the engine and transmission behave. After making adjustments, we will save the file before flashing it to the truck. The read-adjust-save-flash cycle will become very familiar to you as you spend time with the edit software. Subsequent cycles will not require the read step since the existing tune can simply be flashed (copied over) with the new file.

Flashing an LB7 Duramax with EFILive Diesel Tune


Building a Diesel Tuning Fuel Curve

The diesel engine is throttled by fuel; no throttle blades here. When fuel is commanded into the engine and burned adequately, it produces torque. The amount of torque produced by the engine at any given RPM constitutes its horsepower output. Our job in diesel tuning the engine is to command a smooth fuel curve so that as the throttle input and RPM come up, the driver is able to predictably control power output. Aggressive fueling at low throttle input makes for a touchy throttle pedal; however, if you under-fuel you get low throttle sensitivity and the truck feels lazy. Ideally, we would like to see power output consistent with throttle position. Tuners should work to build a smooth fueling curve which tapers down with RPM. This is true because as RPM rises it takes less torque – and consequently less fuel – per stroke to maintain horsepower output. Consistent horsepower output relative to throttle position is the ideal for drivability.
Picture of factory torque based fueling map viewed through EFILive. Highlighted row represents engine torque command at 40% throttle input across RPM.
Bottom picture represents the same table as the top converted into horsepower for a visual representation of the horsepower slope compared to the torque slope (all else equal). Fuel curves can be adjusted using the throttle based injection quantity, pulse-width, and pressure tables. Fine tuning can be accomplished through a variety of limiting tables.
Actual fuel quantity injected can be visualized as a cube, with one side representing the injector nozzle size, one side representing fuel pressure and one side representing the pulse-width or the length of time the injector is open. Modifying any of these sides will change the volume of the cube, that is, the volume of fuel injected and, likely, the engine torque.
The algorithm for commanding a fuel quantity is roughly as follows:
First, the throttle base injection quantity table is used to command the base fuel volume relative to engine RPM and throttle position. This starting value then goes through a maze of limiting tables which trim for emissions, torque and revolution range as follows:
  1. Fuel volume is compared to Mass Airflow (MAF) reading to determine if limits need to be applied based on airflow requirements. See the MAF limited injection quantity table.
  2. Fuel volume is compared to max fuel injected (warm) limit to determine if general fuel limits apply. 
  3. Engine/transmission torque limiting tables and their corresponding fuel tables are referenced to determine if fuel should be limited based on torque limits. 
  4. Engine RPM is checked. If engine is at the rev limiter, fuel rate will be cut to avoid engine over speeding. 
  5. The result of the throttle base injection quantity command after it is passed through the limiting tables is called the main injection rate. This is the volume command (mm3) all other tables will use as a reference. 
Second, the main injection rate or volume of fuel per injection event (mm3) is used as a reference in the base fuel pressure table to define the commanded fuel pressure for the engines current operating state.
Here are some important notes on fuel pressure.
  1. Commanded fuel pressure is not always equal to actual fuel pressure. 
  2. Actual fuel pressure is related to fuel pressure regulator voltage, low side fuel pressure, engine RPM as the pump become less efficient as RPM increases, and of course the fuel usage load commanded by the tune. 
  3. All fuel pressure related calculations in other tables are made using actual fuel pressure measured at the rail, not commanded pressure. 
Third, once actual fuel pressure and main injection rate have been defined, injector duration can be calculated using the pulse-width tables. Increasing the pulse-width at any point in the table will effectively increase the length of that side of the cube. The amount of fuel delivered, measured in mm3, will rise accordingly. In all of this, it is important to understand that volume command (mm3) is simply a reference tool to help us define fuel pressure and injector duration. Fuel pressure, pulse-width and nozzle size determine actual volume (mm3).
The fuel curve is the single most important factor in the smoke output of the truck. Commanding big fuel by ramping up throttle base injection, pulse-width or by disabling (maxing out) the MAF limiting tables before the turbocharger spools up will cause a fuel rich environment that results in a smoky tune. An efficient fuel curve should be matched to the turbocharger’s capabilities and limitations. Neglecting this principle will result in an engine that runs hot and that is hard on expensive parts. You should know the EGT/time limits with which you are comfortable. Hard parts are another consideration when designing a fuel curve. Fuel makes torque. Torque can hurt parts. There is a reason that GM put torque-limiting tables in their factory calibration. They know that they can make parts last by producing power at higher RPM with less torque. Remember the expression for horsepower means RPM can be used instead of torque to produce power.

