Anyone ever do any AFM tuning?

[kronus]

I've heard some people mention that our AFMs (for m20s and m30s) let you adjust AFR.

Some searching has produced these images:




Anyone ever do this? What were your results?

[Sagaris]

I am just about to make some adjustments on mine with a wideband. My AFR's are absolutely spot on right now with the correction the oxygen sensor gives in closed loop (14.6-14.7:1 and stable during part throttle cruising, 14.3-15.0 transient AFR during part throttle acceleration, quickly stabilizes at 14.6-14.7:1, 13.6-14.0:1 during full throttle) I am very suprised at how well the old Motronic 1.3 + AFR combination does.

With the oxygen sensor unplugged and running just off the base map in open loop there is definitely a loss of power on the butt-dyno. I have been too busy to run the wideband in open loop to see how the base map is but I think it is on the rich side. Within the next week I should have the opportunity to mess around with the wide band to see what the AFR's look like in open loop and see how tweaking the AFM changes improves things just running off the base map.

[nando]

you can try, but most likely it's just going to mess up the part throttle calibration of the AFM. and if you have a working O2 sensor, it's not going to help you as the AFM is mostly ignored at WOT and it will use the long term trims to bring it back to whatever it's programed to target from the factory.

[jlevie]

You can affect the A/F ratio below 4500rpm at WOT by changing the clock spring tension in the AFM. But understand that unless you disconnect the O2 sensor and live with a constantl CEL, that the DME will adjust fuel trim in an attempt to get to stoich (14:1) operation. Also understand that above 5000rpm the DME uses built in maps referencing only rpm, engine temperature, intake temperature, and learned adaptation if the O2 sensor is functional.

The only real way to affect mixture is to change the base fuel maps (and engine timing) with a chip, WAR chip, or similar. Even better would be to replace the OE DME with a MegaSquirt. Oh yeah, and DIY tuning will require the services of a dyno so you can see what you are doing.

[ACHTUNG]

Maybe you can get some info from this thread:

http://www.r3vlimited.com/board/showthread.php?t=127943&highlight=M30+AFM