Rx-7 Vaf

[92MazdaJ]

ive been reading the forum and i see peoplemention the rx-7 vaf?? what exactly is this, what does it do, and does it help a sohc 1.8 performance??

thanks

[Tazman2]

Nope. Mainly for us BP guys because above 6k or so our stock VAF kind of chokes the motor slightly and the RX7 one helps then!

[OUfb2005]

are these rx7 vaf's plug n play?

[jamaican]

are these rx7 vaf's plug n play?

In most cases, the RX7 VAF will need to be tuned to the ECU of the Protege/EGT. In order to tune it you will need the following: Multimeter, sharpie or similar permanent marker, tape, small pick tools or small screwdrivers, utility knife, silicone sealant, battery connector removal tools, general mechanics tools and some patience.

The RX7 VAF needed is an 86-88 non-turbo "B" code VAF

Look for this sticker on the VAF, the numbers will be identical.

The RX7 VAF referred to on this page is from a 87 non-turbo 13B

Removal of OEM VAF

1. Depending on your present set-up, removal of the VAF is quite simple. Disconnect all intake clamps and hoses, including the filter or filter box, the VAF unplugs from the harness, (see photo) NOT BY UNSCREWING IT!!!! but buy carefully prying back the spring clips on either side and sliding it off. The OEM plug still in the car, will plug in directly to the RX7 VAF.

2. You'll notice with a side by side comparison that the RX7 VAF is larger and the outlet diameter to the H-Box is larger. 3" hose adapters do fine, as a 2.5" did it on the OEM VAF. I suggest using a nice 2.5" to 3" hose adapter for connection to the H-Box, makes a much better seal than a 3" to 3". The same air filter adapter from HKS fit fine on the RX7 VAF inlet. But you'll also notice that the OEM VAF used studs and nuts, the RX7 VAF uses threaded holes and bolts. So when you go and get your RX7 VAF, MAKE SURE TO GET THE BOLTS FOR THE ADAPTER!!!! I got lucky and found an 87 RX7 engine still fully intact, just the interior was gutted, I grabbed as many OEM bolts as I could, makes for easier mounting of brackets or whatnot to be able to use a factory threaded locations...

3. Make sure to save all OEM parts that go with the OEM VAF, including the VAF itself, as you may need to re-install it all if the RX7 VAF is defective or some other component is defective and the car won't run correctly with the RX7 VAF.

Tuning the RX7 VAF

1. Make sure your intake system is completely intact before you go ahead with this tuning process.

1a. Remove negative battery cable from battery. This resets, the factory ECU to reboot with the new air flow specs. Let car sit with cable removed for about 5 mins. This can be done while you cut the cover off the VAF so save time. Or even cut the top off before installing and disconnect battery while removing the old VAF would save even more time.

1b. Remove the black plastic cover from the VAF by cutting the silicone with the utility knife, be careful not to cut too deep as the black cover has an edge on it that needs to be there.

1c. Reconnect and start engine, the engine may stumble at first, but it will smooth out somewhat to allow for adjustment. So have your meter and tools set up to act rather briskly.

2. With engine running, take your Multimeter Red probe, and probe the O2 sensor wire coming from the single wire O2 sensor on the exhaust manifold, (see photo) The wire runs up along the block to under the distributor to a gray plug, you can probe the wire anywhere along it's path, or just probe the wire inside the plug. Put the Black probe to chassis ground. As I understood, you are looking for 0.45volts at idle. I found mine best suited dancing around 0.53v and 0.78v, so I left it as is. Which in turn was 5 clicks.

3. The clicks mentioned above are in relation to the now opened VAF. (see photo) You will see a large wheel spring with teeth on it. You will also see a small black spring that grabs at the teeth to hold it in place. With your marker, mark the wheel where the springs sits on the wheel BEFORE YOU TOUCH IT. With your pick tools or small screwdrivers, carefully pry the spring back and move the wheel towards the fender, (CCW counter clockwise) It may take more or less "clicks" for your particular application, but generally it's around 5 or 6. It may even need to be turned CW clockwise, it all depends on the application, year and model the VAF came from, condition of the VAF and the ECU/vehicle its being mated with. Once you have it tuned to a nice smooth idle, your meter should read within 0.45v and 0.78v for the Protege/EGT BP 1.8L DOHC. Again, readings may vary. Consult your repair manual for factory specs.

