vj95

Anyone ever tried this from the Downey website?


MASS AIR SENSOR MODIFICATION*
* Tampering not legal,
should only be modified for racing use.



The following adjustment can be used to richen or lean the air/fuel mixture from the factory setting. This adjustment could be necessary when using a Big Bore Throttle Body or other EFI modifications. The mass air sensor (MAS) is found on top the air cleaner canister on 1985-95 Toyota vehicles. The sensor is an aluminum housing with black plastic lid. Cut the seal holding the black plastic lid in place. Gently pry the lid from the housing. To adjust, first mark the original location of the hold-down clamp on the gear wheel so you can return to stock setting if necessary. Loosen the clamp screw and rotate the gear wheel a few teeth as necessary. Clockwise leans the mixture, counter-clockwise richens the mixture. After adjustment, replace the top plastic lid (see Warnings below).
WARNING #1 - Use caution when cutting the top lid seal with a hobby knife so that plastic lid is not cut or damaged.
WARNING #2 - DO NOT let spring loaded gear wheel unwind, you will not be able to find stock setting/home base.
WARNING #3 - Ensure you establish a good seal when replacing top lid, moisture can destroy the sensor electronics.
WARNING #4 - DO NOT use an adhesive which creates a gas or fumes when drying, fumes will coat and destroy the sensor electronics – you’ve been warned!

norcalsvx

they have been doing this since the 80's


Start by locating the AFM, which is directly behind the air box.

Next use the razor blade to cut through the silicon around the black plastic lid on the AFM. Once the lid is open you will see the flat wound spring previously referred to.

Make sure to mark the location of the gear relative to the spring before making any changes. We used a felt tip pen to make our mark.

Next loosen the screw that is connected to the clip that holds the gear in place. It should be possible to move the gear without completely removing the retaining clip.

Turn the gear counter clockwise to loosen the spring and richen the fuel mixture. We suggest only adjusting the gear one tooth at a time until the correct mixture is achieved. Too rich of a mixture will result in poor fuel mileage, sluggishness at lower RPMs, and excessive exhaust emissions.

Tighten the screw and close the lid on the top of the AFM. Once the mixture is dialed in, it is advisable to reseal the lid of the AFM with silicon. The internal components are quite fragile and susceptible to water damage.

Pull the 15 amp fuse under the dash for the electronic fuel injection (EFI) for several minutes in order to reset the ECU.

It is now time to go test the modifications for any improvement in the fuel mixture.

vj95

Thanks for the reply and the description. Are there any real change in performance? I've found with my motorcycle some of these suggestions don't net much change if any at all. But lots of people who swear by them. So before I go messing with this I would like to hear from some people that have done it.

norcalsvx

i have some power mods (head/cam/header/intake) but i have'nt mesed with it yet to see about more power

shancerlelby

its all dependant on elevation really, mods that work awesome in socal dont work so hot up here in the mountains. It's all relative. On a side note andyone know where one can tap into the o2 wire under the dash for a narrow band a/f gauge?

norcalsvx

i drive from 2500-6000ft

CJM

I would buy a used one and cut that apart before I would modify the one you know works. Just a precaution really..

neilan

id recomend thta one buys a wideband air fuel gauge before doing nay of this. it migh tfeel like more power but theres a fine line between ok and too lean. its owrth the money and makes engine management much more simple. i had found with a good air fuel gauge you can notice just about nay problem before it will do damage.