Bosch ME7.1 on the transverse 1.8T

Bosch ME7.x transverse petrol — 1.8T 20V single K03/K03s (VW Golf IV/Bora/New Beetle, Audi A3 8L/TT 8N, Seat Leon/Toledo, Skoda Octavia). PART-NUMBER ACCURACY: these transverse 1.8T codes are almost all Bosch ME7.5 / ME7.5.1 / ME7.5.2 (Bosch part-number family 06A 906 032 xx / 06A 997 032), NOT literally ME7.1.

Reference - updated 4 August 2026

The ECU hardware

Siemens/Infineon C167-family 16-bit main CPU (SAK-C167CR/CS-derivative, ~24-40 MHz depending on box; on-chip RAM + monitoring module). External parallel program/calibration flash: AMD/Fujitsu/ST 29F-series (Am29F400B = 4 Mbit/512 KB, or Am29F800B = 8 Mbit/1 MB device) in 44-pin PSOP/TSOP. The transverse 1.8T ME7.5 image is 512 KB (0x00000-0x7FFFF); the 1 MB / 0x100000 image is the 2.7T-class ME7.1.1 longitudinal sibling. Immobilizer/adaptation/odometer live in a SEPARATE serial EEPROM (93C56/95040-class SPI/MicroWire chip), which is NOT part of the flash bin and is read/written separately.

Fuelling and load sensing

Petrol/gasoline, port fuel injection (MPI, 4 injectors), turbocharged (single K03 or K03s). PRIMARY load sensing is the hot-film MAF (HFM5) mass-airflow sensor (voltage→airmass via the MLHFM transfer curve), converted internally into relative cylinder charge (rl); a boost/manifold pressure (MAP) sensor is used for BOOST CONTROL, not as the primary load signal — this is a MAF-based torque-structured system, NOT speed-density. Lambda-1 closed loop at part load, open-loop enrichment at full load. NOTE: this is LOW-PRESSURE port injection (~3-4 bar returnless/mechanical) — there is NO high-pressure pump or fuel rail to tune (contrast later FSI/TFSI direct injection), so the fuel-delivery limit is injector flow/duty, not rail pressure.

How this ECU is read and flashed

PRIMARY (in-car): full read/write of the 512 KB flash over OBD-II K-line using KWP2000 (ISO 14230) with a cheap FTDI-based KKL/dumb-K cable + a free open-source OBD flasher. It uploads a RAM bootstrap loader then flashes at raised baud; full read ~4-6 min, full write ~3-4 min; supports full-flash and calibration-only writes with verify. Use a genuine FTDI cable — CH340/counterfeit cables are unreliable for flashing. SECURITY: KWP2000 SecurityAccess 0x27 seed/key — the standard ME7 seed/key is public; no external unlock needed for these box codes. IMMOBILIZER: on 1.8T ME7.5/ME7.1 the immo lives in the SEPARATE serial EEPROM + instrument cluster and does NOT gate program/calibration flashing — you can read/write flash immo-on over OBD (the easy, well-trodden case; contrast the newer 4Z/2.7T longitudinal boxes where full flash is immo-gated behind 10 85). BENCH/BOOT (only for a bricked or fully-locked ECU): C167 bootstrap loader (BSL) over K-line with the internal boot-strap pin pulled, or BDM/bench programmer reading the 29F device directly (immo-immune). EEPROM (immo/SKC/odo) is read separately via KWP1281 in-car or on-bench.

Engine codes in this family

• AGU (150 hp, early K03, Golf IV/A3 8L)
• AQA (150 hp)
• ARZ (150 hp, Leon/Octavia/A3)
• AUM (150 hp, K03s)
• AUQ (180 hp, K03s, Leon Cupra/A3/TT)
• AWU (150 hp)
• AWD/AWW (150 hp, US MK4 Jetta/Golf/Beetle)
• AWP (180 hp GTI/GLI, K03s)
• AWV (150 hp)
• BKF (150 hp)
• BVP/BBU/BJX (150 hp EU) — same ME7.5 family. VERIFY the code off the block AND the ECU box code before choosing a base bin; this list is indicative, not exhaustive, and several 1.8T codes share/overlap datasets.

Staging - what each stage really gives

• stage1 - Software only, stock K03/K03s and stock hardware. Raise LDRXN/KFLDHBN + KFMIRL for more boost (peak ~1.0-1.1 bar on K03s vs ~0.7-0.8 stock, tapering toward redline), optimize KFZW/KFZW2 timing, set LAMFA ~0.83-0.85, retune N75 duty (KFLDRL) + PID, and scale KFMIOP + the level-2 torque ceilings to match. Typical: AGU/150 hp K03 -> ~180-190 hp / ~215-225 lb-ft; K03s 150/180 hp -> ~200-215 hp / ~240-260 lb-ft. Requires good fuel (95+ RON EU / 91-93 AKI US).
• stage2 - Stage 1 + bolt-ons: catless/high-flow downpipe + exhaust, larger front-mount intercooler (FMIC), intake, uprated diverter valve, often a 3" MAF housing. If the MAF bore changes you MUST rescale MLHFM. Hold more sustained boost near the K03s efficiency/heat limit. Typical: ~220-235 hp / ~260-290 lb-ft. Stock clutch begins to slip here and stock injectors approach their limit; the stock MAF starts to saturate near the top of this range.
• stage3 - Hardware: bigger turbo (K04-0xx hybrid, or larger frame e.g. GT28xx/Garrett) + matching injectors (380-440cc+) + uprated fuel pump + FMIC + upgraded clutch + a LARGER MAF housing (stock HFM5 saturates). Full recal: KRKTE + TVUB for the injectors, MLHFM rescale for the new MAF, new boost targets/PID for the turbo, and fuel+timing for the new airflow. Typical: K04 ~240-280 hp; larger frame ~300-400+ hp with supporting mods. Mandatory clutch; forged rods/pistons recommended beyond ~320-350 hp.

