Technical Information · issue 49 of 2006
Intelligent Engine Management; Diagnosis; Servicing; Summary; Special tool
IssueTI 49/2006
Engine family 1133
Full text
Page 1 of 17
STIH)
Technical Information 49.2006
Chain saw STIHL MS 280 – Series 1133
Contents
1. Intelligent Engine Management
2. Diagnosis
3. Servicing
4. Summary
5. Special tool
1. Intelligent Engine Management
Chain saws MS 280 and MS 280 C will be equipped
with Intelligent Engine Management in the future.
TI_49_2006_30_01_01.fm englisch / English USA
)m~ge 2 Technical Information 49.2006
On these chain saws the full load mix and maximum 1.1.2 Ignition module
engine speed will be electronically controlled. The ignition module has an integral microprocessor
Intelligent Engine Management is designed to to monitor the engine speed and regulate the
provide optimum engine power, very good solenoid valve.
acceleration, a constant maximum speed and Spare parts/Service note
automatic adaptation to conditions (e.g. at high
altitudes), without manual adjustments. The new ignition module can be identified by the
impressed designation. See 3.1.1. Ignition
Machines with Intelligent Engine Management are module/flywheel combination.
identifiable by the carburetor box cover. These
machines do not have the high speed screw H or,
consequently, the hole in the carburetor box cover to
allow adjustment.
1.1 Components
1.1.1 Carburetor/solenoid valve
The high speed screw H is replaced by the solenoid
valve (1). The fuel delivery is controlled by the
electronically switched solenoid valve.
The solenoid valve operates digitally. It opens and
closes 30 times per second. The “opening” and
“closing” times are variable, i.e. the fuel flow can be
controlled by the valve.
Idle mixture adjustments can be made by means of
the low speed screw L as previously.
The carburetor does not have a compensator.
The compensator function, that is, keeping the mix
proportions constant irrespective of how dirty the air
filter is, is performed by the regulating system in the
ignition module and solenoid valve.
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Technical Information 49.2006 Page 3
1.1.3 Flywheel 1.1.5 Filter base
Intelligent Engine Management provides constant
mixing, irrespective of how dirty the air filter is.
The compensator connections are therefore not
provided on the filter base or on the carburetor.
Supply of spare parts
The previous filter base will continue to be available
for machines without Intelligent Engine
Management.
1.1.6 Carburetor box cover
A second pair of poles on the flywheel provides the The carburetor box cover no longer has the hole for
necessary power supply for the microprocessor and adjustment of the high speed screw H. With
the solenoid valve. Intelligent Engine Management the high speed
screw is replaced by the solenoid valve.
Supply of spare parts
Supply of spare parts
The previous flywheel will continue to be available
for machines without Intelligent Engine The previous carburetor box cover will continue to
Management. be available for machines without Intelligent Engine
Management.
1.1.4 Wiring harness
The connection between the ignition module and
the solenoid valve is made by means of two wires
switched in parallel to the ground wire or short circuit
wire.
Spare parts/Service note
The previous wiring harness, without a terminal for
the solenoid valve, will continue to be available for
machines without Intelligent Engine Management.
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1.2 Function The next regulating cycle will start again with the
The microprocessor in the ignition module monitors solenoid valve closing briefly. A regulating cycle only
the engine speed and regulates the solenoid valve. starts if the engine is operated for approximately
5 seconds under constant conditions.
The speed change due to the brief leaning of the mix
is so slight as to be imperceptible to the user.
1.3 Advantages
. Optimum engine performance at all times
. Very good acceleration
. Constant maximum speed
. Automatic adaptation to altered conditions of
use e.g. when working at a high altitude
If the solenoid valve (1) is open for a large part of the
time within the 30 millisecond switching cycle, the 2. Diagnosis
fuel flow is increased.
The flow charts that follow deal with specific parts
If, on the other hand, the solenoid valve is open for diagnosis and trouble-shooting for Intelligent Engine
a smaller part of the time, the fuel flow is reduced. Management.
The flow charts help you to take the correct step at
the correct time. All other diagnosis and repair
If the engine is in use under constant conditions for
operations remain unchanged.
approximately 5 seconds the solenoid valve closes
briefly (approx. 1/10 second) and the fuel flow is
reduced. The current fuel/air mix becomes leaner.
The resulting engine speed pattern is analysed by
the microprocessor.
The following results are possible:
Engine speed increases
The mix was too rich before the solenoid valve
closed – the fuel flow is reduced for next phase of
operation.
Engine speed decreases
The mix was too lean before the solenoid valve
closed – the fuel flow is increased for the next phase
of operation.
