Thread: Tuning a Calum B13RT... a tuning noobs first impression

Ever since I learned about how fuel injection works I've been wanting to try tuning a car.

Yesterday I got what I wanted.

Dudeman had just installed one of snickers headers. Because of the fact that it only had one O2 bung, which was going to be used by his wideband, he decided to delete the factory O2 sensor.

The car started up and idled with an AF ratio between 12.1 - 13.1, too rich! Nissan DataScan provided us with a maptrace feature which allowed us to figure out which cells were being accessed. Changes were made to the cells used at idle (and all neighboring cells) with TunerRT Pro, and were uploaded to the Realtime.

After about an hour of messing around, we got the idle to be a pretty rock solid 14.7 - 15.2. We haven't decided if we are going to keep this target AF ratio, but we were really happy to see that we could actually have an effect on how the motor ran.

For the people out there who are scared to try tuning there car, don't be! If you use common sense, and dont do something like advance all your timing maps by 20*, or set your high rpm fuel map cells to 0, I don't see how you could mess anything up.

If your tune doesn't work, you can just load up whatever was on your ECU to begin with.

We're going to street tune the fuel map later today. 2k-4k RPM reads about AF 12.5 - 13.0 and needs to be leaned out.


We were going to ask Calum and consult some of our Carrol Smith books, but if you are reading this and you know the answer please chime in.

On an SR20VE:

1) What's a safe AF target range for idle?
2) What's a safe AF target range for 1500 - 4000 rpm cruise
3) What's a safe AF target range for 2000 - 7500 rpm WOT

My inclination from what I have seen people aim for here and on other forums is

1) 14.7 (up to 16)
2) 14.7 (up to low 15s)
3) 13.5-13.7 for a NA car

I've been struggling with these questions as well, and have done a fair amount of tuning in the context of trying to pass emissions testing. If you look at the original fuel map, any cells that were designated as closed loop (idle and light throttle) obviously should be targetted for 14.7 or maybe a little leaner if you want.

For WOT, 13.5-13.7 strikes me as probably a bit lean. Not necessarily unsafe lean, but my experience has been that more power is made at 12.9 to 13.2. But I'm still learning too, so don't take this as gospel -- just my thoughts at this point.

Also, as you are tuning, remember that the ECU makes adjustments to the injector pulse duration based on rapid changes in TPS voltage. So you have to wait for that enrichment to run it's course before you can see the AFR that is really being delivered by the map value after opening the throttle.

Idle 14.7 but it's going to jump around, cruise should still be in the 02 flagged area so you should be 14.7-15.X but going back to 14.7. If you floor it from 2k to redline it's going to cross thought the 02 flagged parts then hit your WOT map. I tune to 13.0-13.2 a/f @ wot. Snickers says he goes richer to mid 12's I think.

This is an old map trace I did years back with nissan datascan. It's not like tuner pro where the low are RPM's are at the bottom.

Good info, thanks. But remember I have my o2 disabled. So closed loop means nothing anymore.

We ran into an annoying problem where we had the idle pretty good at 15-16, and sometimes it would randomly go to 11afr at idle. I notice this every now and then, and it is super weird. We have the entire bottom area reduced to 15ish, so we have no clue why it sometimes goes so rich. It is not in a cell or even adjacent to a cell that is rich at all.

Dudeman

Are you interested in keeping the catalytic converter operating properly?

As for the 2,000-7,500 rpm WOT A/F ratio I'd stick somewhere around 12.8:1 on an N/A engine for best power.

He's not using a cat. So no.

Since we now have peaked the attention of some knowledgeable folks. I meant to ask, when I load up the map trace, inputting Calums parameters gives a funky looking map, with the rpms only going to I believe 3200. I have tried this many times now with the same result.

Loading up the sr20det map that is included in NDS seemed to work fine. And no I didn't accidentally use the timing maps for fuel

Any explanation?

What program are you using for map trace?

NDS

Dudeman

You shouldn't have to input the numbers for the newest version. I'll have to look at my laptop later and I can tell you what numbers to put in.