13B-MSP Engine Running Data
Logged oil pressure, oil temperature and OMP behaviour from a running Series 1 13B-MSP — including a reconstructed stock oil metering map from idle to 9,500 RPM.
This page publishes baseline data I logged from a running Series 1 13B-MSP during my EnduraOMP project. As far as I’m aware, no published dataset existed linking the Renesis OMP’s commanded position to actual oil delivery, so this was measured from scratch. It’s shared here as a reference for anyone tuning, diagnosing, or designing around the stock lubrication system.
How the Data Was Gathered
Oil delivery can’t be measured directly on a running engine — putting a flow meter or restriction into the live OMP circuit risks starving the engine and wiping out the apex seals. The measurement was therefore split into two stages:
-
On-engine logging. Oil pressure (external transducer in the oil filter gallery) and oil temperature (thermocouple alongside it) were logged continuously through an ESP32 data acquisition system, time-synchronised with OBD data streamed over Bluetooth. The ECU’s commanded OMP stepper position (
MOP_POS) isn’t available through standard OBD-II PIDs, but can be read through manufacturer-specific parameters using Forscan. Steady-state holds were captured at 2,000 / 3,000 / 5,000 / 7,000 / 8,000 / 9,000 / 9,500 RPM after warming to ~70 °C oil temperature. -
Bench flow characterisation. The stock OMP was then mounted on a bench rig and driven with an ESP32 and DRV8825 stepper driver at the same commanded positions logged in stage 1. At each position the pump ran for a fixed 30 s interval and the delivered oil volume was measured, giving flow rate in ml/min.
Combining the two stages reconstructs the effective relationship between engine speed, commanded OMP position, and oil delivery — without ever putting the engine at risk.
Operating Envelope
Across the full running test, the engine and lubrication system covered the following envelope:
| Parameter | Range observed |
|---|---|
| Engine speed | ~709 – 9,480 RPM |
| Oil temperature | 18.1 – 108.8 °C |
| Oil pressure | 1.16 – 4.88 bar |
The headline finding: oil pressure is not governed by RPM alone — thermal state has a strong influence. Pressure rises with engine speed but falls as oil temperature rises, which shows up clearly when comparing idle states:
| Condition | RPM (avg) | Oil temp (avg) | Oil pressure (avg) |
|---|---|---|---|
| Cold fast idle | ~1,290 | 36.5 °C | 3.38 bar |
| Hot idle (fully warm) | ~820 | 104.9 °C | 1.22 bar |
Same engine, same idle — nearly a 3× difference in oil pressure purely from thermal state.
At higher speeds, pressure rises but approaches a bounded upper range rather than climbing indefinitely:
| Condition | Mean oil pressure |
|---|---|
| Steady cruise (~3,000 RPM) | ~3.39 bar |
| Medium-load acceleration | ~4.08 bar |
| Upper high-load sweep | ~4.75 bar |
| Observed peak | < 4.9 bar |
Stock OMP Metering Map
The reconstructed stock control schedule shows a progressive — not linear — increase in metering with engine speed:
| Engine speed | Commanded step (approx.) | Derived oil delivery (approx.) |
|---|---|---|
| 1,000 RPM | step 3 | 0.15 ml/min |
| 3,000 RPM | step 9 | 0.62 ml/min |
| 6,000 RPM | step 24 | 2.25 ml/min |
| 9,500 RPM | step 47 | 6.46 ml/min |
Mid-range delivery stays modest, then ramps steeply toward the top of the rev range. For context on what these “steps” physically mean — the stepper motor changing the pump’s effective plunger stroke — see how the OMP works.
Combustion Signals (Benchmark Only)
Lambda, fuel trims and pre-cat oxygen sensor data were logged alongside, primarily as a benchmark for later lubricant comparisons. Behaviour matched expectations: rich operation with high HC/CO at cold start and early fast idle, stabilising close to λ = 1.0 at hot idle and steady cruise, then enriching again under high load.
Caveats
- The bench flow stage measured relative delivery at each commanded position — absolute system back-pressure was not replicated, so treat the ml/min figures as a well-grounded characterisation of the stock schedule’s shape and scale, not a calibration-grade absolute map.
- Data is from one healthy Series 1 engine. Worn pumps, different oils and different sensor placements will shift the numbers.
- Step commands were read via Forscan’s enhanced PIDs (
MOP_POS); standard OBD-II readers will not show this parameter.
This dataset fed directly into the design requirements for EnduraOMP, my MEng project replacing the stock metering system with a closed-loop electronic one.