Wren Turbines Xicoy AU-107K ECU User manual

Kerostart supplement
for Wren 44 Gold Thrust,
Turboprop and Heli engines
Feb 2012

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 1
Wren 44 Kerosene Start Supplement
This supplement is supplied to assist Wren 44 owners to install
and operate the new Wren kerosene start system with Xicoy
Au107K ECU. This system replaces propane start components
except the valves which are retained. Propane tanks, flow
controls, filling valves etc, are no longer required. The green
propane feed pipe should be blanked off close to the engine.
PLEASE NOTE – If you have bought an engine from Wren
Turbines with a kero start fitted, PLEASE DO NOT jump in and
change the settings supplied as the engine will have already
been carefully set up ready to run.
Setting up the kero-system is straight forward but users are
requested to take particular care in setting values to the ECU.
The ECU allows access to all values held in the memory. Most
should not need adjusting and customers are asked to refrain
from making changes to these values as they may have a
significant effect on the engine starting and operation.
Those settings which access IS needed are described in the
checklist. These notes are not intended to replace the existing
instructions and users should refer to these for guidance on
installation and operation.
The installation assumes the engine is fully serviceable and is a
current Wren 44 Gold unit. Contact us first if your engine is an
earlier model. Fitting a kero-start system will not cure a poorly
starting engine – so be sure your engine is in good working
order before fitting. If you are unsure of the suitability of your
engine please contact Wren Turbines Ltd.
All Wren 44 Turboprops and 44 Heli’s are based on the 10Lb
thrust Gold engine so if you have one of these this system will
be suitable. The system requires a LiPo battery of 1800mAh or
better. A C-rating of 20 or more is needed.
The operation of the fuel pump is more critical in a kerostart
system as the fuel pump must be able to reliably run at a slow
power setting. For this reason we use a fuel pump made
especially for small engines. Other pumps are not suitable.
Operation of the two valves is also critical as rapid switching of
these is used to regulate fuel flow at the starting, these
components must be in perfect order. The brass type are
suitable and have proved reliable.
Fuel must be kept clean and free of water ingress – even tiny
amounts can make deposits on the pumps gears and spoil the
valve seats and make successful kerosene starting impossible.
Inspect your fuelling equipment and filters regularly and dispose
and replace any fuel with water or particle inclusions.
This manual and the pictures and data included are copyright of
Wren Turbines Ltd and may not be used without their
permission.
Wren Turbines Ltd are at:
Unit 19, Century Park Network Centre, Dearne Lane, Manvers,
Rotherham, South Yorkshire, England. S63 5DE.
Tel. [phone]. Fax. [phone]
Email: [email protected]

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 2
How does it work?
The kerostart system is basically an alternative form of heating
from the propane system used in gas start engines.
Heating is achieved by igniting and burning a small amount of
fuel using a small plug called the Burner. This is a small ceramic
element enclosed in a stainless steel housing with a very small
clearance around its tip. The housing fits the normal glowplug
hole and uses the same glowplug cable.
The element is heating by passing electrical current through it
and its tip glows bright orange (voltage set in (“Glowplug
Power”). Kerosene fuel is then pumped through the narrow gap
next to the glowing element and it bursts into flame. This flame
then provides enough heating in the combustion chamber to
allow fuel to vapourize when passed down the vapourizer tubes
in the normal way.
The amount of fuel used for the burner is very small and the fuel
pump is unable to run this slowly in a reliable way, so the
solenoid valve supplying the burner switches on and off rapidly
to help regulate the flow. The longer the valve stays open the
more fuel passes and this is how the ECU controls the flow.
The setting for this is important as too little flow and there will
only be a small flame, but too much and the element may be
cooled so much the fuel fails to ignite into flame. Also, if the
engine is spinning too fast while the small flame is going it may
blow the flame out so rpm must be carefully controlled (“Starter
Power at Ignition” and “RPM Ignition Kero”).
This stage is called Ignition.
In the ECU, the amount of fuel fed to the burner is controlled by
the function “Pump Power Ignition Kero” in the START menu
and the engine speed after the burner has ignited, is controlled
by “RPM Ignition Kero”.
Once the ECU has seen enough temperature rise from the small
flame it will begin pulsing the main fuel valve to the combustion
chamber in addition to the burner - a very small amount initially
so as to establish combustion properly. This stage is called
Preheat. Functions used at this stage are “RPM Preheat Kero”
(sets the rotor speed at this point) and “Engine Preheat Fuel”
(amount of fuel allowed into chamber).
Once the ECU has seen enough temperature rise (set in “EGT
End Preheat”) it will gradually increase the starter speed and
main fuel valve opening time to increase the fuel flow to the
main chamber and conversely reduce fuel flow to the burner
until it is shut off completely. This stage is called Switchover.
At switchover the fuel pump is driving at a new rate set by a
number - “Pump Start Point” and the rate of increase of the
starting is set by “Pump Start Ramp” and the initial %flow
through the fuel valve is set by “Engine Min Flow”. This %flow
and increasing rpm continues increasing as the engines
accelerates up to the point where the fuel valve is 100% open –
display shows “FuelRamp”. The fuel pump power keeps rising
until the starter is no longer needed (“RPM Off Starter”) and
continues until the engine reaches the idle speed set.
Note we have highlighted “Pump Power Ignition Kero” and
“Pump Start Point” in red as these are the main adjustments
needed to “tune” a new fuel pump or adjust for a worn one.

