Bosch MED9.1 on the EA113 2.0 TFSI

Bosch MED9.1 (MED = Motronic Elektronisch Direkteinspritzung: electronic throttle + gasoline direct injection) — VAG 2.0 TFSI EA113, turbocharged GDI petrol. Shares Bosch calibration architecture and label nomenclature with ME7, but runs MPC5xx PowerPC hardware (big-endian) and GDI rail-pressure fueling instead of ME7's C167/port-injection model.

Reference - updated 7 October 2026

The ECU hardware

MCU: Freescale/Motorola MPC5xx PowerPC family (MPC561/MPC563 typical) — 32-bit PowerPC core, BIG-ENDIAN. This is the single most load-bearing fact: unlike ME7 (Siemens C167, little-endian) and MED17 (Infineon TriCore, little-endian), MED9.1 stores 16-bit calibration words MSB-first. Program+calibration live in EXTERNAL parallel NOR flash, ~2 MB (0x200000), 16-bit bus (AMD/Spansion Am29F160-class); note MPC561 has no internal flash (all external), MPC563 has ~512 KB internal, but the practical OBD/bench full image for tuning is the ~2 MB external map. Immobiliser/adaptation data lives in a SEPARATE SPI serial EEPROM (ST 95040 / 95160 / 95320 depending on build) holding SKC/CS/VIN/component-protection — NOT in the flash. PCB carries an MPC5xx BDM (Background Debug Mode) pad set for bench read/write/recovery. Do NOT confuse with TriCore TC1796 (that is MED17, a later generation); MED9.1 is PowerPC.

Fuelling and load sensing

Petrol / gasoline, stratified-capable but runs homogeneous under boost. High-pressure direct injection (GDI): tri-lobe-cam-driven single-plunger HPFP on the head (driven by a bucket cam-follower off the intake cam) feeding a common rail to ~110-130 bar; in-tank low-pressure lift pump ~4-6 bar feeds the HPFP low side. Bosch HDEV5 solenoid injectors. Fueling is rail-pressure setpoint + injector pulsewidth (MED-specific rail-pressure maps), NOT the ME7 port-injection LAMFA/duty model, though the full-load enrichment lambda-target map (LAMFA-class) still exists and governs commanded lambda. Recommended fuel for any tune: 98/99 RON (Super Plus / V-Power / Tesco99); pump-gas timing is knock-limited.

How this ECU is read and flashed

READ/WRITE over OBD: EA113 MED9.1 (Golf Mk5/6, A3/S3 8P, TT 8J) is CAN-based diagnostics (some early 2004-05 cars K-line) using KWP2000/UDS with Bosch security-access (seed/key). It is fully OBD-readable (complete ~2 MB full flash) and writable with automatic checksum correction — it lacks the OBD read-lock / crypto signing of MED17, making it one of the 'easy' VAG ECUs. Tools: MPPS, Kess/KTAG (Alientech), PCMflash (ME9/MED9 module), CMD, Byteshooter, MMFlasher, FoxFlash/KT200. BENCH / BOOT: full read/write and recovery via the MPC5xx BDM pads on the PCB — used for dead-ECU recovery, cloning, and immo work. IMMO/SECURITY (IMPORTANT DISTINCTION): a normal calibration/tune flash on the car's OWN already-matched ECU needs only the seed/key security access — it does NOT require immo-off. Immo-off / immo-matching is a SEPARATE operation, needed only for ECU swaps, clones, virgin/bench ECUs, or removing component protection: the SKC/CS/VIN/component-protection live in the separate SPI EEPROM (ST 95040/95160/95320), so cloning a replacement ECU means copying BOTH the flash AND the matched EEPROM (or performing immo-off = edit the immo routine in flash + patch the EEPROM with its own checksum re-corrected). Do not present immo-off as a prerequisite for tuning an in-car matched ECU.

Engine codes in this family

• BWA (200 PS, K03, transverse — Golf GTI Mk5, A3 8P, Leon)
• BPY (200 PS, K03, US-market — GTI/A3/Passat/EOS)
• AXX (200 PS, K03, early transverse)
• BUL / BWE / BGB (200 PS, longitudinal A4/A6 B7/C6 family)
• BYD (230 PS, factory K04 — Golf GTI Edition 30 / Pirelli, Leon Cupra)
• CDLA / CDLB / CDLC / CDLF (265 PS, factory K04 — S3 8P and equivalents)
• BHZ (early S3 8P 265 PS, K04)

Staging - what each stage really gives

• stage1 - Software only, stock K03 hardware, 98/99 RON. Prerequisites BEFORE mapping: replace the HPFP cam follower with the latest revision (commonly cited 06D109309C or later superseding part) and upgrade the failure-prone diverter valve (rev-G / RS4 / Forge). Typical ~245-265 PS / ~350-370 Nm (from 200 PS / 280 Nm); figures vary by tuner/dyno/fuel. Changes: raise LDRXN + KFMIRL (K03 peak ~1.0-1.1 bar, TAPER at high rpm), add knock-safe timing (KFZW) with IAT/charge-temp correction retained, set WOT enrichment (~lambda 0.80-0.85), raise rail-pressure setpoint, and lift torque limiters / DSG clutch cap in lockstep so the level-2 torque monitor doesn't intervene. Rescale MAF only if it clips.
• stage2 - Stage 1 rescaled for bolt-ons: front-mount intercooler, high-flow intake, turbo-back / downpipe with sports-cat or decat, uprated diverter valve; keep OEM fuel system/injectors and HPFP. Typical ~265-285 PS / ~380-400 Nm. Software: slightly more boost/hold, freer-flow load model, MAF recal if needed, revised timing/enrichment for the cooler/less-restrictive setup. Still K03-limited — the compressor runs out of efficiency and overspeeds past ~1.1 bar.
• stage3 - Hardware turbo upgrade: K04-064, K03-hybrid / TTE (BorgWarner K04-064 internals) up to a big single (TTE480, GTX/GT35). Supporting: S3/RS4 (Bosch) or GM LNF injectors, HPFP internals/uprate (Autotech/Loba-class) to feed the rail, uprated intercooler + charge pipes, uprated clutch (manual) or DSG within/around its clutch limit; forged rods recommended beyond ~350-380 PS and ARP main/crank bolts near ~400 PS. Typical: K04 ~300-350 PS / ~400-450 Nm; hybrids/big singles 400-500+ PS with a full build. Software: injector rescale + dead-time, higher rail-pressure target, boost ~1.2-1.5 bar, timing/enrichment for the new turbo, and torque-monitor + clutch caps raised to match.

