Ted DiBiase

Are there any companies that manufacture aftermarket/performance MAF's or intake manifolds for the 2nd Generation RX-7's? Any feedback=greatly appreciated.

Thanks

NZConvertible

Nope.

mprime

Ditto on Nope

ka8legend

Instead of using an afm can we not use a MAP sensor to feed similar information to the ecu. The series5 ecu reads linear voltage from the plunger type afm so it might just work, no?

NZConvertible

No, airflow and manifold pressure are completely different to each other and require quite differerent programming. To use MAP sensing with the stock ECU, you need a $1200+ HKS VPC, but they were only made for S5's.

ka8legend

So you're saying that the amount of air flowing thru that afm is in no way proportional to the amount of vacuum in that manifold.
My reasoning was that if you floor it (WOT) in first gear, map sensor and afm should both put out that same voltage signal.

NZConvertible

That's exactly what I'm saying. Think about what's happening in your engine. When you floor it, manifold pressure goes straight to just below atmospheric for an NA, and almost straight to max boost for a turbo. It basically doesn't move from there until you lift your foot. But the revs keep rising, so the airflow must also be rising. So the two signals are not proportional.

flubyux2

there are manifolds. but only for carburetor set ups. mazdatrix has some, for example.

ka8legend

So how does say, a honda civic, go about managing air flow w/o an air flow metering device, but with just a MAP sensor and other non pertinent devices like air & water temperature sensor, etc. The honda fsm saids a lot about how the ecu gets its primary signal from the map sensor to control fuel duration but you seem to diminish the importance of the MAP concept. Please enlighten

RETed

A MAP sensor can be used as a load-sensing sensor, but it's output versus load is totally different than a MAF type system.&nbsp You can do a conversion, but are you going to program in the transfer function to "fool" the stock ECU?&nbsp You're better off going with a stand-alone EMS that already does this and program from scratch.&nbsp With EMS's down to about $1,000 (Haltech - Microtech is down to $500!), messing with the stock AFM and/or MAP retrofit system is a total waste of time, IMO.




-Ted

NZConvertible

Because it's designed to. The ECU uses manifold vacuum and rpm to calculate fuel requirements. This is exactly the same as how Haltech and other programmable ECU's work. Manufacturers use airflow meters more often because it’s a more accurate method of determining fuel requirements, which makes it easier to achieve economy and emissions targets, but some power is lost due to the restriction of the AFM. The point here is the two methods require totally different programming of the ECU. So there’s no way you can just swap from one method to the other with the same ECU. Otherwise HKS wouldn’t sell many VPC’s would they?!

ka8legend

You know I was dreaming of the day when ems prices would drop like the way my $1800 pentium system was depreciating; I would only be paying $200 for those old haltechs
Now that you mentioned it, the day has arrived. just gotta bag a few more lunches for the next two months.