Budget Fuel Controller for 1.6- SAFC, SMT 8, or?
 

BEFORE I get flamed
A: I have searched
B: Where is the engine management FAQ, or a FAQ for piggybacks?

1990 Miata/'92 Motor - Standard Greddy 5psi kit. Not intercooled yet. Stock injectors (94-97 Injectors on order). No BOV yet. Lets consider that it's up and running to be "phase 1". Definetly running rich which is OK; but I want a solution for a piggyback. Megasquirt is out of my price range.

I'd sure appreciate some help or advice on this. If there is something besides the SAFC or the SMT Controller I'd love to hear about it. Looking to be in the $150-250 range?? If you plan to answer all in acronyms PLEASE tell me what they mean; I learn quickly but I have to learn first!

Thanks

An MS1 r3.0* kit is $187. If you ask around, you can probably borrow a JimStim from someone here so you don't have to buy one. Cancel the order for the 1.8 injectors, and get a set in the 300-500cc* range from This List instead.

No matter what you do, I always recommend having a wideband AFR* sensor. The very cheapest one I know of is the JAW*, at $75 plus sensor.



Acronyms used:

*MS1 = MegaSquirt-1 CPU. r3.0 = Revision 3.0 circuit board. The CPU and the circuit board together form a complete megasquirt.

*cc = cubic centimeter (per minute). A meausre of fuel flowed through an injector when fully on and supplied at a standard reference pressure, usually ~45 PSI above ambient.

*AFR = Air to Fuel Ratio.

*JAW = Just Another Wideband, the name of a particular DIY wideband controller.

POWERCARD!






Seriously though. Save your money, or build your own megasquirt. What do you want out of this car?

Basically, I want a reliable setup. I don't plan on going any more exotic than an intercooler and 7psi of boost. I've read the limitations of the stock rear end on a 1.6; and I really enjoyed the car stock; so I don't want a turbo monster that is fun when it runs and constantly being worked on.

BUILDING a MS is a bit daunting for me; that's why I'm looking for a simple all in one Piggyback to control the fuel. Even on stock injectors I am running rich. I scored a deal on the 94-97 Injectors for $33; so I had to go for it....I also have a set of 460CC injectors that are plug and play.

Currently the car is running pretty rich; and a bunch of people swear by the SAFC. It seems like with a MAP sensor it is a relatively low dollar; reliable solution for my needs.

?? What exactly IS a wideband 02 sensor; and what does the controller do for it?

Is the Powercard suitable for a car making 5-7psi boost to get the A/F ratios right; or is it really only for NA cars? A plug and play solution for $200 is interesting. It won't do as much as an SAFC but it will keep things safe and reliable? Or am I missing something....

If you are 100% sure all you will ever want is just a intercooled 7psi greddy. All you need is the stock injectors a warlboro 190hp pump and a bipes for timing. Read through Brains FAQ post in the archives section.
Most of us that started with greddys went that way, it's a pretty common setup.

A wideband will tell you exactly how rich(or lean) you are and when. You shouldn't really be changing anything without it. You should also pickup a fuel pressure guage.

You know what an O2 sensor is in general, right? It tells you what your air/fuel ratio is.

The stock O2 sensor on your car is a narrowband type. They're called this because they are accurate only within a relatively narrow window that extends a few tenths on either side of 14.7:1. When you're running in a boost, a narrowband sensor can't tell the difference between 13.5:1 (which is way too lean) and 10:1 (which is way too rich.) It'll simply read "rich" the whole time. This shortcoming, incidentally, is one of the two reasons why most cars have an open-loop mode in the first place. When you go WOT, the ECU generally switches to open-loop and defaults to a pre-set fuel table that is engineered to get you somewhere in the 12s assuming a completely stock engine, intake, and exhaust.

A wideband O2 is linear across a very broad range. Most can read accurately between at least 10:1 and 20:1. So in order to accurately tune fuel for boost, you need a sensor that can accurately read in the 11:1 to 12:1 range, which is where you're going to be aiming.