Mark 1 AFM mod?

[mr2tim]

Some years back there was a popular modification that was being tried by us tinkering types of racers looking for that performance edge.

This modification involved popping the black flap on the AFM's top and moving the spring inside afew cogs and then reassembling/sealing the black top again.

The purpose of this mod was to facilitate a faster response of the "door" inside the AFM at a slower mass air speed passsing thru the AFM.

(Be forewarned that if you went to far, that is too many cog movements, it sent you into an "idle search" and you had to back off a cog or two.)

Has anyone been involved in this mod lately out there in ToyotaLand?

[Jackstand Queen]

I did this Mod. years ago on an N.A.

I noticed no improvement in performance.

It did cause the mixture to run too rich, and fouled spark plugs quicker, and reduced MPG.

Overall . . . this Mod is now . . . . so five minutes ago . . . because it has drawbacks, and doesn't deliver the HP.

[Papo J]

That's because you're supposed to lean out the mixture not richen it up, a leaner mixture caused by the AFM flapper will also increase the timing so be very careful with it. IMO, is not worth it.

[ToyotaTechGeek]

i've done it on my SC and on several NA cars.

[ebarcus]

link to procedure? driving home or id search more :P

[BlackWidowMR2]

I've done it. Two clicks richer almost blew my muffler to pieces.

[BlackWidowMR2]

Originally Posted by BlackWidowMR2

Attachment 15466

This is my setup so far. Simple intake setup, but it works. I came up with an idea to keep the air filter dry from rainwater, but we'll get to that later.

Attachment 15467

This is the airflow meter with the stock cover detached. I have a clear cover I made for it, because I have a clear timing cover as well. Take a razor and cut the sealant around the black cover on the afm. Pry it off with a screwdriver gently. From there you'll see something similar to the pic above. Minus the clear cover and blue sealant lol.

Attachment 15468

If you look close, on the upper left side of the large round gear, there is a post sticking to it. This acts as a detent and I used this as a reference to the stock position of the gear before messing with it.(Note the small black dot on the gear.) There are two screws holding the gear in place. Loosen but dont remove these, and you can now rotate the large gear. To richen the mixture, you're going to reduce tension on the spring inside the gear by rotating the gear counter clockwise. This allows the afm to work more freely and the air being brought through it will push the vane further, telling the ecu that it needs to add more fuel.

Rotating the gear clockwise will add tension to the spring and make the vane require more air to move it, thus leaning the air/fuel mixture. I would reccomend leaning the mix one click at a time. Take it for a test drive and keep a close eye on your spark plug conditions and signs of running too lean. I wouldnt go past 2 clicks at all, and honestly I would only go one click.

If you end up running too lean, you could overheat the engine, there will be hesitation, and the tell tale backfiring on acceleration.

There are kits for newer cars that involve a rheostat basically and it goes inline with your airflow sensor and has a knob that allows you to adjust the air/fuel mix manually. This is similar to what you're doing here.

If you or anyone else decides to attempt leaning their mixture for better fuel mileage by doing this, please be aware of the possible problems it can cause if done wrong. I havent attempted to lean it, as I mentioned before. I richened mine for a little more power, and all it took was one click. Two clicks caused plug fouling, missing, and muffler explosions lol.

The clear cover adds an interesting touch, as you can see the parts moving when the engine is running.

[ebarcus]

+1 thanks! i think i have that link saved on del.

[BlackWidowMR2]

Yeah but I think all it did was improve the throttle response slightly. No power gains. I've learned a lot since that post. These are the first cars I've ever taken an interest in, I've always been geared more towards motorcycles. But essentially the same rules apply.

[oldeskewltoy]

I'm pretty sure the AFM trick, and a few others were first outlined in Pat Bradens book....



Another "trick" was to use a variable potentiometer[sp] on the efi warm up switch. This would allow SOME fuel modification

[ebarcus]

Originally Posted by oldeskewltoy

I'm pretty sure the AFM trick, and a few others were first outlined in Pat Bradens book....

http://ecx.images-amazon.com/images/...500_AA300_.jpg

Another "trick" was to use a variable potentiometer[sp] on the efi warm up switch. This would allow SOME fuel modification

new guy with the old tricks, and basic too, modifying the electrical signal, LOVE IT

im curious to what kind of POT and where its all hooked up, time to dig
I have a similar set up for the o2 sensors when im running hydrogen added