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 3
Xicoy Fadec
Au-107K ECU
Valve
Valve
Pump
7.4V
2cell
LiPo
Throttle signal
Starter
motor
Fuel
Igniter
Fuel tank
Receiver
BATTERY
PUMP
GAS VALVE
KERO VALVE
GLOW
STARTER
Data
Terminal
RPM sensor
Temp sensor
RPM
TEMP
Throttle In
Igniter Plug
Connection Schematic for Fadec Xicoy AU-107K ECU.

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 4
Components required for 44 kerosene start installation:
44 Gold Engine (thrust, heli or turboprop)
Xicoy AU-107K ECU (pre-programmed for 44 kerostart)
3-wire type Data Terminal
Hausl ZP25M14 magnetically coupled fuel pump
Two valves c/w 3mm push-in fittings, (brass type)
Wren kero burner
3mm ptfe burner feed pipe and inline connector
3mm T or Y connector
3mm fuel piping
2-cell LiPo 1800mAh, 20C rating battery
Xicoy AU-107K ECU showing plug locations.
See text for details on what plugs in where.
Quick start installation, mechanical:
Position the fuel pump, ECU and valves. Place valves as close
to engine as possible.
Screw burner onto engine plughole using earth terminal above
the banjo fitting.
Rotate the burner feed into the
direction to suit your install
before tightening.
Fit plug cap to burner nipple.
Push on ptfe 3mm tube onto burner nipple and slide green gland
nut over top and screw on firmly/gently.
Connect inline 3mm fitting to end of burner ptfe tube.
Connect a short (20mm) 4mm tube onto fuel pump inlet
and longer 3mm tube to outlet.
Push on Tygon feed from tank onto 4mm pump tube.
Position T connector close to valve inlets and connect pump
outlet to T inlet with 3mm tube.
Connect T outlets to each valve with 3mm tube.
Connect one valve output to engine fuel inlet with 3mm tube.
Connect the other valve output to the burner feed fitting with
3mm tube.

