NOTE: Please ensure you have one of these daughter boards inside your ECU before continuing. If you have a black microprocessor, then you have an MS1 and these manuals are NOT for MS1 see here for MS1-Extra Manuals

Warning for E-Bay buyers!! Please see the Official Suppliers list before buying through E-Bay. This is there for your protection.

Getting the Engine Started -- Setting the PWM for injectors -- Setting the Cold Start and Warmup enrichments -- Idle Control

Tuning the VE table -- Rescaling the VE Table -- Tuning the AFR Table -- Tuning Issues -- Resets

Tuning for Economy -- Tuning for Emission -- Spark Map Tuning

Acceleration Enrichments -- EAE Acceleration Enrichment Tuning -- MLV Log Viewing and Tuning Software

Before starting, make sure to:

Tuning the VE Table

The VE Table in MS2-Extra has the option to use a 16x16 or a 12x12 VE table. Select which table size you wish to use in "Basic Setup - General, lags"

Before starting to tune the VE Table it is recommended that you turn the Acceleration Enrichment (AE) off so you can see whats happening to the mixture as a direct result of the table rather than having fuel added from Acel Enrichment. To do this set the thresholds to 30V/S or 5000KPa/S see HERE for more details on AE. You may find that you’ll need to be light on the throttle as the AE is needed to fill 'holes' that occur when the throttle opens quickly. Remember to tune the AE when you have a tuned VE Table.

Another item to turn off during tuning is the Overrun settings as the PW may drop to 0.0mS causing lean spots. See HERE for more details

Tuning the VE table involves richening (by increasing the VE) or leaning (be decreasing VE) at each point in the VE table. Most of your driving will occur in a diagonal strip of the VE table, from low rpm, low kPa (i.e. idle) to high rpm, high kPa (i.e. WOT). You can adjust these values using the O₂ sensor, data logs and MSTweak, and/or the seat of your pants. Low rpm and low kPa (say less than half of the max rpm and max kPa) might be able to use stoichiometric or leaner. Richer mixtures would be used at high rpm and high kPa.

However, the low rpm/high kPa and high rpm/low kPa are not seen as often driving your vehicle. Basically, if the engine never runs in certain parts of the MAP, then the numbers there should not matter. However, since you may not be able to guess where you will run under every possible set of conditions, you put estimated VE numbers that make sense into the little used areas.

From this frequently used diagonal strip of the VE table, you will be able to see how much the VE rises from one rpm bin to the next, and use these differences to estimate the low rpm, very high kPa numbers and the high rpm, very low kPa numbers. Since you rarely (if ever) run in these parts of the table, the actual numbers will not make much difference, but they will be there "just in case". You are looking to create a smooth VE map wherever possible.

To set the VE table entries near idle, you should try to achieve the lowest MAP (in kPa) that you possibly can, at your chosen idle speed. This will give the highest idle vacuum and the most efficient idle. Don't try to get to a target idle mixture (stoichiometric, or some other number), instead adjust the VE table entries around your idle rpm and kPa to achieve the lowest MAP reading as seen in MegaTune. As you work to lower the MAP, the rpm will likely rise, and you'll have to reset the throttle stop to lower the rpm to your desired idle speed. When you have it set so that either raising or lowering the VE table entries increases the MAP, then you have the best idle mixture for your engine (it will require the smallest throttle opening).

To alter the VE table values using MegaTune, go into Tuning - VE Table 1. Here you will see a green ball floating around the 3D map, this is the current area of the map that the engine is running in. Use the arrow keys on your keyboard to take the red cross hatch to the area of the green ball. You will find that the green ball will probably end up between the cross hatches as below, that means youll need to alter the 4 areas around it to tune that area, as shown. Adjust them all by the same amount by pressing "W" to weaken (reduces the VE table value at that point by 1) or "Q" to Richen (adds 1 to that VE value), simply go to all 4 points and press W or Q once or twice and see what the reaction is on the O2 meter. Press "F1" for more help on this screen.

The 4 points to alter when between cells.

Once the engine idles smoothly, keeping in the Tuning VE Table screen, go to File - BURN TO ECU (or Alt and B) this will ensure the settings are kept in the ECU or the settings will be lost once the power is turned off.

Setting the KPa values in the Table

Note that the scale in MS2-Extra is in %, so 100% = atmosphere (100KPa) in MAP mode, or 100% TPS in Alpha-N, etc.
So obviously a boosted engine will go over 100%.

