Noob here with a basic question. In the fuel maps how close is the cell AFRs to the actual AFRs. Do the numbers in the higher load cells become less accurate to the actual AFR?

 

Up to 100% they are pretty much spot on. Within a few tenths anyway, but after that its modified by a few things and you end up going on prior experience as to what numbers will result in what. Throwing bigger injectors in and getting them accurate seems to get them closer (the AFR numbers) to what they actually are but even then they end up as approximations.

JB

 

As JB wrote.

but to be perfectly clear, the numbers after 100 load are silly, and unless you have changed injectors to a very rare instance those afr numbers are still silly.

Forget those numbers, change them to suit your afr you are wanting, by adjusting them relative to your wideband readings. NOT by changing them to the afr you want.

 

I find that fact rather gaytastic. Life would be so much simpler if that box simply meant what it said.

You'd probably see maybe 2 people offering flashes then.

With proper scaling of the injectors and MAF for any changes made, and disabling lean spool, is it not possible to keep them pretty close to real?

I'm still learning about this too, so don't quote me.

 

^ Sure. But.... lean spool kicks ****!

I dont like messing with the MAF readings. I like to see the freq I'm getting and calculate AIRFLOW from those readings.

Keep in mind once you switch to a open air filter something as simply as removing your splash guard will throw the MAF readings off. I'm still on the stock box and plan on keeping it that way.

 

http://spreadsheets.google.com/pub?k...jfVdIKgha6qJZA

here is an example of an altered map caused by a particular injector. I was able, with a different scaling to get closer to a one to one map, but while trying to find optimum latencies ended up with this one.

I use water injection so my map would be a bit leaner than most, but nowhere near what is indicated here.

 

This is just pure insanity...

Coming from DSM's I have never had to recalibrate a MAF extensively for anything so trivial. In fact...

that includes changing the entire intake tract. filter/intake/turbo/IC pipes/IC, TB/manifold/head/valves/intake cam

I didn't even leave the valve guides in there.
No problems.

Seems like if you sneeze around this one the difference in ambient air pressure will throw it off. What a pita...


What's so different?

 

Think of the value in the AFR map cell just as a number between 8.0 to 20.0 that is used to respectfully rich or lean the fuel by IDC. The only time it becomes calibrated to being close is in stoich where NB O2 sensors start to work (closed loop) the other values in open loop is just a number to feed the fuel

 

Its in a sense a numerical slider...

 

My mapped AFR values are about 1 full point off (rich). so, 10.8 means 11.8 actual. With lean spool off it does get closer.

 

AFR's are approximatley 1 point leaner than your map. If you have a boost leak your car will run significantly richer than your map states. Nothing is silly, nothing is stupid, nothing needs recalibrated.

 

Dan, do you know Kurt from PA?
He's been telling me to get ahold of you about tuning on the Evo.

 

To add to Dan's comment, it will vary based on mods and tuning approach from 1-1.4. Adding things like fuel pumps or injectors or certain intakes will definitely cause substantial change to this.

 

Could it be that the DSMs(and conquests for that matter) WERE actually altered by every change to the system, only the computers were not developed enough to depend as strongly on the readings? I know that the data I got from mine was useless compared to what I now get, and the tuning was crude compared to an Evo. Being a vortex generating device that requires correct harmonics, I would think all Mitsu MAFs are to some extent affected by changes, just some less than others.










of course, this all could be useless ramblings as well

 

So peak torque occurs somewhere between 12 and 12.2:1 so to be conservative maybe use 10.5-10.8? with stock injectors and such.