Engine speed does not change
The current carburetor setting is optimal – the
current setting will be maintained.
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)======qechnical Information 49.2006 Page 5
2.1 Carburetor
Poor acceleration
Check the air filter. Clean or replace if necessary.
Set low speed screw (L) to standard setting
(Rotate low speed screw clockwise – as far as the stop – then
back 1/4 turn)
Low speed setting too lean? Low speed setting too rich?
– Rotate low speed screw counterclockwise (richer) – Rotate low speed screw clockwise (leaner)
– no further than stop – no further than stop
Open the throttle fully for at least 10 seconds –
maximum engine speed
Run under load (engine speed approx. 10,000 rpm, approx.
12 in. log diameter) –
Alternatively to running under load, operate the chain saw with
the bar and chain for approximately 10 seconds at 10,000 rpm
yes no
Chain saw OK?
Check operation $ / # via Look for a fault in the fuel path,
the master control check engine for air leaks
End
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)m~ge 6 Technical Information 49.2006
Engine speed drops quickly under load –
low power
Check the air filter and clean or replace if necessary
Open the throttle fully for at least 10 seconds –
maximum engine speed
Carry out five uniform cuts under load
(speed approx. 10,000 rpm, approx. 12 in. log diameter)
Alternatively to cutting under load,
operate the chain saw with the bar and chain for approximately
30 seconds at 10,000 rpm
yes no
Chain saw OK?
Check operation $ / # via Look for a fault in the fuel path,
the master control check engine for air leaks
End
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Technical Information 49.2006 Page 7
Maximum permitted speed not reached
Check the air filter and clean or replace if necessary
Open the throttle fully for at least 10 seconds –
maximum engine speed
Carry out about five cuts under load
(engine speed approx. 10,000 rpm, log diameter
approx. 12 in) –
Alternatively to cutting under load, operate the chain saw with the
bar and chain for approximately 30 seconds at 10,000 rpm
no1)
Maximum speed OK?
(14,000 rpm)
yes
Check operation $ / # via
the master control
End
1) If maximum speed is not reached, check the fuel path and engine
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2.2 Ignition System
No spark
Check the ignition module/flywheel combination and correct if
necessary
(see 3.1.1 Ignition module/flywheel combination)
yes no
Chain saw OK?
Check operation $ / # via Check the ignition module in
the master control accordance with the “Ignition module
fault location” sequence, see
Servicing Notes
End
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Technical Information 49.2006 Page 9
At speeds over 4,000 rpm the ignition module switches off
after approx. 10 seconds
Check resistance between open short circuit wire
and ground wire
(see 3.2.1 Solenoid valve:
Check resistance when fitted in place)
yes
Resistance between
30 ... 38 Ohms?
Resistance is zero nil – short circuit Resistance is infinite –
Check the wiring harness, plug connection and wiring harness damaged (break in wire)
solenoid valve Replace wiring harness if necessary
Replace wiring harness and/or
solenoid valve if necessary Check operation of plug connection on
solenoid valve
and check solenoid valve
Replace solenoid valve if necessary
yes no
Chain saw OK?
Check operation $ / # via Replace ignition module
the master control
End
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3. Servicing 3.1.2 Calibrating the ignition module
A new ignition module can be calibrated after fitting
3.1 Ignition system to ensure an optimum setting
. Start the chain saw – the chain and guide bar
3.1.1 Ignition module/flywheel combination
must be mounted
The correct ignition module/flywheel combination is
essential to allow Intelligent Engine Management to . Open the throttle fully for at least 10 seconds –
operate correctly. The flywheel must be equipped maximum speed
with two pairs of poles. The associated ignition . Allow the chain saw to idle for at least
module is identifiable by the designation 10 seconds
MS 280 C A or MS 280 # on the housing:
. Then open the throttle fully again and maintain
maximum speed for at least 10 seconds
. Allow the chain saw to idle again for at least
10 seconds
Do not switch off the chain saw during calibration.
If calibation does not take place correctly, after a few
minutes of saw operation during which several
regulating sequences occur, the microprocessor will
reach its optimum setting.
146TI055 KN
Identification Part No. Chain saw
MS 280 C A
MS 280,
or 1133 400 1353
MS 280 C
MS 280 #
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Technical Information 49.2006 Page 11
3.1.3 Engine stops – ignition module switches 3.2 Carburetor
off
The microprocessor continually checks the 3.2.1 Solenoid valve: Checking resistance
connection between the ignition module and the when fitted in place
solenoid valve (resistance test). If the test does not
produce a positive result within 10 seconds at a
speed over 4,000 rpm, the microprocessor switches
off the ignition system and the engine stops.
