Dynamic EFI

Bringing TBI and Multi Port Fuel Injection to a New Level.



Introduction to Tuning, Part 2

Preface:

This paper is an introduction to the basics of EFI tuning. It covers what changes to make and why. Although similar to the ODB1 GM systems there are some differences.

The EBL Flash system allows the user to easily make changes to the tune and try them out. Please see the first part of the Introduction to Tuning to become familiar with the use of a calibration editor and the use of the EBL Flash What's Up Display (WUD).

For stock engines and drive train there are 30-some calibrations provided with the EBL Flash, twelve with the EBL P4 and one with the EBL SFI-6 system. One of these will be a good starting point for your vehicle. Most likely no other changes will be required. Just flash it in and proceed with some VE Learns.

On the other hand, if the injectors are larger, the fuel pressure has been increased, heads or cam changed, then some of the calibration parameters will require changing prior to starting the engine. In this case select a base calibration that is close to the engine and transmission and modify it. You can also copy and paste from other provided calibrations to create a new starting calibration.

Then once an engine has been modified with better heads, cam, and exhaust, additional tuning will be required.

Note that if at all possible start your tuning with a stock engine. Then move on to making changes to the engine. This will allow you to gain experience in tuning before it becomes an absolute necessity.Which then makes it easier to deal with tuning a modified engine.


The First Changes:

To start out look through the EBL_F_BINs.txt file (on the CD which should be copied to your PC/laptop). This lists the current calibrations for the EBL Flash. Select one that closely matches your engine and transmission combination. Read the BIN into your calibration editor and immediately save it with a different filename. This will be your starter BIN (also known as a 'calibration').

Note that the EBL_Calibration.html file lists the tuning parameters. It is helpful to refer to it while reading through this introduction. This entries in the calibration document, the calibration editor, and this paper will match. In this paper the entry names will be double quoted.

Also, there are additional notes on setting up for VE Learns in the What'sUp.html document. Please refer to those prior to setting up a VE Learn. It isn't difficult, it is just that certain  items need to be under control for a good learn to take place.


Cylinder Count:

The first thing to check is the "Number Cylinders(6=192 8=0)" parameter. It must be correct for the spark timing to be correct. This is a set-it and forget-it parameter unless the engine is swapped for one with a different number of cylinders.


Base/Initial Spark Timing:

Note: on DIS equipped engines this section partially applies. The initial timing  of the DIS system usually can't be changed. Just make sure that the "SA - Initial SA" value is set correctly. For a 6-cylinder GM engine it is 70* BTDC.

Check/set the "SA - Initial SA" value in the calibration (BIN file). This value must match the actual distributor base timing. The ECM needs to know the base distributor timing so that it can properly program the distributor for the commanded timing value. So if the distributor base is at 0* BTDC, set this value to 0*. If the distributor base is at 4* or 6*, then set this parameter to match at 4* or 6*.

A typical base timing setting is between 0* and 10* BTDC.

Note: the base distributor timing is set with a timing light on a warm engine with the EST/BYPASS connector open.

The distributor base timing is used during cranking. It may be changed to suit the engine. If the engine windmills on cold cranking then a higher base & matching initial setting can be used. If the engine hard cranks hot, then a lower base & matching initial setting can be used. Typically, an engine with more cam overlap requires a greater base & initial timing setting for a good start up.


Injector Flow Rate and Engine Displacement:

This will need to be changed for any change in engine displacement, change in fuel pressure, or a change in injector flow rate.

The EBL P4 and EBL SFI-6 Flash use separate engine displacement and injector flow constants:
The EBL Flash uses a value called the Base Pulse Constant (BPC) to define the injector flow rate and engine displacement. It is the two of them rolled together into a single value. There are two tables that need to be filled in with the BPC value(s):
To calculate the BPC value(s) there is the EBL_Utility Windows program. Earlier releases of the EBL were supplied with spread sheets for the same purpose. In the EBL_Utility or spread sheet fill in the values for engine displacement, number of cylinders, fuel pressure and so on. The BPC tables values are shown on the screen.