It is a good idea to set either the second or third row of KPa bins in the VE Table to the idle MAP value. So, for example, if you idle at 35KPa set the first to say 20KPa or even a little lower (this can be used for fuel saving during over run, the second can then either be 35KPa or a value between 20 and 35 then the next could be 35. The reason is it is always easier to tune idle if the point of idle is on a cross hatch, then theres only really 2 points that influence it rather than 4, this may not be possible with a varying idle map, but its worth trying if you can.
The rest of the KPa values will depend on where your engine cruises and what boost pressure you run, remember 1PSI of boost is aproximately 7KPa (6.8), so for 8psi of boost your max KPa value will be 8psi x 7KPa = 56KPa above atmosphere, so 100KPa (atmosphere) + 56KPa of boost = 156KPa (round that off too 160KPa)
Lets take a NA engine into concideration; Idle is 30KPa and cruise is also around 30-50KPa. At cruising KPa there will need to be more rows than at any other to get the engine to maintain a nice smooth AFR through out that area. In a race engine this section wont matter so that rule doesn't apply. Wide open throttle on a NA will be 100KPa (depending on where you live but 100KPa should be fine) I would set this engine up like this:

KPa Scale for VE Table

Setting the RPM values in the Table
It is a good idea to set the first RPM row so it is lower than idle, this allows you to set a richer area than at idle so if the engine starts to stall or slow then it picks up a little when it goes to the richer area. So, for example, if you idle at 800RPM then set the first row to 500 and the next to 700. The 700 RPM row will be the one that tunes the idle AFR, if it drops below 700 it will be richened by the 500RPM row, but only if it drops below 700, which is 100 below your idle speed. The next few rows should be around your cruiseing area, this again, allows for better tuning of the AFR at cruise allowing a smoother, more efficient drive and a better ride around town where slow engine speeds are necassary.

Setting the TPS values in the Table for Alpha_N setup
If running Alpha_N you will need lots of bins set around your cruising area and a few around the idle (foot off the throttle). The next few values should be very close to each other up to around 25% opening as this is the area that will need more tuning at low RPM. One thing you have to always remember with alpha-N is that you don't actually know where the effective WOT is anymore (i.e., when you have enough throttle that opening it further doesn't affect the amount of air being ingested). At low RPM WOT could be only 20% throttle. It is worth setting 5-8 of the total TPS bins (load on the VE Table) to cover the first 20% - 30% of the throttle opening to make tuning easier. This will help you end up with a driveable car, as most driving on the road is done in the first 30% of the throttle. The rest of the bins can fill in the gaps between 30% and WOT. (Wide Open Throttle).

TPS Scale for VE Table

At non idle areas of the VE table, you will generally run lean (low loads and speeds) or rich (high loads and speeds). High loads are associated with high kPa MAP values. Deciding exactly when (and how much) you should run rich is mostly a "seat of the pants" thing. When tuning, you will find the engine will surge (at low loads) and "coughs" at higher loads if it is run lean. Adjust the VE at the point where this happens so the this does not occur. Check the plugs for detonation (tiny black and white flecks) when tuning at high loads and rpms if you suspect detonation at all. A narrow band should read at least 0.8 volts under full throttle, at least for a starting point in tuning WOT. There are more details later in this section.

If you get the injector opening time correct, and the REQ_FUEL accurately represents the flow rate of your injectors, then the VE entries will be close to the VE*gamma. However, if your opening time is not right, or your REQ_FUEL is not, then the numbers will be skewed by the percentage the values are in error. In general, except for when you are first trying to get your engine started, use the calculated value for REQ_FUEL and do not change it.

Tuning the AFR Table

Air/Fuel Ratio (AFR) entries in the 12×12 MS2-Extra AFR table are expressed as a ratio of air to fuel by volume (for example 14.7:1 represents a chemically correct ("stoichiometric") ratio for gasoline. A ratio of ~16.5:1 gives good fuel economy at low engine speeds and loads, while a ratio of ~12.5:1 gives maximum power at high loads and rpms. These entries are used only to adjust the oxygen sensor target voltage, and only if you have a wide band sensor.

MS2-Extra uses one or two 12×12 Air Fuel Ratio (AFR) tables for tuning. MS2-Extra uses the AFR table in different ways, depending on the EGO feedback option you have selected:

• If you don't have an oxygen sensor installed, choose 'Disabled' under EGO Sensor Type in MegaTune, and MS2-Extra does not use the numbers in the AFR table to adjust the VE table numbers (as shown above) when calculating the pulse widths. There is no feedback.

