Understanding your ECM
The ECM is the brains of your Buell, so using ECM Spy is almost
brain surgery! The ECM controls all your bikes intelligence, Fuel Maps,
Ignition Maps, Error codes and much much more. Key items you need to
understand to help tune your Buell are listed below.
Understanding the TPS
The TPS is the Throttle Position Sensor. The ECM needs to know how
open the throttle is, and in conjunction with the RPM, and atmospheric
conditions, it knows how much air is flowing and hence how much fuel to
inject. That is the essence of this tuning. If the TPS value is
incorrect, the ECM will provide the amount of fuel required for the
wrong throttle setting and hence poor running will occur. A worse
scenario is if you tune the bike with an incorrect TPS value, then any
future correction to TPS will result in incorrect fuel maps.
Understanding the AFV
The Adaptive Fuel Value is how the Buell automatically compensates
for changes to the environment, eg riding up mountains, or swapping the
exhaust silencer. It is not perfect, but does a good job to compensate
for minor changes. When the bike is ridden in Closed Loop mode
(explained next) the ECM monitors the O2 sensor and learns the
appropriate AFV value to apply to the fuel maps. This AFV value is
applied across the entire fuel map range, hence it is critical that this
is accurate. AFV values can vary from 80 to 160% but should be kept
between 90 and 110% whenever possible.
The AFV can be your friend, fine tuning the bike to suit your
location, or it can be your worst enemy! If you setup the bike on the
dyno for maximum power across the range, you will probably aim for
13:1–13.5:1 Air:Fuel Ratio (AFR). If you then go for a ride and
enter closed loop mode, the ECM will reset the AFV to maybe 80% to
reduce fuel and try to get the default 14.7:1 AFR. When you next
accelerate hard at full throttle, your perfect map as setup on the dyno
will now be running at 80% of your values hence weak!
To compensate for this, it is recommended when on the dyno to
disconnect the O2 sensor, reset the AFV to 100%, then tune the bike for
an Air Fuel Ratio of 14.7:1 within the closed loop area. This will then
allow you to set the Air Fuel Ratio for optimum power in the high rpm,
throttle areas. Always reconnect the O2 sensor after tuning and check
the AFV periodically.
So what is Closed Loop?
The Closed Loop area is found when riding in low throttle positions
at low rpm, but not under stress. I believe this is approximately
1500–4000rpm and 10–30% throttle.[1]
Riding in Closed Loop allows the ECM to reset the AFV and compensate
for the environment. It is good practice to do this periodically. Normal
riding conditions will normally include Closed Loop riding for long
enough. To ensure the AFV is about right for your setup, try and do a
few miles on flat roads between 40–70mph and low throttle
openings, with a steady throttle. This should set the AFV. If you have
the time, you could try riding at 2000 rpm for a couple of miles and
check the AFV. Next try 2500 rpm and check, then 3000 and 3500. This
would validate your map in this region of Throttle / RPM combination,
but is a lot of effort! Remember with a narrowband O2 sensor
(standard one) the readings are very slow to respond, hence the steady
riding required to adjust the AFV.
[1] For the XB9 engines, closed loop seems to be
between 1000-5000 rpm. (Gunter)
Understanding the Fuel Map
The Fuel Maps control how much fuel the injectors will flow for any
given RPM and Throttle Position combination. The values in the table
relate to the length of time the injector is open (pulse width) and
flowing fuel. It is assumed that you are not modifying the injectors or
the fuel pressure, hence the only variable is the pulse width of the
injector. For the technically minded, each value in the table equates to
58 Microseconds of injector pulse width duration.
The fuel map shows the Throttle Position Sensor values on the left
and the RPM across the top. Low Throttle, low RPM is on the bottom
left, with full throttle, high RPM on top right.
Areas of the Fuel Map
The Fuel Map can be broken down into different areas which affect
different combinations of throttle position and rpm as you are riding.
The following table is intended to help explain the areas of the fuel
map and how they relate to riding the bike on the road. It is only an
indication, but should help you understand how the map works!
