Some after tune data logging with Bimmerlink and analyses by ChatGPT, makes it so easy to summarize more than 10000 data points.
Some things to note, I think the IAT is an absolute figure so you need to add about 23 Degrees ambient. The manifold EGT is a calculated figure since the B57 only has a pre and post cat temp sensor, both being post turbo temp measurements.
Lambda figures also need to be calculated since Bimmerlink does not give a figure for it.
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Here’s an analysis of your two logged runs after the tune and EGR delete on your
BMW G20 330d.
I'll compare the two logs side by side and focus on the critical parameters you asked about:
lambda (AFR), EGT,
intake temp,
injection,
air mass flow, and
boost levels.
1. Engine Speed & Driving Behavior
| Metric | Log 1 | Log 2 |
|---|
| RPM Max | 3,656 | 4,450 |
| RPM Median | 2,523 | 2,924 |
| Pedal Max % | 87% | 100% |
Interpretation:
- Log 2 had a fuller WOT pull up to 4,450 RPM.
- Log 1 is a slightly lighter pull, peaking at ~87% pedal.
2. Intake Air Temperature (IAT)
| Metric | Log 1 | Log 2 |
|---|
| Avg IAT (°C) | 30.0 | 24.4 |
| Max IAT (°C) | 32.0 | 25.0 |
Interpretation:
- Log 2 was run in cooler ambient conditions, giving denser air and slightly better performance potential.
- IATs stayed well below 40°C, which is excellent.
- No heat soak issues observed.
3. Exhaust Gas Temperatures (EGT)
| Location | Log 1 | Log 2 |
|---|
| Manifold (calculated) max | 1,065°C | 1,100°C |
| Pre-cat measured max | 523°C | 649°C |
Interpretation:
- Manifold EGTs are high but within diesel tuning safety limits (<1,150°C).
- Pre-cat measured EGTs rose significantly higher in Log 2, which correlates with the harder WOT pull.
- After EGR delete, expect slightly higher EGT due to more oxygen and complete combustion, but these values are safe.
Recommendation:
Monitor EGT closely during prolonged WOT or towing. Sustained >750°C pre-cat could be harmful for the turbo and DPF.
4. Boost Pressure
| Metric | Log 1 | Log 2 |
|---|
| Boost Peak (bar) | 1.81 | 1.82 |
| Boost Target Peak (bar) | 1.85 | 1.84 |
Interpretation:
- Both logs track very close to target, indicating the tune has good boost control.
- No signs of overboost or large deviations.
- This is typical for a Stage 1 tune on the B57 engine.
5. Fuel Injection Quantity
| Metric | Log 1 | Log 2 |
|---|
| Injection Peak (mg/stroke) | 86.57 | 88.22 |
| Desired Peak (mg/stroke) | 83.07 | 84.69 |
Interpretation:
- Your tune is running a moderate increase in injection quantity compared to stock (typically 65–75 mg/stroke stock).
- The engine is closely following target, showing no major rail pressure limitations.
6. Air Mass Flow
| Metric | Log 1 | Log 2 |
|---|
| Air Mass / Cylinder Peak (mg/stroke) | 1,533.85 | 1,555.68 |
| Charge Mass Flow Peak (kg/h) | 756.47 | 813.53 |
Interpretation:
- Airflow is healthy and consistent with Stage 1 tuning.
- Slightly higher peak flow in Log 2 due to the colder air and higher RPM pull.
7. Lambda (AFR) Discussion
Unfortunately,
lambda values were not logged, but we can infer indirectly:
- With a max injection of ~88 mg/stroke and peak air mass around 1,550 mg/stroke:
AFR=AirMassFuelMass=155088≈17.6AFR = \frac{Air Mass}{Fuel Mass} = \frac{1550}{88} ≈ 17.6
- Stock AFR at WOT is around 17–18:1 for the B57.
- Your inferred AFR of ~17.5:1 is safe and consistent with Stage 1 tuning.
Signs of healthy AFR:
- Minimal black smoke (you reported some at WOT — this is normal with EGR delete).
- Good rail pressure tracking.
Summary Table
| Parameter | Observation | Status |
|---|
| IAT | 24–32°C, stable | ✅ Good |
| Pre-cat EGT | Up to 649°C | ✅ Safe |
| Manifold EGT | Up to 1,100°C | ✅ High but safe |
| Boost | Stable, 1.82 bar peak | ✅ Excellent |
| Injection Qty | 88 mg/stroke peak | ✅ Normal for Stage 1 |
| Airflow | 1,550 mg/stroke peak | ✅ Healthy |
| Lambda (AFR) | ~17.5:1 inferred | ✅ Ideal |
Overall Assessment
Your tune and EGR delete look
safe and well-controlled:
- EGTs are slightly higher but expected due to EGR delete.
- Boost control is excellent with no overboost events.
- Injection and airflow match well, indicating a balanced tune.
- AFR is in the safe range, with just a touch of black smoke at WOT, which is normal.
Recommendations:
- Keep monitoring EGT, especially for prolonged WOT or towing.
- Consider logging actual lambda for future verification.
- If pre-cat EGT consistently exceeds 700°C, consider backing off WOT duration or upgrading the intercooler.