• If you have enabled a narrow band oxygen sensor, choose 'Narrow band' under EGO Sensor Type in MegaTune, and MegaSquirt-II will try to adjust the amount if fuel injected, up to the limits you specify, to give the oxygen sensor voltage specified in the tuning software. The AFR table is not used, instead a single VOLTOXTarget is used.

• If you have a wide band oxygen sensor & controller, choose 'Single Wide band' under Settings/EGO Control in MegaTune, and be SURE to go to Tools/Calibrate AFR Table and select your controller type. Then MegaSquirt-II will adjust the amount of fuel injected based on the AFR table until the wide band controller reports a voltage corresponding to the air/fuel ratio in the appropriate cell of the AFR table.

  IMPORTANT NOTE: Do NOT burn tables ('Calibrate AFR Table' or 'Calibrate Thermistor Tables') on a running engine. Even idle is NOT allowed, because these tables ONLY exist in flash, so once a table is erased, there is nothing but garbage in there until it is re-programmed, one word at a time. Until that reprogramming is complete, operating the engine is unsafe.

Note the EGO feedback does not operate if any of the following are true:

These are set in the 'Settings/EGO Control' dialog. In particular, unless your 'Active Below MAP' is higher than your baro reading, you will not generate EGO feedback on the stimulator without applying a vacuum to the MAP sensor.

If you do not have a wide band sensor installed, you can calculated the VE value required to produce any other AFR:

For example, if you have a stoichiometric mixture (NB02 = 0.50 volts) with 65% VE at a certain RPM and kPa, then to lean the mix to 16.0:1 you need:

To richen an 80% VE entry to 12.5:1 from stoichiometric:

However, you cannot use the narrow band signal to determine a stoichiometric ratio at high engine speeds and loads - this will damaged your engine if you try! A wide band sensor and controller can be used under these conditions for feedback control.

With wide band sensors, simply set the desired AFR (and type), and adjust the VE table to minimize the EGO correction at all engine speeds and loads.

With a narrow band sensor, you have more work to do. Have someone ride with you and bring up the tuning page. See where the dot hangs around when you are under moderate load - this is where you need to focus on tuning. Later you will try to estimate the higher load numbers from those you determine under lesser loads.

Use the up-arrow + shift to richen the VE values - enrich (with increased VE number) the four corners around where the dot is - give each corner five up-arrow-shifts, and see if this helps. Be sure to turn on EGO correction, and then tune using the EGO correction gauge rather than the EGO voltage gauge. If correction is below 100%, then raise VE to raise correction and so on.

You can also datalog the engine parameters (including O2 volts) and inspect the resulting file to see where the VE needs to be raised or lowered according to the MAP, rpm, and AFR (if you have a wideband O2 sensor).

Here is a table showing you what AFR to run within your engines working range. Note that the engine rpm range is from 600 rpm to 6000 rpm, and the MAP values range from 15 to 100 kPa (telling us that this is a naturally aspirated engine). Beyond these values, MegaSquirt will use the last value from the “edge” of the table. (It does not “shut down” by substituting zero values.) In theory, at stoichiometric mixtures, the values at 100kPa would reflect the torque curve of the engine at WOT, assuming a constant AFR level.

Having an O₂ sensor makes the driving part of the setting up much easier, as you can datalog and use MegaLogViewer to get the VE table set up with a few easy drives up and down the street, a bit more tuning, and you are ready to go a bit harder. You do not go harder if there are any problems [typically a back fire means too lean, sluggish revving means too [rich]. Read the “Datalog” section for more information.

Have someone ride with you and bring up the VE table1 tuning page. Drive at a sensible speed and start with low rpm and low KPa areas (crusing, etc) See where the " Green dot" hangs around when you are under load - this is where you need to focus on tuning. Use the Q and W keys to richen / weaken the VE values - enrich (with increased VE number) the four corners around where the dot is - give each corner (section) two to five Q button presses (W for weakening) , and see if this helps. Turn off the O₂ closed-loop mode by setting the step size to zero in Exhaust Gas Settings. Watch the Air:Fuel gauge on the tuning page and use this as feedback for rich and lean. The AFR (02) gauge may move too fast from rich to lean to be able to tune. Another strategy that works is to turn on EGO correction, and then tune using the EGO correction gauge rather than the EGO voltage gauge. (ensure you have ego correction turned on by setting at least a 1 in the step size in Exhaust Gas Settings) If correction is below 100%, then lower the VE ("W" button) if its higher than 100% then increase the VE values (Q button) around the area the green dot is, and so on. Remember to burn the values every so often (Alt and B).It is also a good idea to save the file every so often too, try numbering them as you go so you can recall where you were, e.g. Drive1 Drive2, etc.