The BPC values, which are shown in red, can then be copy & pasted directly into the calibration editor.

Note: it may be required to change the AE MAP & TPS PW tables. See the Acceleration Enrichment section for more information.


Spark Advance:

The main and extended SA tables may or may not need to be changed. The main influence on SA is the head material and the chamber design (shape & size). Other considerations are the vehicle weight, chamber temperature (air intake and manifold also affect this), induction design, fuel octane, compression ratio, and gearing.

If the heads on the engine match the base calibration you started with, then for now leave the SA tables alone.

However, if  as an example you installed Vortec heads on your L05 engine. Pick an L05 calibration that matches your vehicle along with the transmission type. Then in your calibration editor copy over the main & extended SA tables from the EBL_F_1000.bin calibration. The _1000.bin calibration has Vortec SA tables:
If running a non-swirl port iron head then the base LG4 calibration SA tables should be used ('416 heads, EBL_F_TB.bin).

There are also a couple of calibrations for aluminum headed engines. Although both are for the Corvette '113 heads, one is for a TBI single plane manifold and the other is for the TPI system..


Volumetric Efficiency (VE):

If the engine is basically stock, or at the most a mild cam it is best to leave these alone. The VE Learning of the WUD will take care of the VE tables.

If you are setting up a fire breathing dragon of an engine then these tables should be adjusted. In general a lower VE at lower RPM ranges and higher VE in the upper RPM range. At the same time experience in tuning these types of engines is required. You may need to rough in the lower VE areas several times as you work on getting the engine to run. Then move on to doing VE Learns.


Engine RPM Limiting:

There are two functions provided in the EBL to limit the engine RPM. One reduces the SA to cause a loss of power. The other turns off the injectors (fuel cut) to shut off the engine.

The purpose of the spark reduction feature is to keep the driver from over-revving the engine. It causes a loss of power that the driver can feel and alerts them to the fact that they need to up shift. It should be set slightly above the desired shift RPM.

The purpose of the fuel cut RPM limiter is to protect the engine if there is a sudden loss of traction or drive line breakage. So it should be set high enough that it is not hit even with spirited driving.

Note about the high RPM fuel cut limiter: if using any type of auxiliary fuel unit set these to a high value (10,000 RPM). This includes an alky set up, aux injectors, and so on. The reason is that cutting the main injectors off while still supplying fuel by another means will lean out the engine, not shut it off. This in turn can cause melted parts, which is bad.

These limiter RPM values have separate entries in the calibration editor dependent upon the engine cylinder count. There are also valet mode parameters, so be sure to set the right ones.

Vehicle MPH Limiting:


Just as the RPM limiter there is vehicle speed limiting. It too uses a SA reduction and a fuel cut. They are set to 170/168 MPH in the supplied calibrations. So if going for a land speed record set them to 255 MPH to disable the MPH limiters.

Idle Speed:


If the engine is cammed then the idle speeds most likely need to be increased. There are two tables for this: one for in park/neutral (auto only) and another for in drive (stick & auto).
The easiest method of increasing the idle speed is to highlight all entries and add an offset. Use the same offset for each table. This retains the higher idle speeds for a cold engine along with the higher idle speed when in prk/neut.


INJ - MPG Injector Flow Constant:


The WUD uses this value for the trip display calculations. Set it close to the required value. Then as the tune comes together do some actual testing and make minor corrections. Even if this isn't done, it may still be used as a relative value to gauge tuning for increased fuel mileage.


AirFlow - Displacement Scalar:

Last but not least, the "AirFlow - Displacement Scalar" value. Note that this value is not critical. I mention it here as later once tuning has been started the tuner finds it and gets worried about it. So set it now and forget about it. Also note that it tops out at about 487 CI. As mentioned, it is not critical. So if running a 502CI engine, just set it for 487 and forget about it.

