hi, i just installed the rx7 afm on my miata. I researched and it said that it was suppose to bolt on and work fine. Also i have the greddy turbo kit. When my car is idling it seems to stumble and the rpm needle drops to about 500rpm. Is that normal? in addition, their seems to be a pinging noise coming from my engine and its pretty loud. newbie needs you help

 

If you installed the RX-7 AFM without making any adjustments in conjunction with your stock injectors, then you're running lean (hence the pinging). With stock injectors, you'll likely have to loosen the flapper door spring 6-8 clicks, which can cause other drivability problems (such as sub-par performance in closed-loop, stumbling idle, etc.).

If you were to pair the AFM with the 1.8L injectors (or something even bigger), you wouldn't have to loosen the flapper door as much (or even tighten it, depending on how big the injectors are), so it would run much better. There is some good, albeit old, information here: http://members.aol.com/solomiata/airflowmtr.html

 

yep the opening is so much larger that you have to reclibrate the clock spring like the site Brian mentioned says.. Why ad th eafm if you dont want bigger injectors sure it will flow abit more but under boost the turbo is sucking pretty hard anyway. If you get some 310's-330's then you will need to tighten the spring at least 3 clicks probably more.
Most people with stock injectors run about 8 clicks loose. your results will vary of course just be patient.

 

thanks a lot for your reply. I'll give that a try and wait till my 1.8l injectors get here.

 

sorry im a little confused about what the springy thing u guys r telling me to loosen looks like. is it the circular wheel thing

 

you see the wheel with the little clip in it? that's what your turn. Mark your starting position so you will always know where to fall back on. I ran one with my 1.6 injectors at 6 clicks. any tighter and the rpms would bounce when I came to stops.

The bigger the injectors the more youll want to loosen it back to lean out the system a bit.

 

now im a little confused bripab007 said to loosen the spring(now i know which one ) but braineack says to tighten it. heres my set just incase it makes a difference:

1992 1.6l
Greddy turbo kit
bipes acu
custom 2.5 exhaust
rx7 afm
stock injectors

 

Sorry I'm backwards.

 

i still have a semi-polished rx-7 VAF for sale, tuned for a miata.

 

thanks again, but as i did more researched online and found on a website that it said to reset your ecu by disconnecting your battery so that the ecu can take into account the higher air flow. So i tried it because i was affraid to open the afm and so far it seemed to work. no pinging and no rough idle.

 

opening the AFm is no big deal it just involves taking of the plastic cover and then moving the spring holder position a certian number of clicks but so long as you have it working good for you. If you ever want to use it to go bigger the info on that is the same good luck.

 

after adjusting the clockspring under the cover, you can/should remove the slug on the top. there is an adjustment screw on there that can help you fine tune it.

 

here's a pic of the fine adjustment i'm talking about:

 

arrows point to the "teeth" on the clock spring. mark the original position with a sharpie.

 

well i thought i was done with this after reseting the ecu but a lil later it started to ping and the rough idle began. thanks for the pics kung fu jesus they helped clear a lot of confusion. so tomorrow ima take it apart and see what happens.