Cheap & Simple Fcd For Electronics Buffs

[666DAN]

Found this while looking around on the net, great for those who like to mess around with electronics and cars.

http://www.graphics.cornell.edu/~v/fcd/

[WogsRus]

Skylines use air flow protection comming through the AFM, so possibly to adopt something like this, but who knows.

[666DAN]

Yeah you just use one of the 5v sensor power supplies on the ECU as a reference, then run the AFM output through it to get your clamped voltage. I'm making one for my car at the moment.

[WogsRus]

tell us how it goes, How will the car deal with the leaning out of the fuel mixture?

[666DAN]

As you can see my car won't be bothered by a bit of leaning

I'm actually going to set the voltage clamp at 4.9V so I don't lose too much resolution on the factory map. The car is going in for a full ROM tune anyway, but the turbo maxxes out the AFM at fairly low boost pressures. So with the FCD I'm going to get it tuned for around 16psi and see how it goes.

[WogsRus]

yeah i had to leaned mine out heaps, pulled 207rwKw with an SAFC II, 12 psi and some timming. LOL. I started with 147 i think, took 6 hours to get that figure.

[mad082]

rich and retard isn't just at 5v on the afm. you can get it at 3v. when i got it it hit hard at about 3000rpm when it had just come on boost, but if i backed the boost down less than 1 psi it would rev all the way to 7000rpm without hitting it.

it is caused by the ecu running out of mapping for that amount of air at that rev range.

i would only ever get it at low rpm where the car would die for a split second then it would come back to life, light the tyres up and pull as hard as normal up to redline.

[666DAN]

My ROM has already had the R&R tuned out of it (all cells have reduced fuelling and increased timing with respect to the factory settings) the FCD is purely to stop the ECU shutting down at 5.1v (where the map ends for the AFM) as it currently does.

My tune didn't lend itself to the upgraded fuel system and turbo, that's why it's rich, previous was running nice flat 12.5:1 AFR on 12psi with the stock turbo.

[WogsRus]

If it running out of map, why not get a biger AFM?

[mad082]

a bigger afm doesn't really help if you are running out of maps.

[666DAN]

If it running out of map, why not get a biger AFM?

A) I'm a cheap-ass

B) I can tune around it easily enough