Re-Scaling the VE and Req_Fuel

If you have already started tuning but feel your Req_fuel is making the VE table too big or small then you can change the Req_Fuel but you will need to re-scale the VE Table too or the whole table will be out by the percentage of the change in req_fuel so your engine will no run like it used to. Re-Scaling is acheived by going into Basic Settings - Fuel Table 1 then select Tools - VE Specific - Reset Req_Fuel

e.g. VE table full of very low numbers (idle is around 15 and WOT is around 60-70) but drives well and AFR's are correct, then try decreasing the req_fuel value.
In this example we have dropped the req fuel from 14.7 to 12.2, this is roughly a 18% decrease in size, so the whole VE table will be increased by 18% to compensate.

Click OK then MegaTune will ask if you want to burn, I always select NO and then go into File - Burn to ECU

Tuning Issues

If you have a very long duration cam in your motor, and it idles poorly, you might be able to get it to idle better through careful tuning with MegaSquirt. Often a rough idle may be caused by lean air/fuel ratios. This is really is more of a cam issue than a fueling issue. The exhaust valve is held open later into the intake stroke and the intake opens earlier near the end of the exhaust stroke. At low speeds and relatively high intake vacuum you get more exhaust contamination of the fresh air/fuel charge. As you get more contamination of the air/fuel charge you typically need a richer mixture to get it to ignite and burn properly.

This means you probably cannot run a stoichiometric [chemically correct] mixture of 14.7:1 with your long duration cam. You need to run richer. So you tune your idle by ear rather than with a narrow band EGO [oxygen] sensor. And make sure you are not allowing EGO correction at idle if you have a rowdy cam! It will be trying to “correct” your mixture back to a lousy idle. If your engine will not idle well at stoichiometric mixtures, set the EGO Active Above RPM to a few hundred RPM above your idle speed. This will ensure that MegaSquirt does not try to lean the mixture back to stoichiometric to compensate for your adjustments.Remember that O2 sensors give wrong readings on a missfiring engine, big cams drive O2's nuts at idle too, so dont rely on their readings at idle.

Another tip you can try if you have a large overlap cam is to pinch off the MAP hose slightly while the engine is idling, and see if the idle quality improves. If so, then try a restriction in the MAP vacuum line. This has the effect of damping the vacuum pulses that the MAP sensor sees. Start with a ~0.040" (1.0mm) hole in the line. You may have to experiment with restrictor sizes to see what works best for your system.

Resets

A reset can be seen in Megatune in the bottom right hand corner. Some resets can be the USB adaptor (if being used) simply overflowing. If the engine runs smoothly but you are seeing resets and your using a USB adaptor try setting the Received and Transmitted buffers as low as they will go. If the engine is stumbling and there are resets on the Megatune screen (bottom right corner) then these are probably real resets, but to confirm this unplug the laptop if using a USB adaptor and see it if cures it. In datalogs you can see them as massive spikes in all of the logged variables.

Tuning for Economy

To get maximum fuel economy, you want the engine to run as slowly as you can (hence the proliferation of overdrive transmissions in the last 15 years), and to run an Air/Fuel ratio (AFR) of about 14.7:1 to 17:1.

To tune for economy with a wide band oxygen sensor is relatively easy. Look up the sensor output at ~16.5:1 for your sensor (~2.65 volts for the DIY-WBO₂, for example). Put that value as your EGO trigger point in MegaTune, and if your EGO ± Limit (%) is sufficient (given the state of tune of your VE table), you should be getting good economy.

You can try mixtures leaner than 16.5:1, however you may get a lean 'surge' that feels like someone is pushing the car forwards, then pulling it backwards. Generally, this is a sign that you are too lean.

With a narrow band, it's a bit tougher to set it for maximum economy. You can adjust the VE table, but the EGO correction tries to bring it back to a stoichiometric AFR.

