I know this I a turbo forum but I'm guessing some of you have phased your projects similarly to me so maybe someone here can help: ECU first, turbo later.

My question: Does anyone have an air:fuel ratio map for an naturally aspirated 1.6L NA? I have a naturally aspirated '91, which will someday get a turbocharger added to it. In the meantime I've installed a Megasquirt PNP ECU.

While his car is turbocharged, Joe Perez gave me an air:fuel ratio map for a naturally aspirated car he that had lying around, presumably this was from his car before the turbo was added. Anyway, while the map seems pretty safe, he admits that it may not be ideal.

I'm using Tuner Studio and VE analyze to tune the volumetric efficiency and was wondering if anyone had a AFR map for a naturally aspirated 1.6L car that they could share?

Why do I ask? Well, the car is just running a little funny and frankly, I don't know what I'm doing. So I'm starting with the one thing I have half an inkling about. I don't actually know that a different AFR table will help. Maybe I'm doing the autotune wrong an the VE table is bad but I can see what I could be fouling up there. Maybe the spark table is off.

So I guess the even bigger question is whether anyone has a primer for tuning a naturally aspirated miata - a step by step set of instructions of what to do and what to look for. Thoughts? I'm here witha stack of bookstand clearly over my head.

Thanks,
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Ben

'91 SE #3147/4000 (BRG)

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Have you tried diyautotune's base map? Download and burn that for your '91. I don't know if it comes with a AFR target table, but it's worth a shot. Use that spark map, and don't change it what so ever. Tune only fuel for now until you know what you're doing.

When my wastegate disconnected (bandaids) the stock ecu ran a dead steady 14.7afr. I'm not saying that's ideal, but you don't need to go too rich with an N/A engine. What's Joe's target table say for atmospheric pressure?

 

something like this will probably work:



blended with this:




I'd take the bottom map, and blend in the top map above at the 4600 mark and above. You can keep it lean in lower load cells in higher RPMs where you cruise, but when you get on the throttle, so between 70-100 and above 4500RPM you want it to look like the top map where it gets richer by redline.

 

Thanks you guys. I'll have a look, do a little experimenting, and let you know what I learn.

Ben

 

Here's the AFR Table Joe gave me and the one I've been running. Any first impressions?

Thanks,

Ben

 

BTW Braineak, your AFR tables have more cells than mine - less interpolation I guess. Is there a way for me to add cells in Tuner Studio?

Thanks,

Ben

 

I'm also curious about why the load numbers in your base case are all "normal" integers, while your custom table has some of them tweaked. Just trying to understand what people are looking at and why.

Thanks,

Ben

 

Im running ms3.

 

High 13/low 14:1 AFRs melted pistons on my N/A 2001 motor on track.

 

at WOT above 80 kPa... which is where i said to make it richer.

I'd try something like this:

 

why wouldnt 14's in the 100kpa range melt engines? Surely you dont want the OP to tune for that...

 

Braineack,

I like your AFR table. Interestingly, one of my cars I have ms3x setup. The base table is similar to yours.

 

(zack morris's phone)

Goes lean fast.. might struggle for power is high vacuum areas