Travis R

I know the question has already been answered but I thought I'd throw this out in case there was still any confusion. Note that all of these methods require a TPS (throttle position sensor), IIRC (if I recall correctly).

MAF - mass air flow sensor. Usually a hot wire or screen. The computer measures the resistance across the wire. The resistance changes with the temperature of the wire. When the air passes by the heated wire, it tries to cool it off... so the computer can tell, by measuring the voltage drop, how much air is going into the engine. The cool thing about this setup is that it also takes care of changes in ambient air temp. If it's hot outside, the hot air won't cool the wire as much. The downside is that it doesn't react super fast... it takes some amount of time for the wire to heat up and cool down with changes in air flow.

AFM - air flow meter. On Mazdas it's a "flapper door" where the air coming into the engine moves a door out of the way. And the computer knows how far the door has opened. the bad thing is that this method doesn't account for air temperature, and reacts even more slowly than the MAF.

MAP - manifold absolute pressure. I like this one the best. The pressure inside the intake manifold (down stream from the throttle) is measured. The pressure is a very good indication of the load on the engine, and reacts almost instantaneously with changes to the throttle. The only bad thing is that it can't tell changes in outside air temp, so it's best to have an air temperature sensor somewhere in the intake tract. GM actually makes a MAP/Air Temp combo sensor, but I have yet to see it work on anything other than a GM vehicle.

Good luck

1Revvin7

Travis R :bigthumg:



I made a mistake, a TID is only for a turbo Rx7, I read your name real quick and thought you had a 4port turbo motor, hence the "Rx7 13B 4", anyhow so you just want a hard intake pipe going from the afm to your TB(throttle body)? There are some companies that make them but they are ridiculousy expensive, I have heard that some people use ones designed for civic, and they cut them to make them fit. Waste of money though, the amount of $$ doesn't justify the power(1-2hp maybe)

RX7 13B 4 UR AZZ

any one got any info on thoes hard pipes? I want it mostly for some nice bling bling of chrome hard pipes. :bigok:

i could just go to a muffler shop and have them bend me a few pipes. I was also thinking can the AFM bemoved closet to the tb?

1Revvin7

I suppose you can move the afm, just make sure it sits level. You could have a shop make you one, that would be cheapeast probably.

Travis R

I think moving the AFM closer to the TB might be a bad idea. If the AFM is already slow to react to changes in air flow, having it closer to the TB would make it even worse. The long tube between the two helps dampen out the differences.

I may be talking out of my *** on this one ... but it's something to think about.

pengaru

jt might actually be the opposite, the tube in stock form is a rubbery plastic, it's not quite solid. The longer it is the more the 'damer', so when the throttle opens and suction is increased, it's possible the walls of the stock tube 'give' a little bit before the AFM sees more flow, it's minor but that would actually be increasing the lag of the AFM.





Making the tube shorter would reduce that, making it more ridgid would also have the same effect. However, I'm not sure about any turbulence the AFM introduces which the long path between it and the throttle body may help smooth out.

Apex13B

i was always wondering if you could put a SVT mustang afm (hot wire) in there and wire it up to fool the ecu

pengaru

wiring a hotwire would be nice since it's less restrictive, however I don't think the signals are anything close to resembling one another.





the signal off the AFM on the FC is wacky, it cycles between the range as the flapper moves. If you take the cover off the AFM you can see a bunch of black solid arrowheads overlapping one another, every arrowhead is basically the full range of the flapper's resistance.



so it's not a linear pot, it's like a segmented pot and the ECU must count how many segments it's gone past to figure out what one it's in right now. I don't think hotwire MAF's are like this at all, it looks like mazda used this so they could still have a large range, without losing resolution, without increasing the resistance range.



so if you hook a multimeter up to the AFM's pot, you get something like





ohms: 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10



% open: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30



the numbers are not accurate to what the AFM does as far as ohms, but the behaviour is shown... you can observe it easily on your own car, it's quite strange.

RX7 13B 4 UR AZZ

???? OMG ????? why do they make damn cars with so much complicate ****. Right there the AFM is not only restrictive but it is not efficient in its design. So in other words the only way to completly get rid of it is to go standalone?? Damn. well guess its gonna stay there for a while LOL. What would you guys reccomend of a N2O shot on a stock 88 N/A? Im going to put RB headers, RB pre-silencer, & Apex i dual exhaust, Some form of cold air and running premium fuel(Which I do every day)? I am also an automatic do you guys have any techniques runing N2O on an auto?

1Revvin7

Well 1st off high octane will make n/a motors loose hp, it burns slower, you should only use higher ocatane on n/a motors if you experience knocking or pingin, then it will help elimate those. Yea n20 would be your best bet for some power, just keep it a simple 50-75shot.