1999-2009 [Subscribe to Daily Digest] |
It's a pretty easy job. Just need a T30 torx for the IDM screws and a spark plug socket.
Most the time the faults are p1312 and p1334.
These are combustion detection faults. Even though they are important to the operation of the ignition system, for some reason most the cars with these codes have no running problems. The fault may be so intermittent that it never creates a running problem issue.
Here's the description of how the combustion detection works,
Trionic T7 does not have a camshaft sensor, which is normally a condition for sequential knock control and fuel injection.
On starting, the control module is not aware of which of the cylinders 1 or 4 that is in compression position. Consequently, ignition takes place in both cylinder 1 and 4 simultaneously. Ignition in cylinders 2 and 3 takes place in the same way.
The control module must determine whether combustion has occurred in cylinders 1 and 4 or in cylinders 2 and 3 when they are triggered.
This is achieved in the following way:
One of the poles on the secondary windings of the 4 ignition coils is connected to the respective spark plug as normal. The other pole is not grounded directly but is connected to 80V. This means that 80V is always present across the spark plug gap except just as the spark is produced.
When combustion has taken place, the temperature in the combustion chamber is extremely high. The gases ionize and start to conduct current. This means that a current passes across the spark plug gap without producing a spark.
Once the circuit across the spark plug gap has been completed, the 80V will drop sharply. The drop in voltage will be proportional to the pressure and temperature in the combustion chamber.
Two detectors measure the voltage drop across the cylinder pairs 1+2 and 3+4 respectively. If combustion takes place in cylinder 1 or 2, the ignition discharge module will send a B+ pulse to control module pin 53. In the same way, the ignition discharge module will send a B+ pulse to control module 6 if combustion takes place in cylinder 3 or 4.
If cylinder 1 and 4 are triggered and a B+ pulse is received on control module pin 53 at the same time, the control module will be made aware that cylinder 1 has fired.
As soon as the combustion signals arrive at control module pin 53 or 6, both ignition and fuel injection are synchronized to the engine firing order.
The combustion signals are also used to detect misfiring.
Combustion signals
If there is an open circuit on both leads to control module pins 53 and 6, the ignition and injection will not be synchronized. Knock detection will then take place in parallel on cylinders 1+4 and cylinders 2+3.
• If there is an open circuit to control module pin 53, diagnostic trouble code P1312 will be generated.
• If there is an open circuit to control module pin 6, diagnostic trouble code P1334 will be generated.
• If the ignition cannot be synchronized to the camshaft position, diagnostic trouble code P0340 will be generated.
posted by 71.110.5...
, Tue, 28 Oct 2008 19:59:24
, Wed, 29 Oct 2008 21:08:58, Wed, 29 Oct 2008 21:10:26
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
