Get your Power Commander II-equipped TL1000R to work right...

That is, if Dynojet delivers you a part that totally screws up your Throttle Position Sensor readings.


OK, so you've plugged in your new PCII, and your TL1000R idles like crap.  What can you do? Well, Dynojet
will tell you that the PCII is fine, but offer to take it back for testing.  Many members of the TL1000 list
have done this, but I decided to try and work around the problem (I'll be sending my PCII back this winter).

First, you'll need to check your Throtle Position Sensor (TPS) setting, using the diagnostic procedure
in the Suzuki service manual.  To do this, first locate the diagnostic connector - it'll be under the rear
seat, most likely between the inner and outer pieces of the tail section on the left side of the bike.

You'll want to insert a paper clip into the two populated terminals of this connector (it's a
four-pin connector - two are used, two are left empty).   Don't let the bare clip touch the
frame!


 

Turn the bike on, and you should see "c00" come up in the temperature display, like this:

Please note that bar next to the "c".  It has three positions, depending on the current reading
of the TPS.  With the bike set to idle at 1200 RPM, it should be in the middle position, as shown
above.  Bringing the bike up to approximately 1800 RPM and holding it there for over two seconds
(use the fast-idle lever) should bring the TPS reading high enough to show the upper bar, like below:

If you see the bar in the upper position (such as above) while the bike is set to idle at normal
speeds (1200 RPM or so), it's likely that your bike will "load up" and stall after idling for a few
seconds.

One solution is to adjust the TPS manually, so that you obtain the correct TPS setting with the
PC II attached.  I'll show you how to do this below.

First, remove the bolt attaching the damper to the frame, like so:

With this one bolt removed, you can swing the damper out of the way and gain enough room to
raise the tank.  Next, remove the rear seat by removing its two bolts, one of which can be seen
to the lower right of my thumb:

Remove the two bolts at the front of the tank, lift it up, and use the prop rod (located under
the rear seat) to hold it up.

You can see the TPS located at the end of my finger (uh, actually, you can't see a damn thing,
but I promise it's there!).  In case you can't tell, you're looking at the engine from the left
side of the bike, just in front of the rear cylinder head.  My bike doesn't have an airbox lid,
so there's no solenoid for the airbox damper actuators.  If you're still running the stock
setup, you'll need to remove the solenoid from the left rear of the airbox; no need to disconnect
any wiring or vacuum hoses, just the screw that holds it to the airbox.

There's two screws that hold the TPS to the rear throttle body; loosen these a couple of turns,
but do not remove them!  You only need them just loose enough to tweak the TPS setting a bit.

With the bike off and the idle set properly (that 1200 RPM setting again), you'll adjust the TPS
until the center bar shows up in the display.  You'll probably only need to tap the TPS slightly; make
sure you wait a couple of seconds between each adjustment attempt, or else the display won't
register the change.

Once this is set correctly, fire the bike up and set the idle to 1800 RPM or so.  You should see the
upper bar in the display.  If not, you need to adjust the TPS until you get the center bar at 1200
and the upper bar at 1800.

OK, so you've gone through all this, and the bike still won't idle right once it's warmed-up.  Time
for more drastic measures...

Start off by setting the TPS so the lower bar is indicated at 1200 RPM.  With my PC II, this is shown
as "-3% TPS" when it's plugged into the telemetry/programming software.  This allowed my bike to
run great at idle, but it barely would run at 4000 RPM.  It wouldn't pull cleanly, and would nearly
die if hammered on around this spot in the rev range.  Not cool.  Taking the Dynojet "Stage 2" map (301-001)
and adding or subtracting fuel in the  "AAP" (fuel) table didn't help one bit, and I tried a wide variety
of large and small adjustments.  So, I decided to add a varying amount of TPS signal in the "TPS" table,
varying the increase from 3-8% depending on where I thought the bike need it.

Click here to download my map.

Open it up using the Dynojet software and take a look before trying this on your bike.  Right now, I'm also
running an extra 5% fuel in the "AAP" map until I get the bike on the dyno; better rich than lean!

My bike now pulls hard from idle up to redline, with only a hint of stumble once the motor gets really hot
(such as after sitting in traffic for a while).  Somebody on the Turbobike mailing list put a Hayabusa on
their dyno, and found that the bike increases fuel delivery by 15% when the coolant temp goes over 225 F.
This is because the Suzuki EFI systems do not utilize a fuel return line, and the added fuel delivery is supposed
to keep the fuel moving through the system instead of soaking up heat.  It's not the best solution.
More work will be done  on the TL-R EFI and I'll continue updating this page.

EFI Basics

The TL1000 (and most other EFI Suzukis) use an EFI system that operates on as an alpha-n system at
lower throttle openings, and a speed-density system at larger throttle openings and engine speeds above
4000 RPM.  Say what?

OK, first a few basics.  Any EFI system operates on a very simple principle - measure the amount of air
entering the engine, and add the appropriate amount of fuel.  The Engine Control Unit (ECU) is the "brain"
that "looks" at the various inputs in order to determine the air volume entering the engine.  The operator
determines the amount of air by opening or closing the throttle.  The ECU adds fuel by opening a
fuel injector for a given amount of time.