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 5
Quick start installation - electrical:
Refer to the picture of the ECU on previous page for plug
locations.
Plug burner valve to the 2-pin socket marked as “Gas valve” on
ECU (see top left).
Plug engine fuel valve to adjacent 2-pin socket marked “Fuel
valve” (extreme top left), note – this label is on side of ECU.
Plug in the receiver throttle signal wire from receiver to the plug
marked “Throttle input” (see bottom right).
Plug in the engine rpm sensor to the 3-pin plug marked “RPM
sensor” (bottom right).
Plug in the engine temperature probe to the 3-pin plug marked
“Thermocouple” (bottom right).
Plug in the glow/starter cable from the engine, using extension if
fitted, (see top right).
Plug in the battery/pump cable (top left). Leave the battery end
unconnected at this stage.
Plug in the data terminal (bottom left). A standard servo type
extension cable can be fitted to the model to allow convenient
access, if required.
Setting up ECU (Engine Control Unit)
Remove all rates, mixes and throttle travel settings in the
transmitter. The setup assumes the use of a transmitter with
manual trims.
Digital trims and Throttle-Cut function.
If you have a transmitter with digital trims you can simulate the
trim up/down function using the “Throttle Cut” switch, which is
usually a function switched through a toggle switch mounted on
the transmitter (must not be spring loaded). Consult your radio
manual for this function. Setting the ECU using the “Throttle Cut”
function is done in the same way except that when “trim-up” is
required you switch the “Throttle Cut” to off, and when trim-down
is required, you switch to “Throttle Cut” on.
For initial testing the normal digital trims can be used if you don’t
want to have to explore the “Throttle Cut” function just yet. The
trim up/down function is used to switch the engine to “ready to
start” and “off”, and would not normally be used to vary the idle
rpm. Note - some transmitters may need throttle reversing - see
later.
As the display does not photograph well we have reproduced
the display readings as a green box.
Turn on the transmitter and receiver. On power-up the screen
should come on and after a few seconds should stabilise to the
opening screen and should
show as right:
(If the temp’’ probe is not
connected it will show as 0’C). “T” = ambient temp’.
Trim Low
T=020’C
RPM 00000 PW 000

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 6
There are four buttons on
the display. The buttons
are:▼▲-+.
To scroll through the different screens use ▼▲.
The buttons - + are used to change the values stored.
Press the Up button (▲)
and scroll through the
menus until you find the one
showing :
Press the minus (-) button and the screen will change to:
Press the +button to enter
the radio setup screen. You
should then see this screen:
On your transmitter, place the
throttle stick and trim to maximum
and press the +button to set the
value into the ECU.
The screen will now change to:
Move the throttle trim (or switch
the “engine cut” switch to on) and
throttle stick back to zero and
again press the + button.
The display will now change to:
Leaving the throttle stick in the
minimum position, raise the
throttle trim to the max position or
switch “Engine Cut” switch to off,
and again press the +button.
The display should then show:
Lower trim to zero. Now switch off the receiver.
Turn the receiver on again, if you have done all the steps
correctly the opening screen will show “Trim Low” and if you
raise your trim to full it should change to “Ready” and a blue led
will light on the ecu. If not, you will need to reverse the throttle
channel on your transmitter and repeat the radio setup.
This completes your radio set-up. It should only need doing
again if the radio settings are changed or installation moved to
another radio but it is worth rechecking periodically.
Stick Down
Trim Up (Idle)
Thrust curve:
LINEAR
Transmitter
adjust Enter
Stick Up
Trim Up
(Full power)
Info
Run
Start Radio
Stick Down
Trim Down (Stop)
T=020’C
T=020’CT=020’C
T=020’C

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 7
Setting up to run engine:
Turn on the receiver and verify the screen shows a reading.
Go into the 3rd screen and enter the “RADIO”menu and
perform the transmitter setup if not already completed.
Connect the LiPo battery. Turn on fuel if you have fitted a shutoff
tap between pump and valves (preferred position).
Ensure trim and stick are at zero. Enter “INFO” menu and go
down the entries until you get to “test” functions. Find
“Test/Prime Pump”. Press “On” button to turn on fuel pump and
watch fuel travel along from the tank to the engine. Press “Off”
to stop.
Go further down “INFO” menu to “Prime Burner On Off”. Press
“On” button and watch fuel travel to burner, then press “Off” to
stop. Do not prime longer as you risk pouring fuel into the
engine which will cause a flaming start. Small bubbles in the
pipes at this stage will not prevent a start, just delay it.
Place the engine/plane into a suitable place and prepare for a
start. Use helper if required to restrain model.
Position fire extinguisher – if you get into trouble place trim
down, stick down immediately to halt the start. Then energise
the starter by raising the stick to full to spin the engine up to
clear.
If you have a fire, position C02 extinguisher nozzle at engine
intake and use short bursts to put out.