Safety limits

• Knock/timing: zero SUSTAINED knock. ME7 knock control retards per-cylinder (KR); a safe tune keeps average retard minimal (transient only, target < ~3-4 deg pulled) — constant KR means KFZW/KFZW2 is too aggressive for the fuel/boost.
• WOT lambda/AFR: target ~0.80-0.85 (AFR ~11.8-12.5:1) under full boost; NEVER lean past ~0.90 (AFR >13.2) at high load/boost. The ECU applies the RICHEST of LAMFA/LAMFAWKR/KFLBTS (final lambda = MIN) — edit all three so none silently overrides you.
• EGT: keep < ~900-950 C pre-turbine on the cast K03/K03s manifold+turbine; Manage via LAMFA/KFLBTS enrichment + timing; if you scale the MAF, re-check the KFLBTS EGT trigger (TABGBTS).
• Boost: K03 safe peak ~0.9-1.0 bar, K03s ~1.0-1.2 bar peak tapering to ~0.7-0.8 by redline. Avoid compressor surge and heat-soak past the turbo's efficiency island; keep the LDRXN/KFLDHBN ceiling above your target and the overboost-deviation cut un-disabled.
• IAT / heat-soak: the small K03/K03s (top-mount charge path, weak or no FMIC) heat-soaks fast -> knock. Keep KFTARX (load pull vs IAT) and KFZWWLNM (timing pull vs IAT) INTACT;
• MAF saturation: the stock HFM5 transfer (MLHFM) clips at high airflow (around Stage 2+); a saturated MAF makes the ECU UNDER-read load and go LEAN at exactly the worst time. Fit a larger MAF housing and rescale MLHFM before pushing airflow past the sensor's ceiling.
• Torque monitor (level 2): keep basic/requested torque within the miszul-class ceilings (scale KFMIOP + the monitor with KFMIRL) or the ECU applies torque intervention / limp / EPC.
• Fuel system (PORT injection — no HPFP/rail limit): stock injectors (~210-280 cc by code) top out ~ mid-200s hp; stay < ~85-90% injector duty. Beyond that fit bigger injectors + uprated pump and rescale KRKTE + TVUB.
• Rev limiter: stock ~6800-7000; raising past ~7200 stresses valvetrain/rods for little gain.
• Engine internals: stock cast rods/pistons reliable to roughly ~300-320 hp / ~350 lb-ft; forged internals beyond.
• Clutch (manual): stock clutch slips around ~250-280 lb-ft — upgrade for Stage 2+.
• Automatic (01M 4-speed tiptronic): the ECU requests torque reduction to protect the box; the 01M is torque-limited and overheats/slips under big torque — respect the transmission torque limit (or upgrade) on auto cars; do not simply raise all torque ceilings on a tiptronic.
• Catalyst: on cars retaining the cat, sustained over-enrichment or misfire overheats/destroys it. (No DPF on these petrol turbos, not applicable.)
• Integrity: ALWAYS re-correct main + multipoint checksums (ME7Sum) and VERIFY (me7check) after edits, and keep a verified stock backup before any write — a bad OBD flash can require boot-mode/bench recovery.

How confident is this?

HIGH on: hardware (C167 core + 29F-class parallel flash, 512 KB transverse image), OBD K-line/KWP2000 flashing with the known 0x27 seed/key, the no-crypto additive MAIN + MULTIPOINT checksum scheme and ME7Sum/me7check correction, the core tunable map set and roles/lockstep (KFMIRL/KFMIOP, LDRXN/KFLDHBN, KFZW/KFZW2, LAMFA/LAMFAWKR/KFLBTS with richest-wins MIN, KRKTE/TVUB, MLHFM/KFKHFM), and the staging power bands — corroborated by s4wiki, ME7Sum and the 1.8T communities. CORRECTIONS applied vs the draft: KFLDIMX is the boost-PID integral-regulator CLAMP, NOT the overboost fuel-cut (the cut is the plsol-plist deviation / LDRLMX-class); the MAF map to rescale for a housing change is MLHFM, not KFKHFM; injector dead-time is TVUB, not 'KFKTE'; KFLDHBN is a real pressure-ratio ceiling (belongs with LDRXN); torque-limit labels are miszul/KFMIOP-class, and 'MDMAX/MDFAW' are not the ME7.5 1.8T names; removed the unverified 'CheckMate' corrector (real ones: ME7Sum, me7check, MTX Electronics TunerPro plugin, ECUFix, WinOLS). MEDIUM on: per-map endianness (word tables are usually MSB-first but MUST be validated per map), the exact overboost-cut and level-2 torque-limit va