3a. You will notice the engine smooth out as you turn the wheel on the VAF. Once you have a nice smooth idle and your meter is within the specs, your all set. Cover the VAF with the Black cover with some tape temporarily and go road test it. Make sure the car warms up. You will notice a nice boost of 5hp around 6000rpm. This swap is really only to improve on the top end at 6000rpm and above, otherwise the RX7 VAF works just like the OEM VAF, there's no difference until 6000+rpm.

[92MazdaJ]

thanks!

[jamaican]

i'm not sure if it works on a sohc though

[92MazdaJ]

yeah I know but thanks for taking the time to post all the informantion for me,

[jamaican]

anyone ever tune their RX7 VAF that way?? first i thought that was the correct way above then i did lots of searching and saw people criticizing it because it's not manufacturer specs

now i'm confused... i know at least 50 people on here have a VAF, what method did you tune yours?

what about this way? should i get a cheap A/F gauge?

Well this project is officially complete.

My dad tuned it the right way. First off, my dad found my freon leak...that's another story though...

2nd, he pointed out that plug on the VAF...that changes how rich/lean it runs in a different way, but messing with it didn't help it much so it was left as is. Next, we found that when my brother screwed with the meter the first time I put it on the car, he moved the black piece by lostening the hex bolt and turning the assembly bit. This in turn made it so that the fuel pump cut off was not touching. So my dad adjusted that so it touched. Then, using the shop manuel for the voltage of the 2nd terminal in the VAF, he tuned it to match both with the key in the ON position car off and with it running, to the best he could. Ofcourse then changed the idle speed...the throttle response is instant and the car pulls freggin hard especially at high RPM...I did a 3 second 2nd gear scratch on a level surface with both wheels, and I nearly get wheel spin in 1st on avarage pavement, ofcourse that's with my 205/45/16 Proxes FZ4s...I'd prolly get a lot of burnage on my regular 14"s...

So I decided to use MazdaRacer's VAF pic and add arrows to tell you how my dad, a Mazda Master Tech, tuned the VAF properly:

The GREEN arrow is the active voltage to the meter which changes when you move the black center piece. With a voltmeter(black probe on ground, red on that terminal that the green arrow points to), you should attempt to achieve these actual Mazda specs as seen in the Protege shop manual:
3.3 volts with the car running.
3.8 volts with the key in the ON position



You won't be able to get the exact numbers but get as close as possible, then tighten down the hex bolt. You can turn the tightened black piece with the car running, counter clock wise(CCW) is rich, clock wise(CW) is lean, and you can see how it affects the engine.
The best way to tune this is with the engine off key in the ON position. Losten the hex bolt and turn the black piece and watch your volt meter and get it to 3.8V, or as close to it as possible, and tighten the hex bolt. Turn the car on and you should get somewhere near 3.3V. With the engine off the fuel pump cut off contact needs to be touching.

Hope this helps any, and makes any sense...I've been leaning under the hood of my running Protege(with exposed exhaust manifold) in the shop which is hot because it got up to 94*F today, so I'm pretty exhausted.
But atleast my car runs GOOD!

[Tazman2]

If you have a multimeter you can also use that instead of having to buy a a/f meter for a quick tune!

[jamaican]

If you have a multimeter you can also use that instead of having to buy a a/f meter for a quick tune!

yea i know about the multimeter method... it has to be between 0.45v and 0.78v

but some people said they have trouble doing it that way and they get readings all over the place

i just wanted to do it properly

[MazKid]

That's actually my old method...now(well, on my current AFM, which is a K-code with the U-code circuit board) I just tune the tension, drive the car, and go from there...if it drives better, good, if not, then I retune it. My car's running great now though.

[Tazman2]

yea i know about the multimeter method... it has to be between 0.45v and 0.78v

but some people said they have trouble doing it that way and they get readings all over the place

i just wanted to do it properly

I dunno about you but i trust a multimeter over a cheap pos A/F meter that just "lights up"! But yeah it will seem like its all over the place because it changes so quickly so instead of your brain seeing lights going back and forth, etc. it just sees that number going nuts.

PS: Actually i wonder if i still have my homemade A/F meter laying around somewheres from back in the day when i had a Conquest!

[jamaican]

can i use any multimeter? is there a special kind to measure .55v?

[Tazman2]

can i use any multimeter? is there a special kind to measure .55v?

You just need to set it to probably the lowest setting so it shows upto 1.00 volts but i don't have one handy atm as i haven't used one in years!

[jamaican]

That's actually my old method...now(well, on my current AFM, which is a K-code with the U-code circuit board) I just tune the tension, drive the car, and go from there...if it drives better, good, if not, then I retune it. My car's running great now though.

is the k code with u code circuit board better? howcome?