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 8
Starting the engine.
Turn on transmitter and receiver.
Plug in display - screen shows “Trim Low”
To initiate the start, raise trim to full, ((led in ECU lights and
screen shows “Ready”). Place stick to full and back down
quickly. (Holding the stick at full will spin engine at full power –
can be used to cool down from a previous hot start or run)
Starter will spin engine briefly and then power igniter (screen
shows “Glow Test” then “Burner On”).
To initiate start without spinning engine raise trim to full, raise
stick half way and back down.
Igniter will heat and after some seconds starter will spin engine
slowly, pump will turn on slowly, igniter valve ticking. If pump
does not come on raise “pump power ignition kero” until it does.
You should hear a pop and combustion starting in the engine
and temperature rise on the display. (Screen shows “Preheat”).
If too gentle, increase “preheat fuel”.
After some seconds engine speed and temp’ will increase, valve
pulsing will speed up and the main fuel valve begin to open and
engine begins accelerating towards idle. (Screen shows
“Switchover” then “Fuel Ramp”). If engine stops at switchover,
increase “pump start point” until it continues. (Sometimes needs
to be “50” or more).
If the engine slows down or makes smoke at switchover,
increase the value for “min flow” as the flow is not high enough
to make a successful switchover.
At the end of “switchover”, burner turns off at around 20,000rpm,
and “fuel ramp proper begins”.
Engine continues accelerating and starter turns off as it passes
30,000rpm.
Engine arrives at 55,000rpm - idle, (screen shows “Running”).
You now have control of engine via throttle stick.
At any time the start can be terminated by lowering stick and
trim to zero. The throttle stick can then be used to switch the
starter to clear/cool the engine.
After running.
After running or flight, raise rpm to 80,000rpm for ten seconds
and lower stick and trim to zero for cooling.
ECU will spin engine in short bursts until the temp reading goes
below 100’C where it will stop. If temp rises above 100’C again
ECU will spin the engine again until below 100’C.
Once cooling is complete display shows “Stop”.
You can turn off receiver and transmitter and disconnect LiPo
battery, if this is the last run for a while, or you need to recharge.
Never recharge a LiPo whilst installed in a model.

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 9
Settings used in ECU.
A Wren supplied kerostart engine package will already be
adjusted for optimum ECU and pumps settings and should need
little or no attention, so do not fiddle with the settings.
As the fuel pump wears it may be necessary to adjust settings –
see later.
An upgrade set of kerostart parts will have the ECU supplied
pre-programmed with initial values but may need tuning to get
clean and secure starting for the particular engine and install.
Please note, no two installations will be truly identical so do not
swap settings with a colleague with a similar engine as they will
most likely not be compatible.
If the fuel pump is replaced, new settings may be required as no
two pumps have precisely the same characteristics.
A problems checksheet follows in the next couple of pages. It
lists common faults and the likely cures and hopefully will solve
your problem quickly.
Please use the checksheet before calling us – it is there to help
you to save time trouble and expense.
If you find something not covered then of course mail us with a
description and we will try to help you: in[email protected]
Please note, we can only help users with a kerostart issue on a
Wren engine.
ECU default values and adjusted settings:
Item: Initial value: Your values:
Pump start point 030-50
Pump start ramp 004
Glow power 6.9v
Low battery volts 6.0v
Starter power at ignition 060
Starter power at fuel ramp 070
RPM point 100% starter power 25,000
RPM starter off 30,000
RPM reconnect starter 27,000
RPM Ignition kero 7,000
Pump power ignition kero 31-50
Engine min flow % 55-60
EGT end preheat ‘C 180-200
RPM preheat kero 12-14,000
RPM fuel ramp kero 20,000
Preheat fuel 50-70
Ignition timeout sec’s 24.5
*Items highlighted adjusted for fine tuning* DO NOT TWIDDLE WITHOUT REASON