Diesel Tuning: Limiting Torque

Let’s look a little deeper at how torque limiting tables work. As part of the development stage used to create the table, the engine is first run on a dyno at all points of its fuel calibration map. The calibration engineers then match the fuel reference (mm3) to a corresponding torque number expressed in foot-pounds. Once these relationships are known, the calibration engineers build a base torque table and a torque-limited injection quantity that allow the engine controller to relate fueling to torque output. If the powertrain development team says they need to limit torque on a specific part of the drivetrain, say the transmission, the calibration team can simply enter this limit into the calibration parameters at whatever point it applies. They don’t have to worry about limiting fuel because they have already defined the relationship between torque output and fueling within the calibration. So, when one of the torque-limiting tables call for a torque limit, that torque limit is referenced to the torque limited injection quantity table and the fuel reference (mm3) is consequently trimmed. Once we have changed the pulse-width and pressure tables of the tune, there is no way for GM to accurately limit torque output because we have effectively changed the volume of fuel associated with the mm3 reference.

RPM

200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
3400
3600
3800
4000
4200
4400
4600
4800
5000
mm3 Per Stroke
0
-14
-29
-43
-43
-44
-46
-50
-55
-59
-63
-70
-77
-83
-95
-107
-114
-114
-114
-114
-114
-114
-114
-114
-114
-114
10
17
34
52
40
27
27
27
38
18
-1
-13
-21
-23
-38
-51
-58
-58
-58
-58
-58
-58
-58
-58
-58
-58
20
41
81
122
108
93
98
90
80
72
66
49
46
37
26
5
-10
-10
-10
-10
-10
-10
-10
-10
-10
-10
30
63
126
190
193
180
161
154
157
166
175
166
180
179
166
145
128
128
128
128
128
128
128
128
128
128
40
84
169
253
241
259
239
230
249
250
252
224
257
258
238
224
210
210
210
210
210
210
210
210
210
210
50
96
192
289
312
320
329
334
335
337
339
330
320
304
288
272
260
260
260
260
260
260
260
260
260
260
60
109
218
328
345
362
371
379
399
402
406
401
387
373
349
329
315
315
315
315
315
315
315
315
315
315
70
137
247
358
376
395
404
433
454
466
478
475
460
437
409
390
376
376
376
376
376
376
376
376
376
376
80
181
292
402
417
432
439
470
505
520
536
531
531
509
472
441
443
443
443
443
443
443
443
443
443
443
90
218
328
439
454
469
476
509
542
557
572
568
568
564
548
550
568
568
568
568
568
568
568
568
568
568
100
218
328
439
454
469
476
509
542
557
572
568
568
564
548
550
568
568
568
568
568
568
568
568
568
568
110
218
328
439
454
469
476
509
517
524
539
546
550
564
548
550
568
568
568
568
568
568
568
568
568
568
120
218
328
439
454
469
476
509
517
524
539
546
550
564
548
550
568
568
568
568
568
568
568
568
568
568


