After some time reading around I have come up with some good info about mileage, AFR and EGT !
Problems:
1. High EGT @ cruise.
2. **Bad** mileage.
Solutions:
1. 40deg~ @ cruise + 15.5:1 AFR (you can go as lean as possible if EGT is good, there is no knock and no misfire)
2. Lean the map out ! (and read about TPS based AFR table)
The first thing you must understand in the simple truth that if you use less fuel you will have better mileage, simple ah ? turbo likes fuel... we don't like bad mileage, must find good balance...
First thing to do is to tune cruise right, as I stated above, around 40deg~ with lean AFR, you can test how lean you can go just keep in mind, not to high EGT (less then 800C/1500F), no knock and no misfire.
Now cruise is economic as possible.
Tune your idle @ 14.7.
WOT will be 11.5-12.
And the problematic area is the transit area, above 100kpa and below max boost (190kpa in my case).
I use a small turbo (TD04-13C, 40/53mm compressor), every little tip on the gas pedal will get me in to boost (above 100kpa), it can happen starting from a stop light or passing lanes or cars on the highway - when there is no intention to get into boost.
On a "normal" rich AFR map you will see AFR drop from stoich when approaching 100kpa and when passing it it will drop even more - it does not matter how long you "visited" those areas.
We can try and set the AFR table for lean AFR @ 100kpa and above - all before max boost, but it will result a very lean mixture @ 100kpa, if we ever run N/A again it can be a problem. (some times I disconnect my WG in order to run N/A)
Well, a friend of mine told me he runs a TPS based AFR table... very interesting...
AFR will change according to your TPS, high TPS = low AFR, low TPS = high AFR.
It leads to 14.7 in boost sometimes O_O - but for a brief moment while I check my EGT and knock.
He runs this map a few years with great results, I'm starting now - hoping to get good mileage too.
AFR based on TPS as load:
How to enable TPS as load for AFR:
