AFC Neo for simple fuel management

[eTiMaGo]

To continue our old discussion of approaches to tweaking the AF maps...

To recapitulate, the ECU has two distinct operating modes: Closed loop and open loop.

Closed loop uses the AF sensor in the header in order to make adjustments to the injectors duty cycle to keep the exhaust gases at a normal mixture. Tuning the AFR in this mode is rather difficult but could potentially be done by intercepting the AF sensor's signal and reporting to the ECU that it is leaner than it already is.

But what's of interest here today is open loop tuning. From PK's data logging runs, we saw that the ECU seems to go to closed loop mode once the throttle reaches about 75%. When it's in closed loop, the ECU uses a fixed internal map, and calculates the injectors duty cycle based on RPM and MAF sensor signals. Thus in theory it is possible to make adjustments to the MAF signals in order to tweak the resultant AFR. This seems to be the way Blitz's fuel controller for the supercharger kit operates.

So what would be useful is a tuning tool that can adjust the MAF signal only once a certain throttle percentage has been reached. I've done some looking around and Apexi's AFC Neo seems to fit the bill.

http://www.apexi-usa.com/products/?id=5347

Two adjustment modes: Hi throttle and Lo throttle, with the ability to select the throttle percentage for each mode (i.e. we'd set Hi Throttle at 75% and make adjustments there, while leaving the Lo throttle mode at default unadjusted values)

up to 50% signal adjustability, plenty of headroom

It also has a mode to cancel out the wrong readings that a MAF might give when you close the throttle and blowback occurs, I think someone mentioned getting a CEL at a certain time because of this

Problem is, the device costs about $400, which is a bit hard to justify compared to just dropping in some bigger injectors. But, it offers a degree of adjustability, even for the non-turbo'ed ones with a lot of other bolt-ons.

[cali yaris]

Good find Thomas,

$400 is cheaper than $120-each injectors, until you add the tuning cost.

The two largest hurdles with our projects, IMO, is "who can tune this thing for me?" and "is it plug 'n play?"

[eTiMaGo]

Originally Posted by cali yaris

Good find Thomas,

$400 is cheaper than $120-each injectors, until you add the tuning cost.

The two largest hurdles with our projects, IMO, is "who can tune this thing for me?" and "is it plug 'n play?"

true true... but with a wideband (which you should have anyway), you could probably self-tune it little by little. Like I said, we don't need super adjustability for a smallish project, just an easy way to dump more fuel when required.

I have not found an actual wiring diagram but it seems about as plug and play as the Blitz fuel controller, not a whole lot of wires to splice...

[mrbond]

So, if I'm reading all of this correctly, this would be a way to tune the A/F ratio for both boosted and non-boosted cars? So those of us with all bolt on things like a CAI, 1ZZ TB, header, pulleys, and header-back exhaust would be able to tune the car to optimize HP gains for each modification? If so, that's not bad at all for the price...until, like Garm says, you get to the tuner. But even so, still not bad.

[eTiMaGo]

Yes exactly... I only have a narrowband AF gauge but if it is to be trusted, I can see my car runs very very rich at WOT, down to 11:1 sometimes... there's certainly a few horses to be gained from leaning that out a lil!

[mrbond]

Wow, then this is really an excellent find!

[eTiMaGo]

now who's got $400 to give it a try?

[mrbond]

Well, as for me, this would have to wait till about december (christmas money, etc). Now, Thomas, would one be able to feasibly tune their own car using a wideband gauge?

[eTiMaGo]

heh... I certainly don't know enough to give you any specific instructions

[mrbond]

Well, we'll just have to wait and see, then.

[eTiMaGo]

well here's a good read:

http://www.diyautotune.com/tech_arti...squirt_ems.htm

[Tamago]

AEM FIC is cheaper

[johnsmith12709]

Yes you are absolutely correct.....
..........

Originally Posted by eTiMaGo

true true... but with a wideband (which you should have anyway), you could probably self-tune it little by little. Like I said, we don't need super adjustability for a smallish project, just an easy way to dump more fuel when required.

I have not found an actual wiring diagram but it seems about as plug and play as the Blitz fuel controller, not a whole lot of wires to splice...