S4wiki:Community Portal

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To do lists

Questions that need answering MAF 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? Lemmiwinks High EGT (>980°C) and IAT (>120°F) corrections.. is there a flag for each, or is the correction progressive? does it affect both fueling and timing? does it affect req boost? does it affect load calculations? The load discussion in the lemmi article is pretty much 100% bullshit. hopefully somebody can fix it Generations There is some confusion with cars near the 09/00 build mark Some are 2001, some are 2001.5 (no verification of this rumor) Some 2001.5 came with h-boxes and do not appear to have F-hoses (doubtful, probably incorrect report) 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 Glossary 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? ME7.1 sigh. stub for now.

Articles that need content Load (aka Charge?) vs Torque self study refers to the following "torques" external torque requests internal torque requests nominal inner torque (spec torque?) self study refers to the following "charges" actual charge (calc load?) nominal charging moment (spec load?) nominal charge (spec load corrected?) Open loop/closed loop What determines which is used when? 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) 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. Knock control Relationship between KVs and timing correction factor Direct? Filtered/corrected somehow? Are logged KV's corrected? Characteristic curve When is it consulted? During both open/closed loop? Is MAP used? What if ECU detects broken/unplugged MAP? Manifold air pressure Synchronous path/Asynchronous path Synchronous path outputs: VVT, ignition timing, injector pulse width Asychronous path outputs: requested boost, throttle plate angle Variable valve timing F-hose Why does it exist? Delete howto Master boost controller Parallel vs series vs alone Tuning Relation to throttle cut and TCD Throttle cut defender aka MAP clamp N75,N249,Wastegate N75 controls wastegate N249 controls BPV