rpm

200 
400 
600 
800 
1000 
1200 
1400 
1600 
1800 
2000 
2200 
2400 
2600 
2800 
3000 
3200 
3400 
3600 
3800 
4000 
4200 
4400 
4600 
4800 
5000 
torque
-18 
1
2
3
3
4
4
4
4
5
7
9
10
11
14
17
18
18
18
18
18
18
18
18
18
18
74 
4
9
14
15
18
17
18
19
20
21
22
22
23
24
25
26
26
26
26
26
26
26
26
26
26
185 
9
18
27
27
29
31
32
32
31
30
31
29
29
31
33
35
35
35
35
35
35
35
35
35
35
277 
14
29
44
44
41
43
43
42
42
42
44
41
42
46
49
51
51
51
51
51
51
51
51
51
51
369 
23
47
71
65
60
57
56
54
54
52
54
56
58
62
65
67
67
67
67
67
67
67
67
67
67
461 
31
62
94
90
86
84
76
70
68
67
67
69
72
77
81
81
81
81
81
81
81
81
81
81
81
554 
31
62
94
90
86
84
101
91
87
84
83
82
87
90
90
89
89
89
89
89
89
89
89
89
89
646 
31
62
94
90
86
84
101
91
87
84
83
82
87
90
90
89
89
89
89
89
89
89
89
89
89
738 
31
62
94
90
86
84
101
91
87
84
83
82
87
90
90
89
89
89
89
89
89
89
89
89
89

