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, Thu, 26 Aug 2010 11:02:34
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Cars concerned
Saab 900 B234i with Motronic 4.1 OBDII M96-98
Background
Some states, as part of their mandatory State Emission
Testing program, will include checks for OBD
readiness codes. Some M96-98 naturally-aspirated
2.3L 900’s may fail these checks, especially if the
battery has lost power or if DTC’s have been reset
using Tech2.
The following information will allow a technician,
using a Tech2 to perform a specific driving cycle that
will allow the Motronic M4.1 system to set the
required readiness codes.
Symptom description
Failed checks for OBD readiness codes
Actions
Preparation before driving:
Before driving, make sure that there are no DTCs
stored in the ECU of Motronic 4.1. If codes are
stored, repair the affected system and clear the fault
codes. M96 models with Secondary Air Injection
(SAI) must begin each driving cycle with engine
temperature below 40°C (104°F), so car must cool
down between driving cycles. All other models may
begin with engine at normal running temperature.
Connect Tech2 and read out the following values
under Motronic M4.1- OBD II - Read Values - Activate
and scroll down to Diagnostic Status. The following
functions are important:
• Evap
• Catalytic Converter
• Oxygen Sensor
• Preheating
• Secondary Air (only M -96)
• Trip OBD II
Further down in the same menu you can read out
rpm and engine load in "ms". The load and rpm must
be kept between 1.3 - 4.3 ms / 1120 -2500 rpm for
automatic cars and 1.3 - 3.8 ms / 1320 -2700 rpm for
manual cars to fulfill the requirements and set the
readiness flags.
While you are driving it is OK to stop, slow down or
speed up. Once you have met the requirements of a
particular segment for load and rpm, a time counter
will start and accumulate elapsed time. If you stop,
the counter will resume accumulating time when you
are back at the correct load and rpm again. One
"Trip" takes 20 minutes of driving at the correct load
and rpm. To set all of the readiness flags, it takes
two "Trips" (2 x 20 minutes). It is OK to drive with
the A/C on, however the cycling of the compressor
will make it more difficult to keep a steady load.
Due to different final drive ratios/tire sizes, speeds
listed may not match the given RPM reading. In
these cases, the RPM range should be followed.
How to drive: Automatic cars
Before driving, make sure to read and understand
the steps of the procedure.
1 Start the car and check the time. Drive 0 -70
mph for 3 -5 minutes. Check using Tech2 that
preheating 1 & 2 and oxygen sensor 1 & 2 are
"Ready". If not, drive until they are "Ready".
2 Drive at 35-40 mph in Drive position (D) for 5
minutes. Drive with as steady load as possible.
Load and rpm should be within 1.35 - 2.3 ms and
1120 - 1500 rpm.
3 Increase the speed to 40 - 50 mph for 5 minutes.
Load and rpm should be within 1.3 - 2.3 ms and
1520 - 2000 rpm.
4 Increase the speed again to 55 - 60 mph in Drive
position and drive for 5 minutes with a steady
load. Load and rpm should be within 2.3 - 4.3 ms
and 2000 -2500 rpm.
5 Park the car and shut off the A/C and let the
engine idle for up to 10 minutes. Check the values
in Tech2. Trip OBD II must say "Ready".
6 When you have got "Ready" for Trip OBD II,
shut the engine off for one minute and start it
again. Repeat steps 1 - 5.
7 Read out if readiness is OK with Tech2. Go to
GST (Generic Scan Tool), then go to Powertrain
Control Module (PCM) and Read Values to see
if readiness is OK.
Following functions should be set "Ready":
• Catalyst
• Heated Catalyst
• EVAP
• Secondary Air Injection (Only model year
1996)
• O2-sensor
• HO2-sensor
If you fail (no flags are set to "Ready") repeat the
procedure above again.
Focus on driving with as steady load as possible.
The whole procedure takes about 60 minutes.
How to drive: Manual cars
Before driving, make sure to read and understand
the steps of the procedure.
1 Start the car and check the time. Drive 0 -70
mph for 3 -5 minutes. Check using Tech2 that
preheating 1 & 2 and oxygen sensor 1 & 2 are
ready. If not, drive until they are "Ready".
2 Drive at 35-40 mph in 4:th gear for 5 minutes.
Drive with as steady load as possible. Load and
rpm should be within 1.35 - 1.95 ms and 1320 -
2000 rpm.
3 Increase the speed to 40 - 50 mph. Use 4:th
gear for 5 minutes. Load and rpm should be
within 1.3 - 1.95 ms and 2000 - 2700 rpm.
4 Increase the speed again to 55 - 60 mph with
5:th gear and drive for 5 minutes with a steady
load. Load and rpm should be within 1.95 - 3.7
ms and 2000 -2700 rpm.
5 Park the car and shut off the A/C and let it idle
for up to 10 minutes. Check the values in Tech
2. Trip OBD II must say " Ready".
6 When you have "Ready" for Trip OBD II, shut
the engine off for one minute and start it again.
Repeat steps 1 - 5.
7 Read out if readiness is OK with Tech2. Go to
GST (Generic Scan Tool). Then go to Powertrain
Control Module (PCM) and Read Values to
check if readiness is OK.
Following functions should be set "Ready":
• Catalyst
• Heated Catalyst
• EVAP
• Secondary Air Injection (Only valid for M96,
all other models will automatically show
"Ready")
• O2-sensor
• HO2-sensor
If you fail (no flags are set to "Ready") repeat the
procedure above again. Focus on driving with as
steady load as possible. The whole procedure
should take about 60 minutes.
Note
We have seen that catalytic converter does not set
"ready". This is a fault in Tech2.
Note
M96 models with SAI must be allowed to cool
down between trips.
Note
If the PCM looses power by, for example, disconnecting
the battery, removing fuses which feed the
PCM, disconnecting the PCM or if DTCs are deleted
you will loose the readiness OKs and you are
back to zero again and must repeat the complete
driving cycles.
Note
For 1996 models only, because of the Secondary
Air Injection (SAI) it is necessary to start with a
cold engine (below 40°C/104°F) to set the SAI
readiness codes.
Note
posted by 71.110.5...
, Thu, 26 Aug 2010 11:02:34
, Thu, 26 Aug 2010 21:27:05
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