I currently have a Mugen ECU with I/H/C/E and do not plan on doing other mods in the future, so I will be keeping this ECU. I will be going to the dyno to have the cam gears tuned, so I was thinking if it would be WORTH IT to get some light tuning device such as a vafc and/or fpr...

-since the Mugen ECU already runs rich I thought vafc without fpr would be ok, I understand the vafc isn't good at adding fuel, but since this ECU already runs rich I wouldn't have to add much if any fuel...right?

-but then there are people who say this ECU likes more fuel...so in that case the fpr might be enough...WTF?

So what should I do? Get a vafc or a fpr or both? Or forget both because it would yield minimal gain with the base map I have?

 

Just get a vafc and not the fpr since it already runs so rich.

 

^^^ what he said

 

but why do people suggest upping the fuel pressure with the Mugen ECU? It's a controversy that I don't understand...

 

Alot of people like V-afcs and a V is ok if you...

(1) Have a good Air fuel gauge (good= is a AEM, Greddy....one that actually tells you the air/fuel ratio, and not just flashing lights like auto meter)

Here is how a V-afc works...it takes the input from the TPS and the input from the map sensor and "tricks" it into thinking that it is a higher or lower variable than what it really is. BUT the real lame thing about a V-afc that alot of people don't know or don't tell you is that it does not self adjust itself to climate and pressure changes that change your ecu maps! Your Ecu accounts for these things, and when the climate, pressure or elevation is different from the day you tune it, it will NOT be at the same level (but the V-afc will be)!!! It could run much higher or much lower than you want it to i.e. you will either be running richer or you will run leaner!

This is why you need a very good air/fuel gauge so that you can adjust it on the fly and have an idea of how rich or lean you are running! If you are picky it becomes a constant battle DAILY to keep you car running at the correct air/fuel you need!

What mods do you have? The Mugen ecu is tuned for a Mugen exhaust, air box, header...If you don't have these things or similar parts then you are probably runnin too rich as it is, and Hondas (N/A) tend to run better when closer to "stoich" (14.75 "even" air/fuel mixture).

I personally would dyno the car with the Mugen ecu by itself, and see where you are at first and the go from there! But that is the 411 on V-afcs. Many people use them as Vtec controllers and displays (rpm, throttle...) and set them to "0" properties. If you set it to "0" it will run exactly how the ecu wants to.