Boost Command: Fuel + Air = Fun

A modern diesel engine will not dance unless the turbocharger sings harmony. In order to make a smooth, efficient tune we need to command the air supply to match the fuel supply. This is especially true in variable-geometry-turbo (VGT) equipped trucks where it is possible to make more than a simple wastegate adjustment. The Duramax uses a variable geometry turbocharger in all trucks built after 2004.5 (VIN 2). Variable geometry turbos work on a feedback loop to match actual boost to commanded boost. The turbo looks to the trucks computer for a boost pressure command and then adjusts its turbine vanes to meet that command. The turbine vanes can be tightened or opened in order to adjust the force applied to the turbine wheel. If the current boost pressure is below the desired value, the exhaust vanes will tighten up to spin the turbine faster until the actual boost equals the desired boost. The tuner will know he is close to desired boost when the truck is running clean (no smoke). Adding more boost than necessary reduces the engine’s efficiency by creating an excessive exhaust restriction, or pull, on the engine. A tighter turbine housing increases the drive-pressure of the exhaust on the turbine wheel at the cost of overall exhaust flow through the engine. There is a balance to be reached between drive-pressure and exhaust flow. Using less boost than required by the fuel command will cause high EGT and sluggish performance. Be cautious about running the factory turbocharger above 35 pounds of boost (at sea level). It is unlikely that you will increase power past that level unless you step up to a bigger charger. The drive-pressure/compressor-efficiency balance will tip to inefficient somewhere between 32 and 36 pounds of boost near sea level. Here are some steps for you in order to add boost compensation for added fuel:
First, make note of the section of the tune where you added fuel. If you have only added pulse-width into the tune at 70mm3 and above, there is no sense in commanding more boost in areas under 70mm3 because those remain unchanged at stock fueling values. Adjust boost only in areas of the map where you adjust fuel.
Second, the factory calibration runs clean. Tuners are often able to add fuel on stock boost levels without making a noticeably smoky tune. Use your eyes, the less boost you need to make the tune clean, the more efficiently your engine can run.
Modified pulse-width table from 50mm3 up
Modified Boost table to compliment modified pulse-width table (50mm3 up) 
Third, if you have determined the calibration has enough extra fuel to warrant more boost, then use the desired boost tables to raise the commanded boost pressure (adjust both EGR on and EGR off). The manifold air pressure sensor (MAP) uses this table to adjust turbine vane position within the minimum and maximum vane limits in order to reach the desired boost command. Desired vane position tables mean very little to the tuner.
Understand that your desired boost table accounts for ambient air pressure and actual boost pressure (barometric pressure in PSI plus boost pressure in PSI).
Work in percentages and smooth areas of edit. If you have added 40 percent more fuel, you might command 15 percent more boost in the same area of the map (with regard to mm3 and RPM) and then take the truck for a test drive. Commanding over 47 (33 PSI boost) is usually not productive unless you are using a larger compressor or non-stock turbo.
Fourth, Always perform a sanity check! When adding boost we need to check turbine function (vane position), smoke output and exhaust gas temperature in order to gauge progress.
Log turbo vane position during your scans and compare them to your max turbo vane position tables in the tune file. If the numbers match, the turbocharger is probably unable to reach your boost command using the stock maximum vane position table. Do not raise the maximum vane position limit unless there is reason. Continuing to tighten the exhaust housing simply to run more boost is an inefficient strategy that can lead to turbine failure. Typically this scenario is caused by insufficient engine speed (raise shift points) or over-aggressive fueling down low. Avoid both by not lugging the engine or fueling aggressively down low.
Keep an eye on the tailpipe. Shoot for a clean pipe at cruise and light throttle, and a grey pipe under heavy load. This is usually as good as it gets using factory turbochargers. Soot at cruise is a sign that the truck may need a higher boost command. Heavy soot under load is an indication of significant over-fueling (pulse-width too long), low boost, or low timing.
Tune for appropriate EGT. These usually follow smoke output. High EGT typically show up in a fuel-rich condition and can be an indication that commanded boost is too low. Believe it or not, it is possible to run too cool as well. When EGT are low under load it is a sign that the engine is ingesting more air than it needs. Extra air comes at the expense of turbine energy (horsepower) and is unnecessary. Shoot for EGT between 650°F (light cruise) to 1300°F (loaded pulling). If EGT are higher than expected, it is a sign that boost may be low, timing is not advanced enough, or the vehicle is operating at maximum capacity. Time spent at 1500°F-plus should be limited to racing and sled pulling. Sustaining temperatures this high for 30 seconds or more greatly increases the risk of damage to internal engine parts.
Fifth, an important note on altitude: It may seem reasonable to think that a compressor that can make 32 PSI of boost (47 MAP) at sea level could make 32 PSI (40 MAP) at altitude, after all the difference of eight PSI in ambient pressure has been accounted for by the lowered desired boost. This is not the case on a compressor near the end of its efficiency map.
Turbochargers don't react linearly as ambient pressure drops. They react in ratio. A factory LLY compressor is maxed out at a 3.2:1 pressure ratio. That means that the air on the intercooler side cannot be much more than 3.2 times the total pressure at the compressor inlet. At sea level (14.7 psi ambient) this is ~47MAP or ~32 PSI boost. However, at high altitude – when starting with eight PSI ambient – 3.2:1 pressure ratio is more like 26MAP. This puts boost at 18 PSI for maximum efficiency of the compressor. Looking at a compressor map, you will see that at altitude it takes more shaft speed to raise the pressure ratio while also lowering the compressor’s efficiency (heating the intake charge). If you command 32 PSI boost pressure at high altitude where eight PSI is ambient pressure, you'll be commanding a 5:1 pressure ratio. Compare those two efficiencies on the compressor map I referenced. Five to one is “off the map” as they say. This is sustainable for a short while but could easily lead to parts failure or overheating with prolonged use as the poor efficiency of the compressor pushes heat into the intercooler and then the radiator.
Sixth, a word to the wise: the commanded boost is only as good as the MAP sensor feedback to the ECM. Some after-market turbos and twin turbos will run out of the MAP reading range. Alternately, diesel tuning a variable vane turbocharger can be accomplished by commanding boost so that the vanes are always compared against a limiting table. The limiting tables are then raised or lowered to achieve desired boost which is checked by an analog gauge. Injection Timing
Injection timing is the black art of diesel tuning. Talk to five guys about timing and you will get five theories and a fist fight. The injection event in a diesel engine is defined by the amount of time that the injector is open and fuel is spraying into the chamber. The on-time (duration) can vary from zero to 80-plus degrees of crankshaft rotation. That is to say, the injector can be on for a long time while the piston is compressing the charge and also long into its power stroke. Our goal as tuners is to get the fuel into the combustion chamber so that it can react with the air while reaction conditions are most favorable. Reaction conditions are most favorable when the air in the cylinder is near top dead center (TDC) and is very hot. The rule is that as you add injector duration (fuel) you have to increase timing so that the injection event is more closely centered over TDC. Fuel system limitations (nozzle size and pressure) prevent ideal injection as RPM and fuel demand increase.
As we spray more and more fuel before TDC we begin to create a pressure spike in the combustion chamber that can lead to noisy engines and bent or broken parts. Never fear, the future holds promise on this front. Through use of an innovative chamber pressure monitoring system we have been able to see how timing and other variables directly relate to cylinder pressure. We are starting to quantify the limits. However, most users will not have access to these tools, so it is important to at least have a basic understanding of how timing changes affect diesel tuning.
Chamber pressure plot versus crank angle: 2850µs pulse-width @ 3,150 RPM with 27 degrees of timing results in peak pressure of 2,900psi. Total peak rod load of ~37,000 pounds.