Safety limits

• Knock: no sustained knock / ignition-retard (KR) accumulation — per-cylinder knock control must retain full authority; back timing out of any region logging repeated KR. Pump-gas timing is knock-limited, not free.
• WOT lambda ~0.80-0.85 (AFR ~11.8-12.5:1) on 98/99 RON for EGT + knock margin; NEVER lean at WOT (lambda >0.90 under boost risks detonation / melted pistons). Enrich further as load/EGT climb.
• EGT (pre-turbine) ceiling ~930-950 C — the MED9 EGT model (ABGT) enriches and pulls timing to protect turbine/exhaust valves;
• LSPI / low-speed pre-ignition (GDI-turbo 'megaknock'): do NOT demand high load at very low rpm (lugging, ~<2000 rpm); ramp requested load in with rpm in KFMIRL. Low-rpm high-boost pre-ignition is a rod-killer on EA113. Use quality oil / avoid overfilling.
• Boost: K03 peak ~1.0-1.1 bar and TAPER at high rpm (K03 overspeed/surge kills the turbo); K04 ~1.2-1.4 bar; big singles per compressor map. Respect the turbo, not just the target number.
• Transient boost overshoot: keep the boost PID from spiking past the LDRXN cap on tip-in/spool — transient over-boost is the classic EA113 con-rod bender. Tune duty pre-control before leaning on the PID.
• IAT / charge-temp protection: retain the intake-air / charge-temperature ignition-correction (timing pull as IAT climbs), especially on Stage 1 with the stock intercooler and on heat-soaked/track pulls; do not zero it out.
• HPFP / rail pressure: keep the target within cam-driven HPFP capability (~110-130 bar); if rail pressure droops at high rpm the mixture goes lean — cap load or enrich rather than chase pressure the pump can't hold. Keep injector duty below ~85-90%.
• Maintenance hard-stops: replace the HPFP cam follower (latest revision, 06D109309C or later) BEFORE tuning and INSPECT it periodically after — a worn follower gouges the cam lobe and drops rail pressure (lean). Upgrade the failure-prone diverter valve. GDI intake-valve carbon buildup accrues (no port-injection wash) — walnut-blast as needed.
• Mechanical: stock rods good to ~350-380 PS then forged; crank/main bolts near their limit ~400 PS (fit ARP). Con-rod failure is the classic EA113 over-boost outcome.
• Torque-monitor lockstep: modeled torque must stay within the level-2 monitor ceilings or the ECU cuts torque/limp — raise KFMIRL/LDRXN, KFMIOP and the torque limiters together.
• Drivetrain: DSG DQ250 (6-speed wet) clutch torque limit ~350 Nm — keep the torque reported to the TCU within it (or fit an uprated clutch + DSG tune raising the cap while staying within mechanical limits); manual 02Q clutch similar (~350-400 Nm stock). Clutch slip is the usual first Stage-2/3 casualty.
• MAF/airmass: don't drive the hot-film sensor past its measurable range without rescaling, or the load/fuel model goes open-loop-wrong.
• NOTE: no DPF/particulate limit applies — EA113 2.0 TFSI is a gasoline engine without a factory GPF/DPF; do not add a diesel-style regeneration/soot constraint.

Every car using this platform (15)

Stock power and typical remap figures per car. Stage results assume a healthy engine on good fuel.

How confident is this?

Well established: MED9.1 uses a Freescale/Motorola MPC5xx PowerPC processor and is BIG-ENDIAN (PCMflash lists ME9/MED9 as MPC556/562/564, and ECU cloning vendors list MPC561/MPC563). This is the key fact, and it is NOT TriCore. Also well established: ~2 MB of external NOR flash (Am29F160-class); full OBD read/write, with non-cryptographic multi-region checksums corrected automatically by WinOLS/Swiftec/ECM Titanium/PCMflash; a separate SPI EEPROM (95040/95160/95320) for the immobiliser; Bosch map names (KFMIRL/LDRXN/KFMIOP/KFZW/LAMFA) shared with ME7; the high-pressure fuel pump (HPFP) cam-follower requirement; direct-injection rail-pressure fueling; the DSG DQ250's ~350 Nm rating; and the stage power bands. Also worth knowing: a normal in-car tune flash needs only seed/key security access, NOT immo-off (immo-off is only for swaps, clones or bench work). me7sum/me7check are ME7-only and do not correct MED9. Boost-control map names beyond LDRXN/KFLDRL depend on the software version, so don't assume KFVPxx-type names. The BYD engine is a 230 PS K04 (Edition 30 / Pirelli), not a 170-200 PS variant.