You could raise your EGO_RPM_limit to just above your cruise rpm, but depending on where that is, it might not be all that workable. A better method, if you have a narrow band oxygen sensor, is:

new VE = {56% × (14.7 ÷ 16.5)} - 5% = 45%

Do this for all the values in the VE table you actually cruise at, but not the higher rpm, higher load areas of the VE table.

That keeps the EGO at 16.5:1 at cruise, but lets you set it anywhere else in the rest of the table.

Tuning for Emissions

To tune your engine for minimal emissions using MegaSquirt properly requires expensive test equipment. However, as a start, you can:

Here is an example of how a few changes affected one engine:

You can see that retarding the timing and leaning the mixture slightly gives the best possible compromise, increasing only the NO_x slightly among the regulated emissions. (The above was without a catalytic converter. With a converter, emissions would have been best at stoichiometric mixtures and the timing retarded somewhat.)

Spark Map Tuning

Before tuning the spark table ensure the Trigger Angle has been checked and set using a timing strobe, see HERE

Tuning the spark map may not seem the easiest thing in the world to do and it can be difficult to know where to start. Here is a base map that is for a Boosted engine (>100KPa = Boost)

Spark Map Tuning Basics - The idea is that the idle and low speed area's are retarded to around 8-20deg, usually idle will be around 8-12deg, but this depends on your engine's design. If you set the first row in the RPM range as a little under your usual idle (e.g.600 if your engine idles at 800ish) and add some advance here, so if the engine stumbles into this area the slight increase in advance will help it to speed up a little so it doesn't stall. The cruising area of the map should have a reasonably high advance, (low to high 30's) as the mixture will be reasonably lean and therefore will give a slower burn. The overrun area can have an even greater advance, this will allow you to run lean in that section. At Wide Open Throttle (WOT) the spark map needs to be RPM based (analogous to centrifugal advance on an old style distributor) coming in at the right rate relative to engine RPM. Typically, you want it "all in" by about 2800-3200 RPMs for a street performance motor.

Note the the optimum amount of total advance is not necessarily the most that doesn't cause detonation. For example, with a modern cylinder head design, you might get maximum power at 32°BTDC, but might not experience any detonation until 38°- 40°. However you will still want the advance to come in as quickly as possible (without knocking) up to 32°. For example, my Rover based V8 produces max power around 30°BTDC at WOT, but even at 36° at WOT, I have no detonation.
As the Kpa increases (load increase) the spark map should retard as the mixture will be richer and the chances of detonation will also increase with the load. When going into boost the advance table values will need to be lower than when out of boost (>100KPa = boost) and as the boost level increases the advance will need to decrease with it, as detonation is more likely. It has been said that 1deg of advance should be removed for every 2PSI of boost; this is simply a rough guide and lots of things can depend on how much to remove including compression ratio. Detonation Cans are a great option for tuning in boost, use a piece of copper pipe flattened at one end with a flexible tube connected to it. Bolt the flattened end to the cylinder head. Get an old set of ear defenders and drill a hole into the side of them, push the other end or the tube into the hole youve just drilled in the defenders and you should be able to hear any detonation as it occurs.

Crusing is probably the hardest part of the spark map to tune, so this will need several rows set up around that area, see setting the KPa and RPM rows for fuel HERE as it follows the same theory. Shunting in the crusing area is usually down to too much advance, or too weak a mixture. If the mixture is correct (14.7 to 13.5 depending on your cam) then it may be worth removing advance untill the shunting subsides. Too little advance will reduce throttle responce so don't go too far, too little advance can also create higher exhaust gas temperatures. Go back and check the AFR after tuning this area, as the spark angle will effect the AFR readings.

There is a thread on the MSExtra forum discussing spark tuning further that can be found HERE.

One thing to bear in mind is that altering the spark table WILL effect the AFR. So you will have to re-visit the VE table after tuning the spark table.

If you experience detonation in your engine, then either:

* Your mixture is too lean. Increase the numbers in the VE table at the point the engine detonates (or increase the Req_Fuel if the detonation occurs at all points). Also make sure your fuel pump is operating well. It may be supplying enough fuel at idle, but not supplying enough when the demand rises. Use the oxygen sensor readings to determine if you are lean,
* You have oil leakage into the combustion chamber (check the plugs for signs of oil). This could come past the rings or seals (possibly worn, or from something that was forgotten during assembly, or there are blocked drain back passages in the head, or the rings have been damaged by detonation or over-revving), a 'leaky' PVC system, or from a poor intake manifold gasket seal allowing oil into the runners (on push rod V-engines),
* Your spark advance may come in too far and/or too fast. Edit the spark advance table to lower the rate at which advance is added. You may also need to limit the total advance. Most engines will not require more than ~36° at WOT (possibly more for a flathead design, or a large open chamber, large piston dome design). Newer cylinder head designs and 4 valve/cylinders heads generally don't require a lot of advance,
* You have spark plugs that are too hot (get a range or two colder), or they are incorrectly torqued (if they are loose, they over-heat because of poor thermal contact with the head),
* Your thermostat is too hot (you can try as low as a 160°F thermostat for street use),

