Street Tuning on a Narrowband and a sanity check
 

Am I right in thinking that street tuning on a narrowband is a bad idea? Will a known good stock 1.6L motor VE table be adequate for driving without a wideband? The way I'm understanding it is the MS reads MAP and RPM, checks the VE table to see how much air the engine is pumping (won't be over 100 for a naturally aspirated motor) and then calculates how much fuel is needed to reach the target AFR. Without a wideband, however, I won't be able to see how accurate the VE tables are. So really, how safe is it to get a 1.6L Naturally Aspirated VE table and plug it into my MSQ and assume it's right? If I have to pay $90/hr for dyno time I might as well just spend $100 extra for the wideband.

As far as the sanity check goes I am going to get a wideband soon when I do some serious tuning. Since I'm using the megasquirt I don't need the narrowband, right? I can just remove it, thread in the wideband (the threads should be the same OEM vs LC-1, right?) hook up the gauge and connect it to the MS? I don't see why not. Will I need to get the wideband controller in addition to the gauge?

These are probably basic questions, but I've done some searching and couldn't find adequate answers. I'm about to start building my DIYPNP so I can learn how to tune the miata before I slap a turbo on.

P.S. anyone have a good base map for a naturally aspirated, stock 1.6L? The diyautotune map is for a 1.6L with a BEGi S3 turbo kit. I don't think the VE would be the same up to 100% MAP kPa.

I tried autotuning on narrowband and it sucked. So I don't recommend it.

You won't need a narrowband once you get a wideband, unless you're running piggyback or something stupid like that.

The diyautotune maps are fine. They are scaled to 250kpa I believe. Your naturally aspirated engine will only use the bottom 40% of the map up to 100kpa.

LC-1 *IS* the controller.

Won't the VE table be skewed? The turbo will still be spinning with the wastegate fully open providing extra air flow to the intake. I might have this all wrong though... I've never tuned a naturally aspirated car so tuning naturally aspirated MAP pressures is going to take some getting used to.

So I can hook this kit up to both the provided gauge *and* MS?

sanity and narrowband. lolzzzzzzzzzzzzzzzzzzz

Open/unhook the waste gate and tune up to 80kpa on the narrow band. When you're ready to have fun in boost order a wideband confirm your readings for what you've tuned and then start tuning up to wot. Then connect the waste gate and start tunning in boost. A LC1 on the narrow band location is a no no, you want it right in front of the cat by the tranny. Don't be a -----... get a wideband and tune right from the start. Oh and a wideband is ~200 bucks+shipping.

I am naturally aspirated, I won't get to turbo the car until late summer at the earliest.

Could you explain why the narrowband location is bad for the wideband?

Too hot.

Easiest thing to do is leave your narrowband in place, don't mess with it. Drop the midpipe and have a bung welded on for the LC-1 as suggested, right before the flange for the cat. Put it on top, and it's a straight shot for the cable up into the cabin underneath the shifter boot. You can stuff the LC-1 itself into the radio compartment area, there should be plenty of room.

I've done it with a narrowband and got pretty decent results (as confirmed after installing a wideband). But it does take a long time and is a pain in the butt.

Anythhing under 14afr and over 15.5 and you're guessing. You've got that narrow window to tune in.. Long story short you can tune the cells within those areas however wot (NA) that requires 13ish afr... you cant tune those with narrow band.

That's not correct. You can tune with a narrowband without "guessing". Your NB can tell you when you're at 14.7. From there, it's simple math to adjust your VE table to your target AFR. Just divide the actual AFR (14.7) by the target AFR (say, 13.0), and multiply by your VE. I use this on the dyno and it's very effective. TunerStudio or MLV will do this automatically.

Justin that is very interesting. Great way to use narrowband data to build a ballpark boost map!! Brilliant!

So let me guess this right, you have money to waste on a dyno guessing what your afr is yet you're being a cheap ass to spend 200 bucks on a wideband?...200 new that is.

I will get a wideband eventually. Not being able to use the narrowband sensor location is a bummer, since I'll probably have to pay $50 to get a bung welded onto some pipes that I will likely throw out anyways if I want a wideband when still N.A.

And dynos will have a wideband to shove up the exhaust pipe. I wouldn't be guessing the AFRs.


Sounds like a good method.

I'm not saying that I use a narrowband on the dyno. Like he mentioned, any dyno will have a wideband for you to use.

Bah this narrowband tuning is no substitute for buying a wideband BUT

the maths could come in very useful when tuning stock cars that have band aids etc or limping home blah blah

one problem though is that volumetric efficency does not scale linearly with boost.

same way as I tune my maf setup megasquirts.
actual afr vs commanded afr. of course I don't have to deal with VE table.

I should mention that I mostly tune normally aspirated cars, so I don't have much experience doing this on a turbo'd vehicle.