S4wiki:Community Portal

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The Community Portal is the central place to find out what's happening on S4Wiki. Learn what articles need to be written, what questions need to be answered, and what articles still need a lot of work.

If you wish to edit this page, please see Wikipedia's Community Portal for an example of how a wiki community portal should look.

If you are looking for other external Audi S4 related sites, check out the external links page!

To do lists

Questions that need answering


  • Bosch signal characterization
  • What voltage indicates "zero" flow?
  • What voltage indicates negative flow? Does the ECU use it?
  • Is MAP used in characteristic curve when ECU detects broken/unplugged MAF?
  • Near the top of the MAF range, it seems to have a smaller and smaller effect on fueling. Does this mean that maxing the MAF isn't as bad as many believe?


  • The load discussion in the lemmiwinks article is a now bit better, but still missing where the open/closed loop decision is made.


  • There is some confusion with cars near the 09/00 build mark
    1. Some are 2001, some are 2001.5 (no verification of this rumor)
    2. Some 2001.5 came with h-boxes and do not appear to have F-hoses (doubtful, probably incorrect report)
    3. Still trying to figure out what the AGB engine code is
  • 05/01 and 06/01 cut-off date for 2001.5 and 2002 MY may not be 100% accurate
    1. The 2001.5 Tiptronic is listed with build date of 05/01 with L or M box ECU.
    2. The 2002 Tiptronic is listed as build date 06/01 with AA box ECU.
    3. However, my 2002 Tiptronic has a build date of 05/01 and came with an AA box ECU.

Articles that need work

Long term fuel trim/Short term fuel trim

  • These articles were directly stolen from this BMW OBD-II article. They need to be checked for accuracy wrt. the S4 and ME7.1


  • huge disaster in general. currently just redirects to list of abbreviations. Should get rid of redirect and make a good one.

Bypass valve

  • need more part number information
  • need to reformat into a table
  • need more revision information (and pressure specs etc)

Cluster recode

  • verify there is only h-box/m-box encoding
  • is there tip/6sp variation?

Engine recode

  • different between ESP/non-ESP, but how does it interact with ABS and EDL?

Articles that need content

ECU Explorer

  • USB driver howto
  • registration key guide

Load (aka Charge?) vs Torque

  • self study refers to the following "torques"
  1. external torque requests
  2. internal torque requests
  3. nominal inner torque (spec torque?)
  • self study refers to the following "charges"
  1. actual charge (calc load?)
  2. nominal charging moment (spec load?)
  3. nominal charge (spec load corrected?)

Open loop/closed loop

  • What inputs are used in each to determine fueling
    • closed loop: req load-> base maps + adapt channels + ltfts (derived from stfts) + stfts?
      • stfts derived from narrow band
    • open loop: calc load (from maf) + req load -> base maps + EGT enrich + adapt channels
  • What inputs are used in each to determine boost
  • What inputs are used in each to determine timing
    • calc load (from maf) + req load -> base maps + IAT correction + retard (derived from correction factor)
      • correction factor derived from kvs
  • What inputs are used in each to determine throttle plate angle
    • req load (based on throttle position during partial throttle or target idle torque if throttle postion is zero) vs calculated load (based on MAF)
    • add in cruise control, traction control, engine protection (e.g. throttle cut)

EGT enrich

  • two thresholds
    1. 980C, direct from EGT sensor, which does not read below 945C (1733F)
    2. 500C, from calculated EGT, which is derived from load/RPM

O2 sensor

  • Narrow band sensor - only accurate near stoichiometric A/F. Only good for closed loop.
  • Wideband sensor - accurate everywhere! Great for tuning open loop.

Timing and Knock control

  • Relationship between KVs and timing correction factor
    • Direct?
    • Filtered/corrected somehow?
    • Are logged KV's corrected?
  • Relationship between IATs and timing maps

Characteristic curve

  • When is it consulted?
    • During both open/closed loop?
  • Is MAP used?
  • What if ECU detects broken/unplugged MAP?

Synchronous path/Asynchronous path

  • Synchronous path outputs: VVT, ignition timing, injector pulse width
  • Asychronous path outputs: requested boost, throttle plate angle

Variable valve timing


  • Why does it exist?
  • Delete howto

Manual boost controller

  • Parallel vs series vs alone
  • Tuning
  • Relation to throttle cut and TCD

Throttle cut defender

N75, N249, Wastegate

  • N75 controls wastegate
    • how is req. boost related to waste gate duty?
    • why delete? (to use MBC, AVCR etc)
  • N249 controls BPV
    • why delete? (no conclusive proof of any advantages)

RNS-E Nav information