If the connection with the solenoid valve were to be
severed, the solenoid valve would remain open all
the time. Too much fuel would enter the cylinder and
the fuel/air mix would be too rich. To prevent this, the
microprocessor switches off the ignition system.
Checking operation
Insert the ignition system tester ZAT 4
(5910 850 4503) between the spark plug boot and
the spark plug.
. Remove the carburetor box cover
. Detach the air filter
. Set the master control to k = cold starting
setting
. Set the meter to the range Ω
000TI036 KN
1 2 3 . Attach test lead (1) to the contact spring and test
lead (2) to the eyelet of the short circuit wire
. Remove the spark plug boot from the spark plug . The resistance should be 30 …. 38 Ω
and push it on to the input terminal (1). Push the
output terminal (3) on to the spark plug.
Resistance is infinite
. Start the chain saw and check the spark jump in
. The wiring harness is damaged (broken cable):
the viewing window (2).
replace wiring harness if necessary
. If the ignition spark fails after about 10 seconds
. Check the plug-in contact on the solenoid valve
at a speed over 4,000 rpm, check the electrical
and replace the solenoid valve if necessary (see
connection between the ignition module and the
3.2.2 Solenoid valve: Checking the resistance
solenoid valve (see 3.2.1 Solenoid valve:
when dismantled)
Checking resistance when fitted in place)
No resistance (0 Ohm)
. Short circuit – check the wiring harness and
plug-in contacts and replace the wiring harness
if necessary
. Checking the solenoid valve when dismantled
(see 3.2.2 Solenoid valve: Checking the
resistance when dismantled and 3.2.4 Solenoid
valve: Checking the switching function when
dismantled)
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3.2.2 Solenoid valve: Checking the resistance 3.2.3 Solenoid valve: Checking the switching
when dismantled function when fitted in place
. Remove the carburetor box cover . Remove the carburetor box cover
. Detach the air filter . Detach the air filter
. Unscrew the collar nuts and detach the baffle . Set the master control to k = cold starting
and filter base setting
. Unscrew screw (1) and pull off the solenoid . Apply a 9 V test voltage between the contact
valve spring (1) and the eyelet (2) of the short circuit
wire
. When the circuit is made, the solenoid valve
should click (switch). Always make the circuit
only briefly, to avoid damaging the solenoid
valve.
. If the solenoid valve fails to switch, dismantle
and check the solenoid valve
. Set the meter to measuring range Ω
. Use a “spare” wiring harness for the purpose of
testing
. Push the plug (1) on to the solenoid valve (2)
. Attach test lead (3) to the socket and test
lead (4) to the eyelet of the short circuit wire
. The resistance should be approx. 30 …. 38 Ω –
replace the solenoid valve if necessary
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Technical Information 49.2006 Page 13
3.2.4 Solenoid valve: Checking the switching 3.2.7 Limiter cap on the low speed screw (L)
function when dismantled The limiter cap has to be removed in order to clean
. Dismantle the solenoid valve – see “Solenoid the carburetor.
valve: Checking the resistance when
dismantled”
. Screw the puller 5910 890 4500 (special tool)
counterclockwise (left-hand thread) about five
Use a “spare” wiring harness for the purpose of turns into the limiter cap
testing.
. Push the plug (1) on to the solenoid valve (2)
. Apply a 9 V test voltage between the socket (3)
and the eyelet (4) of the short circuit wire
. When the circuit is made, the solenoid valve
should click (switch). Always make the circuit
only briefly, to avoid damaging the solenoid
valve.
. If the solenoid valve fails to click (switch) –
replace the solenoid valve
3.2.5 Solenoid valve dirty
The sections of the fuel ducts in the solenoid valve . Turn the limiter cap of the low speed adjustment
are bigger than in the carburetor. The likelihood of screw L clockwise, using the puller – as far as
the solenoid valve failing due to dirt is therefore very the limiter cap stop – then turn the limiter cap
low. The solenoid valve cannot be disassembled 1/4 turn back, so that the screw slot (1) of the
without damaging it and should therefore be limiter cap lines up with the slot (2) in the
replaced. carburetor housing – the lug on the limiter cap
must be visible through the slot in the insert in
3.2.6 Installing the solenoid valve the carburetor housing
. Check the seal for damage and replace if
necessary
. Insert the solenoid valve into the carburetor
housing, turning it gently to and fro as you do so.
The collar on the valve housing should lie snug
with the carburetor housing.
