Thread: Rough Running - Nanocom Evo, D2 V8

After having new catalytic convertors fitted recently misfires developed on two cylinders. I also noted that when running the Nanocom diagnostics there were indications of rough running .
I surmised that the misfires were most probably due to breakdown of either/both plug leads or coils.
Fitted new coils, new plugs & leads, and also new fuel injectors as I suspected that the injectors may have been responsible for the rough running indications. However, after the changes I am still seeing rough running on a couple of cylinders.
Any suggestions as to cause & remedy?

I asked about the loop settings as knock detection (again at last on D2 V8's) is disabled in cold start mode which is also fixed to closed (???) loop mode, so you will see more roughness in the nanocom until it warms up.

Try unplugging the knock sensors (warm) to see if it changes the Nanocom readings (it shouldn't, it should become worse).

From the Bosch SM009/BBS website. There's a couple of things detailed that should help to point at the crank sensor etc to better check function (over just a code).

ROUGHNESS AND TIMING
Roughness cylinder 1 to 8: This display shows the current value which the ECU has calculated for the engine running roughness for each cylinder. This value will increase the more unevenly the engine is running. Engine roughness is not displayed if idle.
Cylinder misfire 1 to 8: Count of misfire events for each cylinder. When the ECU detects a possible misfire, this count value is increased by one. If the value increases to more than a preset limit within 1000 engine revolutions, a misfire fault is set. If not, the misfire count value will be cleared to 0 and a new count begin. It is normal to expect a certain number of 'false' misfire detections during each count.
Ignition advance cylinder 1 to 8: This value shows the ignition timing for each cylinder. The individual cylinder ignition timings should not differ from each other significantly for any sustained period.
Ignition advance: This reading shows the average ignition advance over all cylinders and it is affected by engine speed, engine load, change of gear, knock detection, throttle position and coolant temperature. During idle condition this value may continuously vary as the ignition advance is used to stabilise the idle speed.
Dwell angle: This reading shows the current value of the ignition dwell angle (the amount of rotation of the engine during which an ignition coil is charging. Since the charging time tends to be constant (it only varies with battery voltage) the reading will increase in proportion to engine speed. An unusually large reading may indicate a problem with battery voltage.
Tooth count: This display shows the number of crankshaft sensor wheel edges counted by the ECU. This value will count up extremely rapidly during engine running but can be useful for checking that the crankshaft sensor is correctly connected during cranking. If the engine is cranked this display should count up at a rate of at least 30 counts per second. If this does not happen there may be a problem with the crankshaft sensor or crankshaft sensor circuit.
Misfire sum: Summary of misfire events over all cylinders. When the ECU detects a possible misfire, this count value is increased by one. If the value increases to more than a preset limit within 1000 engine revolutions, a misfire fault is set. If not the misfire count value will be cleared to 0 and a new count begun. It is normal to expect a small number of 'false' misfire detections during each count.
Knock average: This reading shows an average value for knock correction. If this value is continuously above 0, it may indicate a problem with the knock detection system or the engine.
Knock detect: This reading shows whether the ECU is currently operating its knock control strategy by changing the ignition timing and/or fuelling for of one or cylinders.