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 10
Problems Checklist:
The usual problems associated with a kerostart installation can
be narrowed to just two key items – the “Pump Start Point” and
the “Pump Power Ignition Kero”. Both of these can be trialled
with the same number and are adjusted to suit each fuel pump
fitted to the system.
A tight or new pump will benefit from some running-in before
fitting and this helps to settle the gears etc. The values may
need to be raised considerably to get the initial settings to get
the pump going. As the fuel pump loosens in service the values
for these functions may then need reducing by a few points to
make a start less aggressive.
We present here some of the usual things encountered in the
hope they clear up any problems you might see.
The checklists are listed in the order in which problems may be
encountered, ie setup and starting.
It is not intended in this supplement to cover normal running
problems as these would already be covered in the respective
operators manuals.
A detailed manual covering all the kerostart functions is
available to download from Xicoy Electronica SL on
www.xicoy.com
Be sure to ask for the V10 kerostart manual (there is a choice of
gas start too).
Symptom Problem Action
No reading on ECU
display unit
RX not switched on or RX
battery discharged
Verify connection and charge if
necessary
Display not connected
properly
Ensure that display is plugged in
the correct orientation
Display malfunction Contact Wren
ECU problem Contact Wren
Transmitter stick
down/trim up reads
“StickLo”
Throttle channel needs
reversing,
Reverse channel on Tx (most
Futaba’s need this)
Temp’ reading
incorrect or “0”
Thermocouple not connected
to ECU Verify connection
ECU problem Contact Wren
Thermocouple failure Contact Wren
Temp’ reading shows
lower or negative
figure on ignition
Thermocouple plug inserted
wrong way round
Ensure connector matches the
label on the ECU
No rpm indicated
when engine is spun
Rpm sensor plug inserted
incorrectly
Ensure connector matches the
label on the ECU
Rpm sensor lead
broken/chafed
Remove source of chafing and
repair/replace
Rpm sensor malfunction Contact Wren
ECU problem Contact Wren
Kerosene does not
ignite
Glow power set too low Check at least 6.8v in start
menu - Glowpower
Poor glow at igniter Check connections / earth
Plug partially blown Replace element
ECU battery low Charge
Burner fuel too low Increase burner fuel
(Pump Power Ignition Kero)
Burner valve not operating Check valve inserted
correctly into ecu
No kerosene ignition Pump not turning
Check pump for correct
operation (use “TEST/Prime
PUMP” in INFO)
ECU shows
“GlowBad” Element blown / open circuit Replace element (call Wren for service replacement)

Wren 44 Kerostart Supplement Copyright Wren Turbines Ltd 2012. All rights reser ed. Page 11
Problems Checklist – con’t We hope you have found this supplement helpful and that you
have enjoyed success in operation of your Wren 44 kerostart
engine.
Please note, all the items used in the
kerostart system are available as
individual spares – no need to buy a
whole new unit.
The ceramic burner element is
regarded as a long life component
but as with all electrical devices can
decide to give up without warning.
If the screw-in centre section of the kero igniter is returned to us
we can refit a new element for a small charge.
Alternatively you can buy an extra one for holding as a spare in
your flightbox so you never need to lose a flight due to an
expired element!
We are always pleased to get feedback from users and to take
additions to this supplement to enhance the experience of
others following the same pathway.
Please send us any comments or suggestions for inclusion to
[email protected].
Thank-you
Wren Turbines Ltd (UK)
Wren Turbines USA Feb 2012
Symptom
Problem
Action
Fuel pump not
running
Pump not connected Check wiring
Pump jammed with foreign
object
Investigate operation and
rectify (disconnect, run
backwards to clear)
No drive from ECU Contact Wren
No or little temp’ rise
on ignition
Insufficient burner fuel Increase Pump Power
Ignition Kero
Temp’ probe not inserted
into exhaust cone Insert 6mm
Pump runs but no
fuel delivered
Fuel not reaching tank pick-
up
Check clunk for blockage.
Ensure fuel like is not kinked
Pump fault Check solenoid operation
burner solenoid not opening Check wiring to ECU
No or little rpm
increase as fuel
enters
Insufficient revs on starter
motor Recharge ECU battery
Clutch slipping Replace O-ring
Air in fuel line Purge fuel lines and retry
Excessive flaming
Trim down/shut off fuel
immediately
Residual fuel in engine Spin engine “dry” for 5
seconds to clear
“Engine min flow” % too high Reduce 2 points and retry
Insufficient revs on starter Recharge ECU battery
Starter motor
weak/inoperative Contact Wren
“Pump Start Point “ too high Lower by 2 points and retry
Engine malfunction Return to dealer
Engine overshoots at
idle
Normal problem until ECU settles down
Aggressive starting Clear excess / lower Pump Start
Ramp by 2 points and retry
Air in fuel line causes late but
rapid start-up
ECU will correct itself and settle
down
Engine slows or is
stopped during start
Engine min flow set too low. Increase by 2 points and retry
Wild rpm reading
Interference to rpm pickup by
burner wiring (usually), find and
move. Check starter/burner
wires are well twisted.