The Suzuki system uses these sensors and inputs:

Manifold Air Pressure (MAP) - this measure the air pressure under the throttle blades.  More pressure
(less vacuum) under the throttle blades means more air enters the combustion chamber.

Throttle-Position Sensor (TPS) - this simply measures the opening of the throttle blades and sends the
appropriate voltage (between 0 and 5 V) to the ECU.

Intake Air Temperature (IAT) - this measures the air temperature, so the ECU can determine the outside
air density.  The sensor changes resistance with varying temperature (a chart can be found in the
service manual).

Barometric Pressure Sensor (BARO) - this measure the ambient barometric pressure, so the ECU
can determine the outside air density.

Crankshaft position sensor - the ECU determines the crankshaft position and speed by reading a
toothed wheel on the crankshaft.  It can fire the injectors at the appropriate time in the intake
cycle (typically, just before the intake valve opens) using this sensor and the...

Cam position sensor - this sensor allows the ECU to determine where each cylinder's progress in
the combustion cycle.  Without this sensor, the ECU can't determine if a piston at top-dead-center
(TDC) has just completed the compression or exhaust cycle.  With knowledge of the cam position,
this can be easily determined.

The engine speed, along with the MAP reading, calculated air density, and knowledge of the engine's pumping
efficiency (volumetric efficiency; discussed later), allows the engine to determine the necessary
fuel.  Since the ECU is using engine speed and air density, this mode of fuel calculation is refered to as
speed-density.

So what is this "alpha-n" stuff that was mentioned earlier?  At low engine speeds, the big V-twin (along
with its aggressive camshaft timing) causes some really large variations in MAP readings.  Apparently,
Suzuki couldn't figure out a way to filter this into a realistic average MAP reading, so they choose to
ignore the MAP sensor entirely and just use the TPS reading to determine the amount of air entering
the engine.  "alpha-n" refers to the fact that the engine is using throttle-blade angle.

Volumetric efficiency (VE) describes how much of the cylinder volume is filled during a combustion cycle.
At WOT, we'd like to fill the cylinder completely, as this gives us more mixture to burn.  The torque
curve of an engine follows the VE curve very closely (torque is directly related to combustion-chamber
pressure, which is related to cylinder filling - simple, eh?).  If you tune an engine for more upper-end
power, the VE curve will tend to shrink a bit at lower revs and increases at higher revs.  The VE curve
changes with throttle position, as the throttle's purpose is to restrict the air entering the engine.

The EFI system uses a table of VE curves at various TPS and MAP readings to determine how much air
filled the combustion chamber during a given cycle of the engine.  If you alter the engine's breathing
(through airbox mods, exhaust swaps, or internal engine work), you alter the VE curve, and therefore
you'll alter the fueling of the engine unless the VE curve is altered.

Roughly speaking, this is what the computer does when it determines how long to fire a fuel injector:


1: Determines air density by reading the IAT and BARO sensors.
2: Determines engine speed by reading the crank position sensor.
3: Looks up amount of air entering the engine by reading the MAP or TPS (depending on engine speed),
    and then using the VE table to determine % cylinder filling.
4: Calculates injector pulsewidth with the following formula:

    Injector pulsewidth = base pulsewidth x VE value x air density factor

5: Uses the crank position sensor to fire the injector at the appropriate time in the combustion cycle

OK, now that we know how the Suzuki EFI works, we can effectively tune the PCII.
 

Table 1: AAP (absolute air pressure, or something like that)


What we have here is a 3-D table that has the engine speed along one axis (the left side of the screen),
MAP along another (the top of the screen), and finally the desired % change in mixture (these are the table
values).

For example, if you wish to alter the fueling at 4000 RPM and wide-open throttle to add 20% more fuel,
pick the table location at 4000 RPM and 100% MAP, and place the value "20" in this location.
 

Table 2: TP (throttle position)

This alters the throttle position calibration.  If you need to alter the TPS mapping at a particular throttle
position and engine speed, you can do it here.  This mainly affects the fueling at low throttle positions and
low engine speeds.
 

Table 3: MP (MAP)

Just as the TP table alters the TPS calibration, the MP table alters the MAP calibration.  You can use this
to add or subtract fuel at 0% TPS and higher engine speeds to help reduce backfiring and throttle
sensitivity.
 

Table 4: Ignition (ignition timing)

This table maps ignition timing vs. throttle position (I think - this would be kinda weird, since timing is
usually referenced to MAP readings).  At engine speeds about 4000 RPM, you can add up to 5 degrees
of ignition timing.  I haven't seen any improvements by messing around with this table, so I'd recommend
that it be left alone for stock engines.  I think that you might benefit from advancing the timing if you
live at higher altitudes or perform extensive engine mods (like installing hotter camshafts).
 

I need to add some detail yet in the PCII table descriptions.  Additionally, I'm working on determining
how much adjustability there is in the stock ECU, as it'd be nice to eliminate the PCII "piggyback" and
make adjustments right to the ECU software.  Unfortunately, that's not looking likely, as it appears that
the stock mapping is stored in "masked ROM" (MROM) and isn't programmable.  The Yoshimura box
apparently can access a few bytes of EEPROM that act as bulk multipliers - you can change the fueling
in large segments of the map, but there's not much ability to fine-tune the stock map.  As I learn more,
I'll post it here.

Please email me with comments, questions or corrections!  eric@bryantperformance.com