. Screw in the round head screw and tighten
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Adjust the specified engine speeds within a
tolerance range of +/- 200 rpm as follows:
1. Use the idle speed screw (LA) to set the
engine speed to 3,300 rpm
2. Rotate the low speed screw (L) clockwise or
counterclockwise to obtain maximum engine
speed
. Remove the limiter cap If this engine speed is higher than 3,700 rpm, abort
the adjustment and start again from the beginning
(step 1)
Basic setting without limiter caps
3. Use the idle speed screw (LA) to set the
. Check air filter – clean or replace it if necessary.
engine speed to 3,300 rpm once again
The basic carburetor setting can be made more
easily by fitting the setting disc 5910 893 6600 4. Use the low speed screw (L) to set the
(special tool) on the carburetor screwdriver. engine speed to 2,800 rpm.
5. Then go on as described under “Securing the
Limiter Cap”
Securing the Limiter Cap
. Starting from the tight position of the adjusting
screw:
Open L = 11/4 turns
Do not re-install the used cap, since it is damaged
during removal.
. Fit the new limiter cap into the hole as shown,
making sure the lug is correctly positioned (see
arrow)
. Push the limiter cap on to the adjusting screw
until it is flush with the base of the slot
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Technical Information 49.2006 Page 15
3.2.8 Carburetor setting instructions for the Speed erratic when idling; poor acceleration
user
. Adjust the low speed screw (L) to the standard
Standard setting setting
. Switch off engine . Turn the low speed screw (L) counterclockwise
. Check the air filter – clean or replace it if until the engine runs and accelerates smoothly
necessary. – but no further than the stop
. Check the spark arresting screen in the muffler . Open the throttle fully for approx. 10 seconds,
(if fitted) and clean or replace as necessary. with the chain and guide bar fitted.
. Check fuel filter and replace if necessary . Carry out a cut under full load.
. Rotate the low speed screw (L) clockwise as far
as the stop. Then turn back 1/4 turn. It is usually necessary to change the setting of the
idle speed screw (LA) after every correction to the
low speed screw (L).
Setting the idle speed
. Engine stops when idling Operation in different conditions
. Adjust the low speed screw (L) to the standard The full load mix and maximum engine speed adjust
setting. automatically to different conditions (e.g. working at
. Turn the idle speed screw (LA) clockwise until high altitude).
the chain begins to run, then turn the screw back The automatic adaptation of the optimal engine
one turn. power can be speeded up as follows:
. Open the throttle fully for approx. 10 seconds,
Saw chain rotates at idle speed with the chain and guide bar fitted.
. Adjust the low speed screw (L) to the standard . Carry out five uniform cuts under full load.
setting
. Turn the idle speed screw (LA)
counterclockwise until the chain stops running –
then turn another turn in the same direction.
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4. Summary
7 5
6
146TI054 KN
Item Part name Previous New Remarks
1 Carburetor HD-39 1133 120 0607 1133 120 0612 1)
2 Solenoid valve --- 0000 120 5100
3 Filter base 1133 124 3400 1133 124 3401 1)
4 Carburetor box cover 1133 140 1900 1133 140 1902 1)
5 Ignition module 1133 400 1350 1133 400 1353 1)
6 Flywheel 1133 400 1204 1133 400 1203 1)
7 Wiring harness 1133 440 3001 1133 440 3002 1)
Modification to be introduced continuously
Remarks
1) Previous version of part remains available as spare for machines without Intelligent Engine Management
and other series.
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Technical Information 49.2006 Page 17
5. Special tool 5.2 Wiring harness 1133 440 3002
5.1 Tachometer
The spare “wiring harness” 1133 440 3002 should
be used to test the solenoid valve.
The new tachometer STIHL EDT 8 (5910 850 1009) The wiring harness ensures a precise connection
or STIHL EDT 7 (5910 850 1008) is required in with the solenoid valve. Simply apply the test leads
order to measure the engine speed on chain saws to the terminal socket (1) and the eyelet (2). To
with Intelligent Engine Management (see prevent errors in measurement, isolate the terminal
TI 10.2006). socket (3) on the ground wire.
The previous tachometers EDT 5 and EDT 6 cannot
be used, due to the additional pulse from the second
pair of flywheel magnet poles on these chain saws.
The additional pulses cause errors in measurement.
The test lead should be used to record the pulses for
the purpose of speed measurement. Attach the test
lead terminal to any part of the ignition lead or the
spark plug boot.
© ANDREAS STIHL AG & Co. KG, 2006 Technical Documentation
D1/MTK-bl
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Extracted from the manufacturer's 2012 service catalogue. Most of these PDFs embed fonts with a shifted character map, so the text above was recovered rather than copied — read it as a faithful but imperfect transcription, and treat the page image above each block as the authority where the two disagree — the figures exist only there, because they are vector drawings that text extraction cannot keep.