AFC question

[Griffin]

Okay so heres my question - does anyone out there with an AFC have a scan tool and if so do you know what kind of fuel trims you run normally. Heres why I'm asking:

I've been reading up on AFCs - and it seems that basically they fudge the MAF numbers to try and get the ECM to richen the fuel curve. The problem is I don't see how it could possibly work on a long term basis unless it only does it every now and again....

See if the MAF signal is wrong the O2 sensor will tattle and the ECM will adjust the fuel curve back to where it ought to be and eventually set a CEL. The only way I could see around this is to actually give a bogus O2 reading back to the ECM to tell it all is well, but all I see on the O2 side is a take off not a splice in... so I'm wondering how it could possibly have any long term affect on the system aside from to cause high negative fuel trims and/or lean codes... Or does it actually condition the O2 sensor waveform somehow as well?

Griffin

[GTS LAID]

i just read what they did with the matrix... and i think they used the TEC II Not the SAFC... but the TEC II just took over those functions.. they tapped the wires then unplugged them from the ECU... it was still adjusting.. but the signal just never made it...

I do remember that you have to do some cutting for the AFC... maybe thats what it does...

actually forget it.. the more i remember ... it works by augmenting the stock charts... so thats not even a possibility...

good point though.. it might explain why when people hook it up to a CAI they see the CEL ... they stock ECU must be trying to compensate back using the O2 sensor data and its doing more than 20% for long periods of time...

any AFC experts out there.

[Griffin]

good point though.. it might explain why when people hook it up to a CAI they see the CEL ... they stock ECU must be trying to compensate back using the O2 sensor data and its doing more than 20% for long periods of time...

any AFC experts out there. [/B][/QUOTE]

Thats exactly what I'm looking into.

The AFC cuts the MAF sensor wire - it merely Ts into all the other stuff. So basically all it could be doing is lying to the ECM about how much air its getting so the ECM will give more fuel... which will work for a little while but the ECM is going to just go ahead and correct the fuel trim slowly to compensate - kind of the exact opposite of whats happening with the dirty MAFs and teh lean codes.

Griffin

[DaksGT]

Griffin you should check out the HKS super AFR
I had the SAFC and swapped it for this unit, its much better in performance and it offers many more usefull functions than the SAFC.

Air/Fuel Ratio Correction Function
Controls air/fuel ratios through airflow meter or pressure sensor
Range - 50% rich to 50% lean from the factory baseline settings
Output can be adjusted in 1% increments
Eleven points of adjustment between 650 and 8000 rpm, these points can be arbitrarily moved in 50 rpm increments
Response Correction Function
Engine response can be adjusted through airflow meter/pressure sensor
Range - 1m/sec to 100m/sec
Six points of adjustment between 650 and 5000 rpm, these points can be arbitrarily moved in 50 rpm increments.
First in the industry to offer this function in a simple airflow correction device
Idle Correction Function
Idle mixture can be adjusted 50% rich to 50% lean in 1% increments within the idle range (650 to 1500 rpm) from factory baseline setting
This adjustment is made independent of the other eleven points of mixture adjustments in the air/fuel correction function
Electronic Idle Stabilizer Function (EIDS)
This automatic function prevents engine stalling or stumbling in some airflow meter vehicles which use blow-off valves discharged to the atmosphere when throttle is released
Base of Adjustability and set-up
This device is very simple to set-up and adjust
The head unit is adjusted through three control knobs
HKS recommends tuning for this device be done on a chassis dynamometer with use of an accurate air/fuel ratio measuring device


http://www.alamomotorsports.com/hks_safr.jpg

[Maelfyn]

All I gotta say is I have i/h/e and safc. I have had CEL for like 8 months now. Toyota can't figure it out.

[BoyRacer]

Originally posted by Maelfyn
All I gotta say is I have i/h/e and safc. I have had CEL for like 8 months now. Toyota can't figure it out.

thas weird. i dont have the header on yet, i hope mine doesnt give me a cel. the only time i got the cel light after the s-afc install was when i messed with the flap. :) that F*** the whole car up though.

[DaileyDog]

DAKS: Couple questions:

1. Who tuned it for you?

2. Where did you intall it in the car?

I'm in the market for these and am sort of like a lot of other people: a little unsure of which one (SAFR or SAFC) to go with. I like the HKS a little more and I'm curious about any other info you can offer from using it.

Thanks.

Mike