Afm Reading.

[mad082]

does the rb25 afm keep reading past the point where rich/retard mode would normally kick in on a stock ecu? or is that where the afm is at max voltage?

i know that you can change afms, but i am just curious as to whether the stock afm keeps reading past where the stock ecu normally cuts out.

[paulr33]

rich and retard isn't at 5 volts if that helps.

i think its a ramp based scale where it decides to turn on rich and retard, i dont think its a flat 4.01v or higher trigger

[mad082]

i think its a ramp based scale where it decides to turn on rich and retard, i dont think its a flat 4.01v or higher trigger

what do you mean? i thought it would be a flat figure. when i did my turbo to cat exhaust it lowered the boost pressure i could run before it kicked in.

Edited July 17, 2006 by mad082

[rob82]

There is no Rich and Retard stategy that the ECU impliments when it thinks that you have wound the boost up. Its simply just goes rich and retarded at really high load points. Its all in the map!!!!!

[Sydneykid]

The ECU is looking for excess airflow compared to the engine rpm, so it moves to R&R mapping when that occurs. Could be at 4 volts or 4.3 volts, its rpm dependant.

cheers

[paulr33]

yeah as i expected, its a linear scale that follows rpm, ie: its possible to activate it at 3100rpm with 3.8v on the AFM but possible you wont activate it at 5400rpm with 3.8v on the AFM.

[mad082]

so you could say that it works off a percentage basis. once airflow reaches a certain percentage above what it should be for that rpm then it cuts in and changes maps..

[mad082]

and what sort of max power have people gotten from the stock afm? this would give a slight indication as to what sort of airflow it will take before it maxes out. (and this is where i want a max power figure, not a lecture about average power).

5 volts is the max voltage though, correct?

[paulr33]

5100mv is the absolute max. you can keep making more power but you run out of load points. as once you top 5100mv the load axis will never increase anymore. you could in theory make upwards of 260rwkw on the stock afm but youll find once you go past near 4800rpm its probably going to flatline across the load axis, djetro style.

the rule of thumb is no nore than 250rwkw, but its not like you can't make 260rwkw with it, or 270rwkw and so on, its simply that a rule of thumb for nice tuning.

i see mine max out frequently at 190rwkw on the stock afm, but at like 5500rpm

250rwkw will certainly work, youll just have less load points to play with

[rob82]

The ECU is looking for excess airflow compared to the engine rpm, so it moves to R&R mapping when that occurs. Could be at 4 volts or 4.3 volts, its rpm dependant.

cheers

What your describing is the TTP limit (airflow limit fuel cut) this is how alot of japanese ecu's work. They compare the g/s of ariflow vs rpm to a set maximum if it's above this then it cuts the injectors. There is only two fuel and two ignition maps for hi and low octane no others (apart form idle timing and a few others), so there is no such specific R&R map its just the overfuelled and retarded section of the ignition or fuel map.

Edited July 17, 2006 by rob82

[mad082]

They compare the g/s of ariflow vs rpm to a set maximum if it's above this then it cuts the injectors.

that what it feels like. because i find it kicks straight back in and pulls just as hard. if i'm in a low gear when it did it then it would wheelspin when it kicked back in.

[Sydneykid]

What your describing is the TTP limit (airflow limit fuel cut) this is how alot japanese ecu's work. They compare the g/s of ariflow vs rpm to a set maximum if it's above this then it cuts the injectors. There is only two fuel and two ignition maps for hi and low octane no others (apart form idle timing and a few others), so there is no such specific R&R map its just the overfuelled and retarded section of the ignition or fuel map.

Hence why we use the term R(ich) and R(etarded) mapping.

cheers

[mad082]

well that has given me the answers i was after.