RPM→
↓TPS |
0 |
800 |
1000 |
1350 |
1900 |
2400 |
2900 |
3400 |
4000 |
5000 |
6000 |
7000 |
8000 |
| 255 |
Zone 7 Maximum Throttle, Low RPM |
Zone 8 Full Power Through The Gears |
Zone 9 Full Power Maximum Throttle |
| 175 |
| 125 |
| 100 |
| 80 |
Zone 4 Pulling Away! |
Zone 5 Cruising Midrange |
Zone 6 Accelerating Into Corners |
| 60 |
| 50 |
| 40 |
| 30 |
Zone 1 Startup and Idle |
Zone 2 Closed Throttle Overrun |
Zone 3 High Speed Closing Throttle |
| 20 |
| 15 |
| 10 |
Note, the XB12 redlines at 6800RPM, the XB9 at 7300RPM, hence the
final column will hardly be used on a Buell!
Front and Rear Maps
The Buell and most air cooled in-line V Twins runs hotter on the
rear cylinder than the front one due to airflow across the fins. To
compensate for this Buell design the ECM with separate tables for Fuel
and ignition on front and rear cylinders.
The rear cylinder should normally be similar, but slightly richer
than the front cylinder in any area of the fuel map.[1]The O2
sensor is installed into the rear header to ensure that the hottest
cylinder is the one being measured for Air/Fuel mixture.
Whenever tuning the bike, unless you have sensors in each header,
always make identical changes to front and rear cylinders
simultaneously. Failing to do this could result in the mixture being
correct on one cylinder, but incorrect on the other!
[1] We found out recently, that even if the maps
are identical the rear cylinder is running a bit richter than the front
one. (Gunter)
Tuning!
OK, you've seen this before, but time for some more explanations!
This really is the key to finding the areas of the fuel map where the
bike needs tweaking to solve a problem!
Under normal circumstances, the values in cells should be
comparable to adjacent cells! You should not have
one cell with a value of 10, adjacent to another cell with a value of
200! Just take a look at your map for anything which stands out and try
to smooth out the values, ideally by increasing one value if possible.
This is important at the end of the process to ensure a smooth power
delivery from your Buell.
If in doubt, increase a value in preference to reducing another!
Remember a rich mixture is much safer than a lean
one!
When modifying the cells, make sure you modify a couple of cells
either side of the actual one you are interested in, just to keep the
map smooth as you work. Make small changes and test it then try again.
With intuition you will learn how much to adjust to get it right.
Unless you are measuring the mixture in both headers accurately,
always make sure you modify the front and rear maps by similar amounts.
Standard principles apply when tuning: if you are bogging down, you
normally remove fuel. If it feels "fluffy" then add fuel. If
in doubt, ride it, add fuel, try it again, if worse, then remove fuel!
The Tuning Zones
RPM→
↓TPS |
0 |
800 |
1000 |
1350 |
1900 |
2400 |
2900 |
3400 |
4000 |
5000 |
6000 |
7000 |
8000 |
| 255 |
Zone 7 Maximum Throttle, Low RPM |
Zone 8 Full Power Through The Gears |
Zone 9 Full Power Maximum Throttle |
| 175 |
| 125 |
| 100 |
| 80 |
Zone 4 Pulling Away! |
Zone 5 Cruising Midrange |
Zone 6 Accelerating Into Corners |
| 60 |
| 50 |
| 40 |
| 30 |
Zone 1 Startup and Idle |
Zone 2 Closed Throttle Overrun |
Zone 3 High Speed Closing Throttle |
| 20 |
| 15 |
| 10 |
Zone 1 — Start up and Idle [1]
This Zone is self explanatory, if the bike is ticking over happily
when warm, you probably don't need to
adjust this area at all. If the bike is struggling on tick over, check
for air leaks first before adjusting the fuelling. If the bike is trying
to stall, it's possibly rich and may need to reduce the figures in Zone
1. If it's hunting for more rpm then it may be running slightly lean.
Let the bike tick over as best it can and check the Fuel Map screen
in ECM Spy to see where the ECM is currently
working. You should see the ECM moving around in a small area of the map
as the rpm changes.
