The first part of the experiment read here.
In this part – let’s see what error messages have been recorded in the DME error message memory.
Some things remain the same – the problem of the “several” cylinders; the turbo aggregate is switched off.
The most interesting part – DME correctly identified the Combustion time problems in the correct (2nd) cylinder.
Let’s see these error messages closer:
The math of the allowed Combustion time difference between cylinders is not known, but we see – alarm has been raised in cases when the Combustion time of the damaged cylinder is around 4 times shorter than for correctly performing cylinders.
With too short Combustion time, everything is simple; its error threshold is 0.5 ms.
Everything looks correct. Surprisingly.
Tru thou, with the time stamp, is more interesting!
Misfires of the 2nd cylinder are noticed two times:
a. when during the CO catalytic converter warm-up phase, the engine starts to work on 5 cylinders;
b. in 3:02, when I performed the experiment exactly during the CO catalytic converter warm-up phase. Here is how it looks:
On the 23rd second after starting the engine, I started to drag out the ignition coil from its nest to imitate the misfires. The ignition coil was not taken out for so much for DME to register inappropriate combustion time (no error message regarding it was recorded – it is significant!). As we see, for some 10 seconds, the DME pretends to “not notice” anything, then suddenly starts to “notice” misfires.
Here is the continuation:
Speed of identifying the misfires: 5 .. 6 events/per second, which means DME again successfully identified ALL misfires!
And here for the contrast – misfire provoking started after the CO catalytic warm-up phase:
During 15 seconds, group misfires are provoked, and DME registers only THREE (the actual number of misfires – some 10 times more) of them!
Yes, I have not the slightest doubt – here, Bosch cheats again. During the CO catalytic converter warm-up phase, the crankshaft turning data are counted.
With the combustion time tolerance and absolute value error messages, everything is fine – they are registered exactly at the correct moments!
Conclusions after the experiment:
a. DME is correctly measuring combustion time and correctly registers the error messages regarding its inconsistencies;
b. as Bosch is not allowed to measure the changes in the turning speed of the crankshaft (and identify misfires by them), with the double effort “works” with the combustion time data. True, though, the tolerance error data corridor is extensive and almost coincides with the minimal combustion time. In this situation, the added value of the tolerance error is questionable;
c. during the CO catalytic converter warm-up phase, Bosch DME still “mystically” sees the misfires. It looks like cheating is going on here – in parallel to the combustion time and accelerometer data; however, the mechanical efficiency of the cylinders is checked, too;
d. by identifying the combustion time problem (also – the misfires during the CO catalytic converter warm-up phase), DME immediately correctly switches off the injector of the damaged cylinder.
It turns out that the fight of Bosch is quite desperate. Till this moment, the DME reaction was not a surprise to me, but – if there were no surprises, there would not be the 3rd part of this experiment. Read here.