If your tune if nearly complete and you find the airflow scalar way off, just leave it.


Now That We Have a Starter Calibration:

Working With the New Calibration:

Now it is time to flash in the calibration and start the engine. Be sure to save the BIN (ALT-F, S) prior to flashing it.

Start a data log in the WUD, then start the engine. You may need to use some pedal to get it started or to keep it running. It all depends upon how close the tune is. If it running OK then let it warm up and go into closed loop. Can now observe the BLM value to see how far off the fueling is.

At this point you need to decide whether to go with the VE tables as is and let the VE Learning take care of them. Or make some adjustments to the VE tables and flash in the updated calibration. Same if the engine doesn't want to run. If it is chugging and blowing black smoke, then it is too rich. If it surges in RPM then dies, it is too lean.

Increasing the VE table values will make the engine richer, and vice-versa a lower VE value will lean the engine. If you are not sure of what area of the VE table to change look at the log file in the WUD Analysis display.

Note: at this point shut off the engine, wait 10 seconds, then restart it. This does an IAC reset and sync's it with the ECM.

Continue to make further tweaks to the VE table (Low Speed) until the engine runs OK. You should be able to get it to idle and rev (go easy here, keep the RPM reasonable) without issues. Can use the VE Learn feature of the WUD during this time.


Mechanicals:

At this point there is something that needs to be mentioned. This is the mechanical set up of the engine. Fuel pressure, fuel delivery, valve adjustment, distributor base setting. These and other odds and ends will affect the tuning process. The first sign that there is fuel delivery issues is that the tune goes in circles. Other issues that crop up is excessive knocking, no power, can't set the fuel pressure low enough. Wrong spark plugs, incorrect firing order (wires on the wrong plugs), distributor moving (hold down bolt not tight enough).

The reason to mention this is to keep in mind that the tune is only as good as the mechanical set up of the engine. If the tune doesn't keep moving in a forward direction, if the power seems low, if you feel as though you are going in circles, then it can pay off to check other items.


Test Drive:


The first drive should be done in a low to no traffic area. A long driveway is good. Otherwise go out at a time when the traffic is light. Take it easy, make sure to start a VE Learn and to data log, then drive around for about 10 minutes (with the engine warmed up).

Dependent upon how close the tune is the engine may or may not have run OK. There is a good possibility that it stuttered, sputtered, surged, or chugged at times. This is why the initial drives should be done in light to no traffic.

Take a look at the WUD VE Learn display (corrections screen). Big corrections? Stop the VE Learn and flash in the new calibration. Then set up another VE Learn, data log, and take the vehicle for another drive.

Drive for another 10 minutes, stop and check the VE Learn corrections display. Same as before, stop the VE Learn and flash in the new calibration. Each time you do this the engine will be running better.

As you continue to do VE Learns go to a higher engine RPM. To do this hold the gear longer before up shifting. Try to get as much coverage over the load and RPM range as possible. You can also increase the length of time driving before stopping the VE Learn and flashing in the new calibration.

Tips for good VE Learns:

Further Tuning:

As the VE tables take shape the low RPM and low MAP area may need to be manually changed. What can happen is that this area ends up higher in value then the surrounding area. This is due to a VE Learn not able to take place there. In this case just flatten out the lower RPM/MAP triangle of the low speed VE table.

Can do this by dragging the graph of the VE table or using the fill feature directly on the table. This is a before look at a VE table with a cam'd engine:

VE Before

Then after the non-learn area has been flattened:

VE After

On the other hand the low RPM and high MAP area is used during cranking. So don't get carried away and reduce the whole low RPM area.

With the engine running better you can start looking into other items. This includes but not limited to spark knock, idle speed, surging during decel or idle, torque converter lockup or TH400 kick down, acceleration enrichment (AE) and WOT power.

Much of the required tuning will depend upon how the engine runs and the vehicle drives. Along with how modified the engine is from stock. At this point if the engine has bolt ons with a moderately increased injector flow rate it will probably run rather decent.

