Three KBs from our May 2026 Q&A live form a tight mini-cluster on boost-control across modern Bosch ECUs — diesel EDC17 (where pressure maps have bugs or were removed entirely) and gasoline MED17 (where the limit hides in Protection, not where you’d look).
If you’re hitting unexpected boost behaviour after a tune — these are the three places to check first.
KB-12 — Where do you find the pre-injection map on EDC17 CP44?
The trap: CP44 stores pre-injection as 8-bit values on 16-bit axes — WinOLS shows them as 14×20 looking maps, not the 16×16 you’d expect. Easy to miss in a map search if you filter on 16-bit only.
KB-13 — Where is the boost pressure limit on a VW MED17 (and how to set 0.5 bar)?
The trap: Modern Bosch moved away from pressure limits to flow limits. But the pressure cap didn’t disappear — it stayed in the Protection / error tables section, looking like a diesel-style limit (atmospheric on one end, unrealistically high on the other). Most tuners scroll past it looking in the boost-control area.
KB-14 — Why do EDC17 boost maps look broken — and why did Bosch switch to mg/cycle?
Two traps in one:
- BMW EDC17 (C41 in this case) ships factory bugs — WGDC and boost-request maps with broken zones because the Bosch map-generation algorithm sometimes produces garbage values. Flatten the broken zones; the pair map carries the real shape.
- Bosch switched from pressure-request (mbar) to combustion-chamber-charge (mg/cycle) when EDC17 went from C46 to C64/C74 — then partially walked it back. If you’re stuck reading mg/cycle and want to think in mbar, WinOLS Properties → Conversion (factor + offset) recovers the pressure view.
How these three fit together
Reading the cluster top-to-bottom gives you the modern Bosch boost-control mental model:
- KB-12 = how to find injection maps when the encoding hides them (CP44 8-bit quirk)
- KB-13 = where the protection limit lives when it’s not where you’d expect (MED17 Protection section)
- KB-14 = how to read boost when Bosch reformatted the request entirely (mg/cycle ↔ mbar conversion + factory-bug awareness)
Together: 8-bit encoding pitfalls, protection-section hide-outs, flow-vs-pressure substitution. Three angles on the same broader truth — Bosch keeps changing where and how these maps are stored across firmware generations. If your habit is “I always look in folder X” — that habit breaks across CP44 → C46 → C64/C74. Read the encoding before you read the values.
Want to see these maps walked through live?
These KBs come from our monthly Open Q&A live with Thomas. Members bring their own files, Thomas opens them in WinOLS on screen, walks through the maps in real time.
Register for the next Open Q&A → — agenda forming, free to attend, recordings available to Members.
Related on Tuners Guild
- Bosch EDC17 pillar (Tuners Guild blog): Bosch EDC17 tuning guide → maps through physics (Maps referenced table now includes all 3 of the above KBs)
- MED17 torque conversion path: KB-11 — full MED17 torque chain (pairs with KB-13 for the protection layer on top of torque request)
- Diesel injection — Pre/Post 4-tell method: KB-01 (pairs with KB-12 for the encoding-vs-identification angle)