Zone 2 — Closed Throttle Overrun (The Popping
Zone!) [1]
This will be one of the most noticeable areas where you can improve
your fuel map! Popping is usually caused
by either rich mixture or air leaks in the exhaust system!
First thing is to check for leaks! Check where the headers are
fitted to the barrels and on any slip joints on your exhaust. Normally
you can block the tailpipe loosely with a gloved hand and leaks are
fairly easy to find!OK assuming you have no leaks, then you can try
adjusting the mixture. Zone 2 is only ever going to be used when you are
slowing down under engine braking with a closed throttle. This is
probably the safest area on the fuel map to actually remove fuel. Never
remove all fuel in this area, as you need some to lubricate the engine,
but try reducing it in small amounts to see if you can improve the
popping. It is likely that you will not remove the popping completely.
Zone 3 — High Speed Closing Throttle
This is effectively the same as Zone 2, but more critical that you
keep some fuel in there as the engine is likely to be hot when you are
in this zone.
Alternatives to adjusting fuel in Zones 2 and 3, could be to reduce
the values in the Decel table. [2]
Zone 4 — Pulling Away [1]
OK, so this is the mid throttle, low rpm area, most often used when
pulling away or gently accelerating through
the gears.
Zone 5 — Cruising Midrange [1]
Mid throttle, Mid RPM, probably the most commonly used zone on your
ECM during normal riding.
If you have modified your bike in any way from standard, then
hopefully you've increased the air flowing through the engine. As a
result, you should really only be adding fuel in this area. Only remove
fuel here if you are really sure.
Zone 6 — Accelerating into Corners
Not technically accelerating, but attacking the corner by letting
the engine braking keep the rpm high, then holding the throttle in mid
range, ready to go full throttle as you exit.
This is another area where care is important when tuning as the
engine is under significant load in this zone. Dyno or wideband tuning
are essential if modifying this area.
Zone 7 — Maximum Throttle Low RPM
Rarely used, except on the dyno, or when popping the front wheel up
from a clutch less wheelie!
As per the others, bogging = remove fuel, fluffy = add some!
Zone 8 — Full Power Through The Gears
Ok, another important area of the map! Accelerating hard out of a
corner, or just going hard up through the gears
This is another area where care is important when tuning as the
engine is under significant load in this zone. Dyno or wideband tuning
are essential if reducing any values in this area.
Zone 9 — Full Power Maximum Throttle
Full Throttle, Maximum RPM, enough said!!!
This is the most critical part of the map, as it is the one when
the engine is under the most load, being ridden the hardest. Get it
wrong here and it will be expensive!
This is another area where care is important when tuning as the
engine is under significant load in this zone. Dyno or wideband tuning
are essential if reducing any values in this area.
Seat of the Pants!
Possibly the most common method of tuning, definitely was the way 20
years ago! Some people have "The Knack" others definitely
don't! We do not recommend this method, as it is possible to make the
bike feel good, but to have dangerous weak spots you have missed! You
need to understand your bike and know how it is responding, making
mental notes as you ride and writing them down at the side of the road.
You will need to ride through all the normal conditions you ride in,
noting how the bike responds on different throttle positions. If you are
going to do this properly, you need to mark the throttle at different
positions you can equate back to the ECM maps. Hold the throttle at
specific positions, and note the performance as the RPM increase. Pull
over, note the responses,
then try again at the next throttle position. Repeat until finished!
As a guide, if the bike is "bogging down" then it is
rich. If it is "fluffy" then maybe weak! If you are not sure,
make a note of the current settings, then add fuel. If it is better,
great, if worse, then go back to the old setting and reduce it only a
small amount. Always take care if reducing any settings below the
original values!You will need to keep repeating this process for all
parts of the Throttle / RPM combinations to try and find any areas where
it is not performing properly.
Checking the Mixture!
Checking the fuel when tuning by seat of the pants is usually done
by checking the plug colour! You really don't want to be doing this on
your XB! Ride on a steady throttle, holding a specific RPM, ride like
this for a mile or so, then clutch in and kill the ignition immediately.
Coast to a stop, then pull out the plug and check the colour!
White plug = Lean mixture, add fuel to or risk damage to your
bike [3]
Black oily plug = Rich mixture
Light
brown plug = All is well, the mixture is good (At this TPS / RPM
combination only!)