If the engine is more heavily modified: heads, cam, intake, larger injectors, then further tuning is likely to be required.

One aspect of the ECM software is known as a delta. You will read/hear of delta TPS, delta RPM, or delta MAP. These are sometimes abbreviated with a small 'd' and then the annunciator. Such as dTPS, dRPM, and so on. So what is a delta value?

It is defined as the change in value over time. The ECM software runs in time scheduled loops, it is not free running. So it can keep a value in memory until the loop runs again and know the time difference between the old value and the new (current) value. If the old value is 98 and the new value is 110, then the delta value is 12 (110 - 98). Deltas may be in the positive or negative direction. Such as an opening throttle vs. a closing throttle (dTPS). If the loop is run every 100 milli-seconds, then the old value is a 100 milli-second delayed value. So the delta is over a 100 milli-second time period.

The other method of creating delta values is by the use of a filter. By using a programmable filter value (coefficient) the tuner can change how much delta there is. A filter lags the change in a value based on both time and the value of the filter. The acceleration enrichment (AE) parameters have a table of filter values to create a dTPS and a dMAP value. By using a smaller filter value the delta's are increased. For AE this increases both the volume of AE fuel and the duration of AE fuel (more on this later).


Spark Advance:

The maximum spark advance an engine can use is defined by either the detonation limit or the timing limit of the heads. Defined by detonation is easy, the engine knocks and can either back off the timing or run a higher octane fuel. The detonation will stop.

The timing limit of heads is a little more difficult to discover. This can be seen as the engine (many times) won't go into detonation. Keep throwing more spark timing at it and it will not detonate.

What does happen is that the power drops off and the engine gets rough. The power drop off can be discovered on either a dyno or a track.

The roughness of the engine is something that the tuner needs to pay attention too.

Note that a rough engine feels fast, but it is slow. A smooth engine is fast, but it doesn't feel fast. Use the data logs or a track to check the vehicle rate of acceleration.

There are other aspects for tuning spark timing that should be considered. Spark advance is a way of controlling the engine torque. More advance, more torque. Less advance, less torque. This can be used to advantage.

For a stick driven vehicle to much timing in the low RPM range can make the throttle jumpy. Adjust accordingly for best driveability.

Vehicles can use more WOT spark timing is the lower gears. As the transmission is up shifted the air drag from the vehicle speed increases and the engine acceleration slows. This requires less spark timing. For stick vehicles the PE spark timing can be set according to which gear is in use.

There is launch mode (LM) spark advance specifically for automatic equipped vehicles. Use the additional timing to quickly bring the engine up against the torque converter. This provides better performance and lower fuel consumption. This LM advance can also be used for stick vehicles. It allows for more timing on take off then would be used once a vehicle is up to speed.

During WOT operation heat is also building in the engine. Again, less timing is required. Note that the EBL has a PE AFR enrichment over time to aid in cooling the engine.

A quick mention of two additional spark reduction tables: the TCC locked retard table and the boost spark retard table.

As the TCC locks it places an additional load on the engine. By using the TCC locked retard the main SA table can retain enough SA for decent performance with an un-locked TCC. Then once the TCC locks the tuner can reduce the spark timing by the proper amount to reduce detonate or roughness in the engine. A win-win with this one.

The boost retard is used to reduce the spark timing as the RPM and boost changes. Having this functionality in the EBL eliminates the need for add on boost retard units.


Deceleration:

At times deceleration can be troublesome. If too lean the engine can start to surge. As the vehicle slows to a stop this surging can carry into idle mode. Which can result in the engine stalling. Best bet here is to manually increase the VE in the low MAP areas of the RPM being used. This is usually in the idle to low RPM range of the engine.

You can un-check the forced open loop during decel option to do a VE Learn. However, since prop gains will then be active and the AFR will get leaned out some. It is easy to get surging during decel. This surging is why the decel is open loop in the provided calibrations.

