SeanV

MY Evo is currently running ROM ID 96530706 and the below is all on pump gas.

First off, I have successfully dialed in my fuel trims for PTE 780 injectors.

My low LTFT is sitting at -2,8% or so.
My mid LTFT is sitting at -1% to 0.1%.

On idle and cruise my AFR's sit at 14.6-14.7 as measured by my LC1 with the probe at the end of the downpipe, and when I go WOT, I am measuring .1-.2 leaner AFR's from what is in my fuel map.

So based on the above it looks like my fueling is about as good as it can get with regards to the trims/scaling.

I then force the car into full time open loop using Perh FAA bit4 = 0. (Lean spool is also disabled)
My fuel map has the AFR's in the idle and cruise load cells set to 15.4 for economy driving.
While in idle and cruising, I am measuring low 14's on my wideband.
It ranges from 14.0 to 14.3 with the car in full time open loop.

I can't understand why... I was expecting to see my AFR's in idle and cruise a lot closer to the values is in my fuel map while in idle and cruise.
Especially since my closed loop operation and fuel trims seems to be pretty much spot on.

Anybody have any ideas why there is a big discrepancy in my measured AFR's and fuel map, when in full time open loop?

Thx.

Edit: Fuel map attached

nothere

iTrader: (23)

if I understand you, you expect the fuel map to be indicative of the afr?

this will not happen, don't expect it. the way the map /ecu works its to dependent on injector scaling and latencies.
the 14.7 that you thought were fuel tuning numbers were simply a false front that did nothing (while in closed loop).

you can do a math calc and get the afr you want or just start adding to the numbers you have to get what you want.

as an approximation about three or four bumps equals 1 afr.

hediki12

hey i havent tried this formula yet (no wbo2) but ive seen it alot. so hopefully it will work. also theres an exel file that does the math for you .. so umm give it a shot and let me know if it works . ill upload it and you can get it the older exel version or the newer one

SeanV

Thx, I will give it a try.

Appauldd

iTrader: (22)

Do you have the EGR disabled?

hediki12

yes the egr disable will help as well...

SeanV

Perph FAA bit11 = 1.
therefore EGR is disabled?
And EGR timing advance maps all set to 0.

AIK

SeanV

You need.
1. Turn on open loop.
2. To pick up scaling values so that in the middle of a table (80-140 load) values of a mix in a table were similar to the real.
3. To pick up latency values so that in the table beginning values of a mix in a table were similar to the real.
4.Manually to pick up such values in the end of a table that the real mix was such what you want. Values in a table and a real mix on boost will not be equal.

With such approach you will receive a real mix 15.3 on small loadings in open loop. But your trims my be wrong and you may have 0170 code anytime.

jrohner

You probably just have the latency settings a little off. Take a little out to lean it out at part throttle. If that doesn't quite do it right, you need to adjust your MAF scaling a bit.

SeanV

Thx guys, just about were I want to be with the AFR's now in permanent open loop.

hediki12

kool. so the calculations work good? I'm planning on running full time o-loop as well for fuel economy sake. lol.