Repeat for all throttle positions, in particular Zones 5, 6, 8 and
9, and when all zones are between tan and chocolate brown, you are
finished! There is no guarantee that your mixture is totally correct,
even with tan coloured plugs from this, but the bike should be ok to
ride.
On a Dyno
Probably the best way to get the fuel maps right, as long as the
dyno operator is good and knows a few basic facts about the Buell ECM.
Always check or reset the TPS before setting up the Buell on a
dyno. If this is not done and the TPS is out, then all maps setup on the
dyno will be out by the same amount when the TPS is next reset. This can
easily be done by the owner before going to the dyno shop. Don't waste
your money asking the dyno operator
to do this!
Reset the AFV to 100. This is also essential and should be done
immediately on arrival at the dyno shop. If the AFV is above 100 when
you start tuning, it will be adding fuel above the closed loop area.
Disconnect the O2 sensor! That's right, disconnect it before tuning
on the dyno. If you leave it connected when setting up the ECM in the
closed loop area, the ECM will adjust the AFV value and screw up the
tuning! Remember to reconnect it when you have finished. The Buell ECM
must be tuned for 14.7:1 Air/Fuel mixture in the closed loop area.
Tuning for anything else will cause the ECM to set the AFV to correct
it. End result will be incorrect maps outside of closed loop and
potential risk of engine damage!
If the dyno operator can measure front and rear cylinder mixtures
independantly, then go for the best he can do. If not, make sure both
cylinders get the same changes or you could run front spot on, and the
rear lean!
Always check the AFV value after tuning, it should be at 100 as the
O2 sensor has been disconnected. Test ride the bike, ensuring you do
some closed loop riding, then check the AFV again it should be between
90 and 110.
CARE: It is known for a Buell to be setup perfectly on the dyno
with the O2 sensor connected, but then to go off when used for a few
hours. This is almost always because the O2 sensor was left connected,
the bike goes through closed loop riding and adjusts the AFV.
Datalogging
Datalogging is the most accurate way to tune your bike and get it
absolutely spot on! It is the only way
to know what your bike is really doing in the real world. The only
problem is that to do it right, it isn't free!
Using ECM Spy or ECM Spy Palm, you can log your ECM values, but you
will only be able to get the accurate air fuel mixture if you use a
wideband O2 sensor.
The idea is that you connect up your logging equipment (Laptop,
palm, or hardware) then go and ride the bike! Try to go through all the
normal riding conditions a few times and get as much data as you can.
- Standard Narrowband O2 Sensor: The standard Buell O2 sensor is ok
for steady closed loop riding, but does not respond fast enough and is
not accurate enough for full tuning of the ECM.
- Using a Wideband O2 Sensor: Wideband sensors react much faster and
provide more accurate measurements than narrowband, hence are
recommended for accurate tuning on the road.
Analyse the data and create the new maps
Analyse the data on your laptop, in particular, looking for the
mixture against throttle and rpm. You should now be able to map the data
to give you an average reading for every Throttle / RPM combination.
Working out the new map involves finding the Throttle / RPM
combinations which are giving poor mixture values and adjusting the map
to correct. You are looking to achieve optimum Air / Fuel ratios in
different areas of the map, which does not mean making them all the
same! When in the closed loop area, you must aim for 14.7:1 whereas in
zones 8 and 9, richer mixtures up to about 13:1 will give you better
performance.
The table below shows an example of an Air / Fuel map with closed
loop and other areas running on AFR 14.7:1 to give ideal fuel economy.
The map then adds fuel when the throttle is opened up to give a more
powerful richer mixture, peaking at 12.8 for maximum power, then 12.6 to
go slightly too rich on maximum rpm.
It is important to note that this is not a genuine map from logged
data on a bike. It is just to indicate the type of figures you are
looking for.