Chamber pressure plot versus crank angle: 2850µs pulse-width @ 3,150 RPM with 27 degrees of timing results in peak pressure of 2,900psi. Total peak rod load of ~37,000 pounds.

Diesel Tuning 101

Luckily, you do not have to take a physical chemistry course to take away the important concepts. Here is an explanation that I have found helpful when trying to put all of these variables together in my head.
First, understand that the combustion process is essentially a chemical reaction happening in a cylinder where one ingredient, air, is having a second ingredient, fuel, added to it. While the fuel is being added via the injector, the size of the cylinder is shrinking and the heat is being added. Our goals with respect to setting timing are as follows:
Minimize noise, vibration and harshness. This is done by controlling the rate of combustion and the integral (amount) of combustion that takes place before top dead center. As the ratio of combustion before TDC: Ratio of combustion after TDC shift toward the compression stroke, peak cylinder pressure increases and engine gets noisier.
Achieve the lowest peak cylinder pressure/torque produced. This builds on #1 above: ideally we would have the charger release all of it is energy after TDC where it can positively affect the power stroke.
Achieve combustion when the reaction conditions are most favorable. We would like to start and end the injection event while the piston is near top dead center and reaction container is small, allowing a more thorough reaction and less soot production. As the piston travels away from TDC, the charge density lessens and combustion conditions become less favorable (less efficient). Notice that this can conflict with #1 and #2: as piston dwell time decreases, fuel needs increase.
Second, understand what variables we have control over:
Fuel rail pressure – This is the pressure with which the fuel comes out of the nozzle. As pressure increases, fuel flow rate increases. Be careful though, the two do not have a direct relationship. The fuel volume increases to the square root of the pressure. For example, when pressure increases from 4,000 PSI to 16,000 PSI, while the pressure increases fourfold, the fuel volume increase is only twofold. If we double the pressure, the fuel would increase about 1.4 times. Raising fuel pressure also increases fuel atomization, users may find this helpful at low speed for trucks with larger injectors. Proper atomization is crucial for complete diesel combustion. Increasing rail pressure effectively increases the amount of fuel delivered before top dead center, all else equal.
Boost – Our old friend is an important variable to consider. If the fuel curve of the tune is commanding more fuel than can be supported by the turbo (boost) then we can anticipate the fuel injected at the end of the stroke will not be used to create energy. This over-fueled condition will effectively tip the ratio of combustion before top dead center back toward the compression stroke. The result will be a rattle and laziness.
Pulse width- We control when the injector opens and closes by selecting injection timing and then selecting pulse-width. The duration in units of time never changes. However, when RPM increases, the window of opportunity to fuel the engine becomes smaller as dwell time decreases.
Third, understand the things we cannot directly control which may affect the combustion process.
Intake air temperature – As the truck is run down the track with the turbo screaming, the intercooler eventually becomes heat soaked and starts passing hot air on to the intake charge. Hot air in the cylinder means faster flame propagation and a quicker interval between start of injection and start of combustion. This is one that can sneak up and bite you in the butt by pushing peak cylinder pressure up through the course of a run or dyno pull. Pull timing via the IAT modifier table to combat this problem.
Cylinder heat – The intake charge will absorb heat from the cylinders and pistons of a hot engine. The effect is much the same as with intake air temperature. Take timing out via the engine coolant temp tables to help balance this.
Other fuels/oxidizers in the charge air – If you have added methanol, propane, or N2O to the intake stream then you have potentially altered the rate of combustion within the cylinder. Because variables are not injected with the fuel, but rather come premixed in the intake charge, they have the potential to raise peak cylinder pressure by releasing energy through combustion before top dead center.
Fourth, divide and Conquer! – Identify, based on scanning and logging, which base timing table your truck is running in and adjust it using the guide below.
Tune for cruise based on engine sound and responsiveness. Cylinder pressures at cruise are not going to damage parts easily. Add timing in two-degree increments until the rattle versus responsiveness trade-off does not balance for you. Timing at cruise affects fuel mileage slightly, but not nearly as much as a gas engine so don’t feel like you need to be really aggressive.
Tune for towing a load based on engine noise and EGT. If you are towing at what you believe to be a reasonable RPM, with turbo vane position between min/max (not at max), and fueling but the EGT are still creeping up, then it is time to add timing. A few degrees difference in timing while towing can make a 100-degree or more difference in EGT. Add timing until you hear the motor getting noisy or until rattle is noticeable upon throttle tip in.
Tune for WOT based on the boost curve and your tolerance for cylinder pressure. Before the turbo is lit, it can take advantage of low timing numbers to build EGT and improve spool up. The truck should not rattle under heavy acceleration. As the turbo spools, ramp in timing to take advantage of the increasing air mass and ensure the fuel is in the chamber during optimal reaction conditions. Peak timing over 25 degrees at RPM over 3000 RPM on stock injectors at full rail pressure can potentially shorten connecting rods and push head gaskets. Of course my numbers are open to interpretation and others will probably not agree, but based on cylinder pressure testing I have seen peak cylinder pressure increase dramatically as timing exceeds 24 degrees under these conditions (even worse at lower RPM). A good guideline is that running over 30 degrees of timing is not sustainable long term on a stock short-block.

