Name the moment before you name a map
A drivability complaint is a moment: the clutch biting, the first quarter of the pedal, a gearshift, a closed throttle, a cold start, a hot climb. A full-load pull in one gear does not contain most of those moments. Log the complaint itself, with the temperatures and the gear it happens in, and keep an original file so the calibration under the log is known.
Write four numbers in order. What the driver asked for. What the coordinators allowed. What the ECU estimated it delivered. What the air and the combustion actually did. The chain those numbers belong to is torque requests and the limit that wins.
Questions worth a channel
| Complaint | Keep these together | Read next |
|---|---|---|
| Smoke, or a hole, as the pedal opens | Pedal, requested and limited fuel or torque, air mass, requested and actual boost, engine speed | Diesel smoke limits, turbo response |
| Shunt, rock, or a sharp then loose pedal | Pedal, requested torque, engine speed, vehicle speed, gear | Pedal response and surge damping |
| Hunt, stall or roughness at idle | Idle target, measured speed, fuel or airflow used to hold it, coolant, electrical or air-conditioner load, per-cylinder correction | Idle speed and smooth running |
| Diesel knock, cold or at light load | Coolant, start of injection or spark, pilot quantity if it is logged, desired and actual rail pressure, glow status | Injection timing and combustion noise, cold start and warm-up |
| Soft only at part load, or only when hot | Fresh air mass, EGR command or position, boost, quantity, lambda, coolant | EGR and part-load behaviour |
| Stumble as the throttle reopens | Pedal, quantity or pulse width, lambda, boost, ignition or start of injection, through the cut and the return | Overrun and return to throttle |
| Fine yesterday, different today, no map change | Long-term fuel or quantity correction, boost adaptation, fault codes, the learning region | Adaptations and calibration drift |
| Pulls, then goes flat | The request before and after the flat spot, temperatures, gear, a traction or gearbox intervention, a regeneration mode if one is active | Which limit wins |
Use the family's channels, not a borrowed list
The column above is the question. The channel names belong to the ECU. ME7's logging page separates requests, limits, models, measurements and outputs. EDC15 and EDC16 diagnostic pages show example quantity, smoke and torque parameters that are not universal. Simos and MG1 pages list the channels their own sources expose. Copying an address or a label across those pages is how a log starts describing the wrong quantity.
Record the software identity, the logger definition and the units with the file. A milligram-per-stroke channel and a newton-metre channel can both be called torque by the person reading the screen. Absolute pressure and gauge pressure differ by ambient. Requested, limited and estimated torque are three traces.
One change, then the same log again
ME7's getting-started sequence is the right shape for any of these complaints: identify the software, log a healthy baseline, understand which model is active, change one system, and repeat the same test. ME7 getting started. A higher requested number that the engine does not deliver means some other limit, or the hardware, is still in the way. ECU remapping states that boundary for the calibration as a whole.
Sources
- Torque requests and the limit that wins and the drivability pages linked from the table. Each of those cites the Bosch EDC description or the family page the complaint belongs to.
- ME7 getting started and ME7 logging. The baseline-and-one-change method, and the split between request, limit and measurement.