RPM→
↓TPS |
0 |
800 |
1000 |
1350 |
1900 |
2400 |
2900 |
3400 |
4000 |
5000 |
6000 |
7000 |
8000 |
| 255 |
14.7 |
14.0 |
13.8 |
13.6 |
13.5 |
13.5 |
13.5 |
13.4 |
13.2 |
13.0 |
12.8 |
12.6 |
12.6 |
| 175 |
14.7 |
14.0 |
13.8 |
13.6 |
13.6 |
13.5 |
13.5 |
13.4 |
13.4 |
13.3 |
13.0 |
12.8 |
12.8 |
| 125 |
14.7 |
14.0 |
14.0 |
13.8 |
13.8 |
13.7 |
13.7 |
13.6 |
13.6 |
13.5 |
13.5 |
13.0 |
13.0 |
| 100 |
14.7 |
14.7 |
14.0 |
14.0 |
14.0 |
14.0 |
14.0 |
14.0 |
14.0 |
14.0 |
13.8 |
13.5 |
13.5 |
| 80 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.0 |
14.0 |
14.0 |
14.0 |
| 60 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.5 |
14.5 |
14.5 |
14.5 |
| 50 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
| 40 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
| 30 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
| 20 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
| 15 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
| 10 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
14.7 |
Look out for areas like this in your maps:
| 13.5 |
13.4 |
12.4 |
13.3 |
13.0 |
| 13.7 |
13.6 |
15.2 |
13.5 |
13.5 |
| 14.0 |
14.0 |
14.0 |
14.0 |
13.8 |
| 14.7 |
14.7 |
14.7 |
14.0 |
14.0 |
The blue value is rich, with the red value below running weak.
These could appear to be correct when riding as they could compensate
for each other, but really need tuning out. Look at the percentage the
value is out and reduce the appropriate fuel map cell by the same
amount.
Road Testing
So you'e finished tuning the bike and the dyno figures or data logs
look as good as you can get, time
to go for a ride! Before you do, a few checks:
- Is the O2 sensor connected?
- Are there any unexplained error codes? Should be one for the O2
sensor at least! Clear them!
- Did you take out the headlight fuse? If so, stick it back
in!
- And lastly, how's the fuel? It easy to burn a lot of it on the
dyno or when testing!
Gloves, Crash Helmet, leathers, reflective jacket! (Well this is
meant to be a safe tuning guide!!)
Now ride it! Test everything, listen for popping on the overrun,
feel the throttle and remember anywhere it feels wrong! Is it fluffy or
boggy anywhere? Hopefully not! Make sure you ride it in closed loop for
a while 2-3 miles minimum, then go through all Throttle / RPM
combinations. Back to the garage, riding the last mile in closed loop if
possible. Do not leave the bike ticking over when you arrive, just
switch it straight off.
Checking AFV Value [3]
Plug in the laptop again and check the AFV. You want a figure
between 90 and 110, ideally as close to 100 as possible.
If you have a low AFV value, you are too rich on your map within
the closed loop area. This is dangerous as it can cause lean fuel in
open loop! If you have a high AFV you will be too weak in closed loop
and the ECM is compensating, but could leave you rich in open loop.
Check for Error codes
Time to check for error codes again, there should be none this
time! If there are, deal with them!
Backup Config again!
OK, time to do a full backup of the ECM, the EEPROM and also the
fuel maps! This is your bike running at its best, save that data
somewhere safe!
Riding Normally
Use the bike now and enjoy it! Make notes if anything feels or
sounds wrong, otherwise just have fun. It should be crisp across the
range and running well. Burn at least a tank of fuel, in normal riding
conditions. If anything is wrong, just perform minor tweaks in those
areas.
Checking AFV again! [3]
Check, check and check the AFV again! If it's out by more than 10%
then you need to adjust your map!
Enjoy!
Well that is why you °re doing all this isn't it?
[1] Zones 1, 2, 4 and 5 are (mostly) within closed
loop if the O2 sensor is connected. Thus effects to map changes might
not be as expected. The ECM will keep the mixture to 14.7:1 AFR.
(Gunter)
[2] A deceleration fuel cut table has not been
identified in the EEPROM data yet. (Gunter)
[3] Take into account that AFV also reacts to
climatic changes as air pressure or (much less) air humidity. So try to
run tests on similar weather conditions and do not change altitude
between tests. (Gunter)
