voidhawk

iTrader: (20)

After installing new injectors and getting all the fuel trims dialed in, I also updated the fuel maps to get to my desired AFRs. A large portion of the fuel map is a block of 14.7, does that value have to change with the new injectors as well?

bambooi

iTrader: (6)

No. Don't you have a wideband? You can confirm that.

GRNCT9A

iTrader: (1)

your map looks funny to me, the 14.7 is probably fine, do you have a wideband? Are you running meth or E85? Why does your map at WOT start out rich and lean out alot?

voidhawk

iTrader: (20)

I'm using the OEM O2 to tune the AFR (no wideband), it works pretty well if you have a good starting map that was fairly close (tuned by somebody who does have a wideband). I guess I don't really understand why the 14.7 area is different from the rest of the map - is that where the ECU runs "closed loop" vs. "open loop"?

My boost peaks 26psi around 3500 rpm and then drops off to 22psi up top, so I run richer in the peak boost area to prevent knock. From what I've learned so far, "heat = power" and "too much heat = knock". Heat comes from compression (boost) or lean burn (EGT/AFR). Since the boost drops towards redline, I can get away with adding more heat by running leaner.

I'm still climbing the learning curve though ...

nothere

iTrader: (23)

the 14.7 is closed loop area, unless you defeat that function. if you run open loop only you can use that area

voidhawk

iTrader: (20)

ok that makes sense. Do you know what values (rpm, load) the transition happens at? I rescaled my map to get finer control at peak boost and higher max load and I'm wondering where exactly the ECU switches over ...

voidhawk

iTrader: (20)

OKay now I'm lost again ... take a look at the attached log, this is me cruising (in closed loop I presume) and tapping the throttle just enough to get out of vacuum on the boost gauge, and it knocks like crazy! Since I can't change the AFR, it should be too much timing but 11 deg?? Any idea what may be causing this ...

Wicked E

iTrader: (26)

My guess is lean spool?

jrohner

+1

voidhawk

iTrader: (20)

Thanks guys, I didn't think of that. I've disabled lean spool using the periphery bit now, I'll let you know if that fixes it!

fostytou

iTrader: (15)

I'm not sure how using a narrowband to tune your AFR "works" at all. It is in no way an accurate representation of any AFR other than 14.7

Best of luck not blowing up something, you may want to have your tune checked out when it is complete. $150 wideband purchase > $6k Motor purchase.

Don't take that the wrong way, I'm trying to help you....

voidhawk

iTrader: (20)

hehe ... I was waiting for some smarty-pants to get on my case for that. It all depends on how much you know. Narrow band O2 sensors read volts as a function of both AFR and EGT when away from stoich (14.7). Take a look at this plot to see what I mean.

The different curves (A,B,C) are for different EGT values (500,750,900), so if you know what your EGT is (I have an EGT gauge) than you can pick the right curve and get AFR from the narrow band. This is an approximation, but it's a good one.

In the end what kills an engine is either knock or heat, and you can monitor both of these without a wideband. I've been tuning my car this way for a month now doing almost a hundred pulls, and the engine lives, and makes more power than before. Of course, a wide band is the better tool, but I like learning / trying new things and I'm confident that I know what I'm doing ...

fostytou

iTrader: (15)

Even with knowing the EGT there is only a ~.02v difference between 10.3 and 13.2 AFR on that chart. That is not anything near the realm of what I'd call "accurate". Frankly, at that point I'd say you are wasting your time even logging that item. That amount of voltage could easily be gained or lost by noise.

While I agree with you on the point of knock and heat being the real detriment to an engine's life having a good AFR is a great point to both power and safety. There isn't much to be said about "tuning" if you are taking a big chance at removing both. In any case, just because it hasn't blown up yet doesn't mean it won't the next time you step on the gas.

voidhawk

iTrader: (20)

I had the same reservations before looking into this in detail, but looking over Aaron's (English Racing) shoulder while he road tuned my car this way got me curious, and learning more about it convinced me otherwise. The graph above is a generic to illustrate the point, this one (below) is specific to the O2 sensor in the Evo and in the region of interest:



The three points is what I tune my car for (spool, peak, everything else). Using this method I can push 27 psi on 92 Oct without any knock @ 800C EGT. If my AFR was as far off as 13's as you suggested, this would not be possible. Also, the O2 voltage is not noisy at all, here's a log for you (not a perfect tune yet, but you get the idea):

voidhawk

iTrader: (20)

you were spot on - disabling lean spool fixed the problem . I'm still trying to figure out how to set when the ECU transitions from "closed loop" to "open loop" though. I've found 4 tables in ECUFlash that seem to have a bearing on this

1. Open Loop Load #1 & #2
2. Open Loop Throttle Low Load & High Load

It looks like the value for "Open Loop Load" shows the load value that must be met (or exceeded) for the ECU to go into open loop at a given rpm, is that correct? What is the difference between #1 & #2 though (they have different values in my ROM from a previous tuner)? Also what is the purpose of the Open Loop Throttle tables? Thanks for all the help guys ...