Diagnostic Trouble Codes Realated to Diesel Tuning

Under normal operation, the engine controller will perform sanity checks on all of the component systems (turbo, fuel system, EGR, glow plugs, etc.) in order to make sure the vehicle is operating as the manufacturer intended. The factory calibration was written to meet a number of stringent governmental regulations on emissions. In order to make sure that the vehicle is emitting at levels similar to those reported under governmental tests, the engine has to achieve its commanded fueling, boost, EGR, and exhaust filtration settings. The majority of these diagnostic tests compare actual sensor inputs to expected values of those sensors over the course of operation. They can be found in the engine diagnostics folder of the calibration file. If a sensor is out of its acceptable range for a predetermined time, it will set a fault. A fault can have a number of consequences ranging from simply storing a code without setting an engine light to limiting engine output until the fault is resolved. As we adjust the engine systems to operate outside of their fault limits, we occasionally have to go back into the tune to adjust the diagnostic parameters. We can adjust the acceptable ranges on the sensors, the operating conditions to perform diagnostic checks, the time allowed before setting a fault and even the consequence of the fault. It is at the tuners discretion which adjustments he feels necessary, but be aware that sending a customer home with a freshly tuned truck only to set an engine code can be a rain cloud on an otherwise sunny day. Take test drives, warn the customer about the possibilities of fault codes and remember to scan for trouble codes as part of the diesel tuning process. Adjust as needed.
Diagnostic trouble code list and possible settings for various codes.

Diesel Tuning: Much More

There are a whole slew of other parameters in the software which can be used to control things like the rev limiters, idle speed, speed limiter, tire size, transmission operation and more. In short, if GM programmed it then we can change it to better suit our individual needs. Take time to learn, experiment in small steps and share your findings with others out there so that we may improve the hobby for everyone. Put safety first!
If you are interested in continuing your structured learning with EFILive on Duramax trucks, consider taking a class; or, use choose a tune from our library of pre-built tunes in order to kick start your adventure. See www.Duramaxtuner.com for more details.

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