Hey guys,

I'm making good progress from when I bought this car.

Before my mileage was 15/21, now it's 21/27.7. not bad for 400whp

I'm using open loop cruising and here are my AFR and Timing tables:




I do have something I want to refine further but cannot locate the table that would affect it....

Example - While cruising and holding throttle steady i usually get close to my target AFR (15.3-15.7) however, sometimes on downgrades or VERY slight throttle lifts where I'm either still maintaining speed or VERY slightly decelerating, I see the AFR richen to 13.x and I'm not sure why.

Any way to keep it at target AFR even during very slight throttle lifts, or small downgrades?

In case you're wondering, it does cut fuel on full throttle lift just fine.

 

First off, nice job on the fuel economy. Always bugs me when someone brings up economy and someone reacts more or less like "HEY! It's an EVO!!! It's not ALLOWED to have decent fuel economy!".

Is your EGR advance enabled? What octane fuel are you running?

As for the issue you're talking about, I think I have something similar. It typically happens in 5th gear around 2k rpm, maintaining speed. If I ever so slightly lift off or start going up a hill, AFR dips into the 10's until I just lift completely to get it to "reset". I've wanted to try SD for a while to see if it would fix this.

 

Are you able to adjust the fuel map at those extremely low load zones to achieve target AFR? It seems to be something I noticed with my standalone too, although I am not sure whether or not if I have tuned it 100% for those conditions. I wonder if theres a level of inaccuracy or tolerance that we must consider, or overall fuel calculations are different at such low airflow.

What does your mivec map look like during cruise? Are you using EGR ignition advance and/or EGR system also?

EDIT I was apparently typing my message the same time as RAPTORD. ( yes I had internet tourettes )


There are a few threads around that especially detail things used to increase MPG. mrfred did one analyzing MIVEC advance I believe. I think 5% was the max gain he noticed from MIVEC tuning at cruise. However Id search for the thread.

 

Thanks! I agree, why not tune mileage as well... Just something else to tune for

I do have EGR enabled and the egr tables do have entries to add timing... but for some reason the car is not adding any during cruise. Idk... so I set timing to 41 and called it a day

I also wonder if SD would fix it... But we shouldn't have to go to SD to remove it!

 

First, thx for the post. I too have an interest in this. There are a couple of really good threads on the topic. nice gains by the way. I am at 21 combined and 26 hwy at 70-80mph ave. Check this thread out..Timing vs MPG (Closed Loop)
Not an expert but you may want to smooth your fuel table--looks like some broad jumps in fueling from cell to cell.

 

I'll have to log when this happens, but I don't think load drops that much... If so, I doubt I'll rescale my map for lower load

Thanks for the Mivec idea, I'll look at that. I'll post my mivec soon for you guys to look at.

 

Good mileage gains there, its nice to see someone else having a go at the economy side of tuning.

As for the enrichment on lift-off (it only does it when load was above a set value, like about Ev80% or so), I have been chasing this for four years, without success.

I asked mrfred too but we did not find an answer that worked. I believe it is some extra code/map/table thing we have not identified as yet. It is in USDM and AUDM evo9s, and its driving me nuts!

 

Well.... at least it's not me

Guess I'll play around with mivec and see if I can actually get egr advance to work.... Im aiming for 30mpg

 

That's my goal too My best so far is 29.3 mpg.

 

Post up your maps for comparison!

 

I gotta improve over my 21 highest highway.. I'm on a standalone but Id think same princeples

 

niceeee

 

i'll be curious to see your mivec results.

for the 13:1 afr on slight downgrades, are you still applying throttle? i'd like to see what maf hz values if still some throttle.

if you have an adjustable dv, another supposed trick for better mileage is to set the preload/spring soft enough for the valve to be open at cruise. this lets the turbo spin more freely creating less backpressure at turbine inlet and comp outlet. i read about it in a motoiq article a few years ago. i've not tried it yet.

 

Subscribed.

 

You should smooth your maps a little bit and when you...

NMAFR = DAFR * MAFR / AAFR

This is the formula for adjusting the fuel map. This is the fuel map AFR (MAFR) and the actual AFR (AAFR) is the value from your log. (DAFR) is the desired AFR.

I had a 3000gt NA which I ran open loop 15.5 on idle and 16.2 on cruise. I did get exatcly 30mpg.

I want to do the same with my evo but I havent touched it yet.... but i am happy that someone else is doing this!!

I did get knock sometimes like 2 times a month.. on really cold days.. so i think is better to cruise at 16. and EGT gauge could be really useful too. IMO.