VE tuning means to tune for the right mixture for your engine.

Please see [ve tune by statistics] (live analyzer for VE, lambda)

note: Beware that if misfire happens (eg. HV cabling/connection problem), or other problems (eg. ignition sparkadv angle or base timing is way off, or ignition dwell too low, or too high), the VE tuning will NOT magically solve those.

The rest on this page is about the method... (of various age, most might be useful, some parts already made much simpler by the tool) - most users will use the above tool nowadays - but knowing the method is always good.


The allowed EGO-correction authority range depends on the tuner and the engine though. Tuners who think they can tune perfectly their own way (wether open-loop or closed loop or phase-of-the-moon), just neglect any text on tuning and related technologies (such as wideband and closed-loop tuning) and continue their own way. It's their decision with no effect on others (except when spreading rumours). Fortunately they don't need help anyway.

Important warnings

An introduction to the different ways to tune a 'True VE' engine management system.

A popular and effective way in short: use closed loop WOT during tuning and you basically tune by adjusting the VE table until you get minimum EGO correction.

The counterrecommended way of tuning a system' that is capable of running closed loop at full throttle is to allow it to add and subtract around +-15% fuel depending on the input from the WBo2 sensor. This might work well, there are however a phenomen that make a WBO2 sensor read a missfire as a lean condition. If the ECU is allowed to enrich based on that false lean reading the missfire condition usually get worse regardless of the original reason for the missfire. For someone that is is a bit unexperienced it's very hard to diagnose the problem correctly and for an experienced tuner it's easy to overlook it.

The recommended way to set up closed loop operation to allow around -15..23% enleanment but only +1..4% enrichment: you eliminate 99% of all potential false readings.

Note that the ego authority range ("window") didn't change at all 1.15/0.85=1.04/0.77=1.35 (~ appr 35%)

Why NOT to use closed loop tuning

EGO correction

Let's say one wants to maintain an appr 20% authority for EGO correction. This is a decision of the tuner. This might be reasonable for production operation (street / racing). During tuning, often a bigger authority is used. Lower (than 20%) authority makes sense when the WBO2 sensor is to be removed (for whatever reason?) after tuning. Also, smaller (but non-zero!) authority range is usually used for extremely fast-revving engines.


The image shows a range of VE=162 .. 202 configured in 2 different ways:

One might believe (before thinking about it) that setting ego_rich_limit higher than ego_lean_limit is the way to go. But there are very good reasons to use the "good" method which relies on ego_lean_limit rather than ego_rich_limit. Makes little difference when the authority range is small.


Why is the "good" (recommended) better than the "bad" (counterrecommended) ?

Also, (for the case when WBO2 sensor fails), engines tolerate rich condition much better than lean condition.

This justifies adjusting higher (richer) than required VE values, and only allow a marginal ego_rich_limit, effectively stuff most of the ego-correction authority in the ego_lean_limit.

There were good reasons in the past (eg. WBO2 or proper EGO-correction not available) It's just harder, takes more time and involves more risk.


See also