Setting the Acceleration Enrichments

MS2-Extra has blended MAPdot/TPSdot abilities for acceleration enrichment. You can select the proportion of each using the slider in the 'Tuning/Acceleration' dialog in MegaTune (the variable is called Tps_acc_wght in the code). If you choose 100%, you get accel enrichment based on TPS only, if you choose 0%, you get accel enrichment based on MAP only. Of course you can set it to any integer between these (99%, 98%, 97%, ... 3%, 2%, 1%, etc.) and get 'blended' accel enrichment.

The ‘regular’ acceleration enrichment is selected by default or when Enhanced Accel Enrichment is set to off.

The amount of acceleration enrichment is scaled from 100% down to 0 in the range from the Low RPM Threshold (100%) to the High RPM Threshold (0%). To defeat this scaling, set both Low RPM and High RPM Thresholds to a very large RPM value (greater than your redline).

The default values are a good place to start (especially if your req_fuel is somewhere between 10 and 20 milliseconds). (To convert v/s (used with older versions of MegaTune) to %/s, assume that 0%=0 Volts and 100% = 5 Volts (which isn't quite true, but it is a start), then 1.0 v/s = 20 %/s, etc.)

The values on the upper right are the TPS based values (as noted by the heading above them), those on the upper left are the MAP based values.

The two vertical columns show the current TPSdot and MAPdot values, with the recent peaks 'tell-taled' in red.

Larger values in the "Value (ms)" entries increase the amount of accel enrichment. Smaller values decrease the amount of accel enrichment.

The slider chooses the percentage of MAP versus TPS, somewhere between 30% and 60% is good for most installations. Some installations may need to use values outside this range to solve specific issues.

MS2-Extra also has user configurable accel taper tuning:

The accel time is time during which the full accel enrichment is added to the injector pulse width (in seconds not milliseconds). The accel taper time allows you to have the accel enrichment taper from the set value to the end pulse width gradually, rather than having the accel enrichment end abruptly.

Each of these accel enrichments schemes has it's own threshold (the rate below which no accel enrichment is applied). For MAPdot this is the MAPdot Threshold (kPa/s) (MapThresh), for TPSdot it is the TPSdot threshold (v/s) (TpsThresh).

By watching the bar graphs in the accel wizard, you can see how much noise there is in the respective sensor signals. try to set you threshold(s) above these levels to avoid unwanted accel enrichment, which can make you engine run very poorly.

After you have the VE table dialed in, then start adjusting the acceleration enrichment. You may want to try a short acceleration shot time (like 0.2 seconds) and increase the accel enrichment bins.

If the car does not buck under acceleration, you are close to correct settings. If it bucks and stumbles, then it is going too lean and you need to richen that part of the table. Before tuning decel [or accel], make sure you have your VE table close to correct first! One way to do this is to get the VE table set up by setting the TPSdot threshold setting very high (250 kpa/sec or 250 %/s, something like that) so that TPS enrich/enlean never kicks in. Then, (in steady state) set up VE table.

To adjust the accel bins, start with them high, then reduce the lowest bin value by 0.1 milliseconds at a time until the engine stumbles or coughs under gentle opening of the throttle. If it never stumbles, increase the rate at which you open the throttle and try again. If it stumbles even with the above values, double them and try again.

Then repeat with the next higher bin and slightly faster throttle movement. Continue with each higher bin and more aggressive throttle application until all the bin are satisfactory.

The Decel fuel amount (%) (TPSDQ) enrichment can be used to improve the economy of your vehicle. It reduces the amount of fuel injected when the TPS (and/or MAP) are decreasing. A decel fuel amount setting of 100% means no cut. 1% means reduce the pulse width by 99%, to 1% of what it normally would be. Note that decel 'enrichment' is ONLY applied above 1500 rpm.

EAE Tuning guide