Another issue is that during decel the PW gets small. Very little fuel is required. So it is easy for closed loop INT/BLM to rise and fall while being unable to control the actual AFR. This time it will start to buck as the fuel comes in and out.

Increasing the injector compensation offset will help in this regard. Which is required for proper control of the injectors. But it doesn't always correct the surging.

An aspect of decel is that the air/fuel density in the chamber is very low. Which is difficult to light off. So a little extra fuel goes a long way in preventing misfires. And it isn't really a lot of fuel.

This extra fuel also helps when the engine drops into idle. Otherwise idle can start to surge before either settling down or stalling (it's usually one or the other).


Acceleration Enrichment:

The purpose of acceleration enrichment (AE) is to add fuel whenever the throttle is opened or manifold pressure increases. The affect is to prevent sags, lean backfires, and popping out of the throttle body. In the carburetor world AE is known as pump shot.

The reason AE is required is that as the manifold pressure increases fuel drops out of suspension and coats the walls of the intake manifold and runners. The additional AE fuel makes-up for this loss to the manifold/runners. Both TBI and MPFI systems require AE. With the TBI system requiring higher levels, and MPFI being a little tricker to get correct. The wet flow plenum on a TBI system buffers fueling changes. This helps prevent rich & lean spikes by smoothing fuel delivery to the chambers.

The higher the airflow velocity, the less fuel will be on the walls. And, the less fuel will drop out of suspension with an opening throttle.


For tuning AE there are a number of tables that can be used. There is both delta MAP and delta TPS tables that control the volume and duration of additional fuel. This added fuel is further changed by an RPM and CTS based tables.

Before AE is added there are a couple of qualifiers. The TPS needs to have increased more then a set amount for dTPS AE. And the MAP needs to have increased by a set amount for dMAP AE. These are programmable parameters:
Note that the dMAP & dTPS AE  functions are separate from each other. IOW, it is possible to have MAP AE and not TPS AE.

Chain of events:

Once one or both of the thresholds have been exceeded the ECM will calculate the AE fuel pulse width. The delta of the MAP/TPS will be used to look up the PW value from the respective AE PW table:
The results of these two lookups are added together. Then compensated for by the engine RPM:
Then further compensated for by the engine coolant temperature:
Both of these compensations can increase or decrease the volume of AE fuel. At higher engine RPM very little AE is required. The airflow through the induction system is high enough to prevent the fuel from falling out of suspension.

A cold engine requires additional AE fuel. So it is common to add to the CTS compensation as the engine CTS falls.

The final AE fuel is then added to the engine.

The MAP and TPS Filter Tables:

There is two tables of filter values based on the engine coolant temperature. One table for MAP AE and another table for TPS AE.
The purpose of the filter tables is to create the delta MAP and delta TPS values. The smaller the filter value the larger the delta. This is important to understand as it affects three areas of AE.

Remember that the smaller the filter value in the table the sooner, larger, and longer lasting the delta MAP/TPS value will be.


The dMAP and dTPS values are used to check the threshold to see if AE is required. And is used to lookup the AE PW from the PW tables ("AE - MAP PW" & "AE - TPS PW").

A lower filter value also increases the duration of the AE. It takes longer for the delta MAP/TPS to return to zero once the current MAP/TPS stops changing.

In the end the filter values affect three areas of the AE functionality: the threshold for AE, the volume of AE, and the duration of the AE.

Affect on AE of Changing Injector Flow Rate:

Changing the injector flow rate directly affects the volume of AE fuel. This is because AE is pulse width based and is not affected by the BPC value.

The best way to compensate for a change in injector flow is to use the ratio of the old injector flow divided by the injector new flow rate. Using that ratio compensate the two AE PW tables (MAP & TPS). As an example, say that the 61 #/hr injectors are replaced with 80.5 #/hr injectors at 18 psi. The new flow rate is then 94.7 #/hr.Creating the ratio:

 61 / 94.7 = 0.64

Go into your calibration editor and open the two AE PW tables. Multiply each entry by 0.64 (toolbox!).  Save tables, save calibration (BIN). Done.

