I'm not sure exactly how the Jet V force works, but from the very limited description they gave on their website, it sounds similar to what Mazda did with the MP3's ECU. They advance spark timing and attempt to optimize the air/fuel ratio to increase power slightly. I'm a little confused by your references to having a 'richer' or 'leaner' fuel mixture, and whether one or the other produces more or less power. I've attached the definitions of stoichiometric combustion and air fuel ratio below. Basically there is a theorectically perfect mixture of air and fuel which results in perfect combustion. When you refer to running 'rich' I assume you mean more fuel than stoich, and when you refer to 'lean' I assume you mean more air than stoich. Running at stoich should provide the most complete combustion, and therefore the best power, so running leaner or richer than stoich would produce less power, not more. Running slightly leaner than stoich could improve your mileage slightly if you could achieve it without detonation because of increased heat. Running at exactly stoich air/fuel ratio across the entire RPM range would provide the best power, but is currently impossible to do. If you've ever seen an air/fuel gauge in operation you'll notice it usually bounces back and forth from lean to rich as the ECU responds to sensor inputs and adjusts the air/fuel ratio.

Stoichiometric Combustion:

Stoichiometric or Theoretical Combustion is the ideal combustion process during which a fuel is burned completely. A complete combustion is a process which burns all the carbon (C) to (CO2), all hydrogen (H) to (H2O) and all sulfur (S) to (SO2). If there are unburned components in the exhaust gas such as C, H2, CO the combustion process is uncompleted.

Air-Fuel Ratio:

Air-Fuel Ratio is frequently used in the analysis of the combustion process. It is usually expressed on a mass basis, i.e.
AF=(mass of Air)/(mass of Fuel)

 

Does this mean that we MP3 owners should be using 93 octane in our cars? I know in another thread posted we were talking about the hype of fuel and that our little cars run better on the lower stuff. I'm confused. I started out using 93 but since have changed because of the discussion in here, please help me out here.

 

Yes...you are correct about the most power coming when the engine is running at stoich rather than rich or lean....however....all cars dont naturally run at STOICH all the time. I would say that most engines run a little bit on the richer side to make for a smooth idle that will comfort the potential buyer. That being said, the PCM, by leaning out the fuel mixture could bring the engine closer to STOICH, therefore causing a more efficient burn and thus resulting in an increase in power.

This is my experience with engines...but keep in mind that I am fairly new to the traits of Mazda built engines.

 

Use what's recommended in your owners manual.

 

I read a post saying that an ECU isn't worth the $ if you're N/A. Don't for get about us with swapped engines. My fs-ze is not anywhere near potential because it's running on my stock ECU for my old 1.8L engine. I need something that will correct the fuel maps and ignition in all conditions, espically at WOT! Any "economical" suggestions? Corksport is trying to find a vendor now (or so they say). Superchips told corksport they need 4-6 months before they can get to it.

Derrick (corksport) told me that he didn't like Jet V and questioned their work for whatever reason.

I guess we could import the sport 20 ECU. Anyone know how to make or get a custom wiring harness?

 

Jeremy, have you installed an air/fuel gauge yet? I think that might be helpful to you with the FS-ZE swap to determine if the engine is running rich or lean, and under what conditions. Remember, you don't have access to the same gas the FS-ZE engine and ECU were designed for, so your ECU requirements may be different.


[QUOTE]Originally posted by eeterp
[B]I read a post saying that an ECU isn't worth the $ if you're N/A. Don't for get about us with swapped engines. My fs-ze is not anywhere near potential because it's running on my stock ECU for my old 1.8L engine. I need something that will correct the fuel maps and ignition in all conditions, espically at WOT!

 

Greddy917

Most modern automotive engines run on the rich side of stoichiometric. In addition to smoother idle, as Greddy917 mentioned, running rich also reduces knock. By programming a rich fuel curve, the engine operates under safer conditions. Even when reprogrammed, the curves are still typically rich, but not as rich as stock. Becuase of this, conversations about running lean or rich become a bit skewed. "lean" is still on the rich side of stoich, but leaner than stock.

 

I was referring to optimum engine performance. If the stock 1.8L ECU works, I'm certain the FS-ZE ECU would also, but it still may not get the most out of the FS-ZE engine running on US premium gas. The knock sensor is definately a benefit, but if you're ECU ignition curve is causing the engine to detonate, and the knock sensor retards the timing to compensate, you're obviously not getting the most performance out of the engine.

 

I'll look into getting an air/fuel gauge but, how do I determine if I'm rich or lean. Do you need to input stock settings, does it read them from the stock ecu, or something else?

Do you know how to get a custom harness? I may call mazdamotorsports because they have a few harnesses. I just don't know exactly what each one is used for.

 

The air/fuel gauge reads the voltage from the O2 sensor. The gauge itself has a mark in the middle for stoichiometric, with rich or lean on either side. The gauge normally moves back and forth from rich to lean very quickly as the ECU adjusts for sensor readings. What you're looking for is excessive movement towards rich or lean, or extended periods of time in either condition.

 

I agree Air/Fuel guages are typically inaccurate, however, they are good for noticing changes, operating outside the norm. As Eric F had mentioned, running too long on one side or another. I've never priced an Exhaust Gas Temperature (EGT) gauge, but assummed they were rather costly (I don't know why I assummed that, it's just another temp guage). Definitely worth it if you plan to do much tuning though. I don't see much utilitity with either gauge if you don't have the ability to modify your A/F ratio through fuel system controls.

For those that plan on getting an OBDII scanner, there is an A/F reading on AutoTap (don't know if it's on the OBD-2 software). On my other car at least, the A/F displayed is what the computer is shooting for, not actual. To get an A/F reading that the ECU is recieving look at the 02 sensor voltage. . . again 02 voltage not as accurate at EGT.

 

I agree... I had BOTH on my GVR4 and would recommend to use both. Of course... if you are NA I think that it is superflews. The EGT will be more expensive and in order to use/install it, you will have to drill a hole into your exhaust manifold...then tap it to match the NPT on your exhaust temp probe. Placement of the probe is crucial too for an accurate reading. The A/F guage will just tap into your O2 sensor wire...no biggie in comparison. For a boosted car these are a MUST.
I must admit...I see both these on many NA Hondas...it pisses me off because I know that they are for show not go. Honda racers...go figure

 

So after all that's been said, should I get the chip or not?

 

If you've got the money, go for it! Hell, it MAY be worth it to you. Let us know what you think. Maybe the WOT thing isn't all that bad.

 

I am definitely interested to hear how you car responds to the PCM if you get it...I am also considering buying it.