ISTA as if offers Misfire counters in the data list of the Diagnosis scan:
Unfortunately, after driving session these data always show 0.00. I checked several versions of ISTA on DME, which were updated at the end of the Year 2019. As ISTA returns some (0.00) results not “not available” (which could mean job error) – I assumed that the reporting of these counters is not included in the software of DME itself. But no, actually, these are misfire identificators, not counters. Misfires are identified (corresponding register shows 1.00; 2.00, etc.), but after 3 ..5 seconds value of these registers is cleared.
Good news: also, these DME reports the error messages via OBD Mode 6. Accordingly, they could be read by the ELM327 type adapter and the appropriate software.
Pay attention: this DME initially reports midsession (long-term) counters of each cylinder, only after – the misfire counters of the actual session. This is the opposite as used by Siemens DME.
The math of the misfire counters – “the old one”, corresponds to the one described here.
Features I observed in this DME:
a. even by the large density of misfires (see the picture above), no error messages were recorded in DME;
b. these DME measures the time of each ignition (as also the Siemens, starting from MSD85), accordingly – (by the idea) they can identify misfires even when the required torque is low or very low, and the fluctuations (shivering) of the flywheel is barely noticeable (and cannot be used as sensing data). In addition, identification of the misfires by the fluctuation of the flywheel – patent of Siemens. Bosch, instead, has patented the misfire identification by the accelerometer data, which is not an effective method in conditions of low required torque;
c. it looks, then in the case of worn spark plugs, the misfires for these engines are starting exactly on low/average RPM + low/very low required torque. These misfires are not very pronounced (the required torque is small, and the cylinders’ mechanical energy is not large). Obviously, this mode is the worst mixing of the fuel and air due to very weak airflow (the inlet valves are almost closed, which is ensured by the Valvetronic). In addition, to prevent knocking (these engines have high compression: 1:11), the fuel is injected directly before ignition – it has no time to mix with the air, and the mixture is far from Homogeneous.
Regarding nuances of misfire indications for these DME, read here.