IAC Opening AE PW:

Under the AE parameters is an "AE - IAC Opening Fuel" term. For TBI systems as the IAC opens (retracts, more steps), fuel needs to be added. That is the purpose of the IAC Opening fuel parameter. It adds a small amount of fuel each time it steps open some.

Note that MPFI engines typically do not require IAC opening fuel. And the PW is set to 0.

AE Variables in the Data Log:

The What's Up Display Analysis screen Dump Log output of the data log contains five columns of AE information. This data is helpful in knowing what the delta values are along with how much AE is being added to the engine. Here is a short snap shot of an AE event along with some additional useful columns.

Some of the columns are:

sPW    injector PW, sync
dTPS   delta TPS%
tpsAE  TPS PW in milli-seconds from the TPS PW table
dMAP   delta MAP in KPa
mapAE  MAP PW in milli-seconds from the MAP PW table
aePW   final AE PW after CTS & RPM compensation

Note that the values don't always 'look' correct. This is because the ECM is recalculating the AE 80 times a second. While we are data logging at 17 times a second. However, they do give a decent picture of how much and from where (TPS or MAP) the AE is being contributed.

RUNTIME   RPM MPH MAP TPS  sPW  dTPS  tpsAE dMAP  mapAE   aePW

00:00:44 1750  22  33   2 1.160  0.0  0.000  0.0  0.000  0.000
00:00:44 1700  22  34   3 1.709  0.8  0.137  0.0  0.000  0.458
00:00:44 1650  22  37   5 1.678  1.2  0.107  2.8  0.000  0.275
00:00:44 1650  22  38   5 1.770  0.4  0.107  4.4  0.000  0.458
00:00:44 1650  22  40   7 1.923  1.2  0.107  5.3  0.000  0.732
00:00:44 1675  22  43   7 2.350  0.8  0.107  6.6  0.076  1.083
00:00:44 1650  22  45   8 2.289  0.8  0.076  8.8  0.092  0.626
00:00:44 1700  22  47   9 2.808  1.6  0.122  8.4  0.092  0.732
00:00:44 1650  22  48   9 2.380  0.8  0.107 10.9  0.092  0.626
00:00:44 1625  22  51  10 2.899  0.8  0.107 11.3  0.107  1.190
00:00:44 1650  22  54  11 2.838  1.2  0.122 11.3  0.107  0.916
00:00:44 1675  22  57  14 3.204  2.0  0.153 15.0  0.137  1.419
00:00:44 1700  22  62  15 3.235  1.2  0.107 16.6  0.137  0.793
00:00:44 1675  21  64  15 3.082  0.4  0.076 18.4  0.122  0.458
00:00:44 1675  22  65  15 2.899  0.4  0.000 16.3  0.137  0.504
00:00:44 1675  22  65  15 2.838  0.4  0.000 13.4  0.122  0.397
00:00:44 1725  22  65  15 2.777  0.4  0.000 13.8  0.107  0.397


Injector Compensations:

The purpose of injector compensation is to make up for the time it takes for an injector to open and then close. The proper values can be difficult to obtain, so many times they are guessed at based on results. Which in many cases works out OK.

In general terms the higher the fuel pressure the longer it takes for an injector to open. Increased fuel pressures are more prevalent on TBI systems. And as such should have the injector compensation values increased. Check the 5.4l calibration with the 80# injectors at 22 psi. Compare those values with some stock calibrations. That will give an idea of what values can be used.

With port injectors there is some information available for various injectors. If available then it is worth using to update the calibration.


Decel Fuel Cut Off:

Not much to say about decel fuel cut off (DFCO). It is intended as catalytic converter protection during long decelerations from speed. The ECM does this by shutting the injectors off which cuts off the supply of fuel to the engine. Once below a programmable MPH or RPM, or the driver puts their foot back on the gas pedal DFCO is exited and the injectors are re-enabled.

Just don't set the RPM or MPH limit too low as this will cause engine stalling (not fun).

On stick vehicles with modified engines DFCO can be rather harsh. In these cases you may need to disable it by setting the enable DFCO enable temperature threshold high ("DFCO - Enable Temperature").


Torque Converter Lockup:

The torque converter clutch (TCC) is a mechanism that mechanically locks the engine to the transmission. It is contained within the torque converter. Only used with automatic transmissions, and is not a requirement. Some automatic transmissions do not use a TCC.

The primary purpose of the TCC is to increase fuel mileage and reduce transmission temperatures. A secondary benefit is that the torque converter stall speed may be raised without excess slippage while cruising with the TCC locked.

If using a 4-speed auto (200-4R, 700R4) the first item to check is whether the high gear switch setting is correct. Easy to do, take a short drive with the transmission gear selection in D (not OD) and data log. Then observe the data log on play back and check that the gear indicator is D. If it shows OD, then change the high gear switch selection in the calibration:

  "Option Word 2 - Bit 5 - HiGrH", if checked, then un-check, and vice-versa. 

This will ensure that the proper low gear or high gear tables will be used at the proper time. GM used both types of high gear switches and this is the easiest method to find out which one is in the transmission.

The following is a brief description of the TCC calibration parameters.

Relock delays: these are delays that take place after the TCC unlocks before it is allowed to re-lock.

Forced lock MPH: once over this speed the TCC will be locked. No amount of TPS% will unlock it.

Coast unlock: these are used to unlock the TCC while coasting with the foot off or nearly off the gas pedal. The min/max is used to prevent TCC lock/unlock chatter from having a single point threshold. Be sure to have some amount of difference between the values. There are a pair of min/max coast release values each for drive and overdrive.

MPH thresholds to allow lockup: the vehicle speed needs to be above these thresholds to allow the TCC to lock. Again, min/max values to prevent lock/unlock chatter. There are a pair of min/max MPH threshold values each for drive and overdrive.

Lock/Unlock vs TPS% and MPH: these are the key tables to controlling the TCC. Two tables each for a pair, then a pair each for in drive and in overdrive. These tables define how much throttle is required to unlock and to re-lock the TCC at various vehicle speeds (MPH).

The table " TCC - LoGr TPS% to Unlock" is used to define when the TCC is unlocked. Once the throttle position vs MPH is above the threshold the ECM will unlock the TCC.

The table " TCC - LoGr TPS% to Stay Unlocked" is used to define when the TCC is free to lock back up. When unlocked, the TCC will re-lock once the throttle position falls below the table threshold.

As an example, say you are driving along at a steady 55 MPH with the TCC locked. As the throttle is depressed to accelerate both the TPS% and MPH increase. Once the TPS% is greater then the value in the "TPS% to Unlock" table, the ECM will unlock the TCC.

Then once you reach 65 MPH (the desired speed), you back off the throttle to go to a steady cruise. Once the TPS% is below the value in the "TPS% to Stay Unlocked" table, the ECM will relock the TCC.


TH400 Kick down:

The EBL will control the electric kick down of a TH400 transmission. Note that the kick down solenoid in the transmission needs to be activated by a relay. The relay is activated by the EBL ECM.

Several of the included calibrations are set up for a TH400 kick down. It uses the TCC tables for this purpose. If you want to set up a calibration specifically then copy all of the TCC related parameters from a supplied TH400 calibration. Then set up the following option flags as shown:
The kick down and re-up-shift is controlled by the min/max TPS% coast unlock parameters. Set both the low gear and high gear parameters the same. While setting the minimum value slightly lower then the maximum value.

Conclusion:

The information on this page is intended to get a tuner started on what changes are required. Getting started and getting the tune worked out can be tricky. However, in the end it all comes down to one question: how does it run? That is the single most important question for the entire tune. When the engine runs well, is tractable and driveable, delivers decent fuel mileage and power, then the tune is good.



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