Intakes suck

[DropTopZeek]

The time has come for the dreaded smog check... time to swap my stock air box back on. To my dismay I couldn’t find any of the hardware so I mixed and matched miscellaneous screws. Anyways, I instantly noticed that the car ran smoother with the stock box back on (all I did was spray it out with an air gun and clean out that little side box full of muffling garbage). Surely, I’m mistaken, and my cone intake was better. Or maybe not. I DID only have 3 of 4 bolts in the adaptor for the filter to link to the afm, so maybe a slight leak or something misdirected the air and effected the idle? Fun little mystery.

[twotone_ra64]

Ugh, smog checks... My Celica is due for smog this year and my appointment is this Saturday morning. As far as intakes, sometimes stock is just better. This is the case with my Miata, but removing the stock system proved to function worse because Mazda did all this intake tube chamber stuff with the airbox and the intake tube to smooth out the powerband at certain rpm... maybe it's the same case with the Celica to some degree?

[ozzie]

"Cold" Cone-style air intakes usually draw warm air from under the hood, unless they're piped to somewhere outside the engine bay. Warm air is good for efficiency, bad for power. The stock intake on most cars has some sort of pipe feeding it outside air.

[Teranfirbt]

depending on the quality of the cone and adapter, you may have had slight losses on the inlet to the AFM. If you look, there's a small velocity stack style transition between the air filter area and the AFM on the factory air box.
Realistically, it probably changed nothing. Cone air filters don't really do anything, they're better at letter more dirt in than air (unless the factory air filter was seriously undersized).
Engine masters did an episode where they tested 19 different air filters and found that the *best* combo was the K&N filter top attached to a big ass salad bowl! That's right, just the top, not the whole K&N filter.

[swan song]

I watched that episode last night! The salad bowl cracked me up. I’m imagining, with how influential those guys are, that we will see a trend in salad bowl carb toppers.

[twotone_ra64]

depending on the quality of the cone and adapter, you may have had slight losses on the inlet to the AFM. If you look, there's a small velocity stack style transition between the air filter area and the AFM on the factory air box.
Realistically, it probably changed nothing. Cone air filters don't really do anything, they're better at letter more dirt in than air (unless the factory air filter was seriously undersized).

Well, there you have it. And that makes sense to me. Nothing wrong with my stock airbox and cylindrical filter, either.

[TerrenceLP]

We don't need no AFM!

But i concur - NA engines are finicky when it comes to intake track and pulses etc...

[RedCar]

Whoa! How did you do that!?
Did you have to short the afm plug with resistors to fool computer that afm is still there?

[ozzie]

Or are you using Megasquirt or some other engine management with a MAP sensor?

[ozzie]

I watched that episode last night! The salad bowl cracked me up. I’m imagining, with how influential those guys are, that we will see a trend in salad bowl carb toppers.

It kinda makes sense, it's going to be easier to pull air straight down through the top then to pull it through the sides, and the salad bowl has a large volume of filtered air, and should pull air through the entire filter, where a shorter filter would just pull it through the center of it. The one I don't get is the one they duct taped, maybe by forcing a greater volume of air through the top filtration material, it expanded the pores to allow air to flow through more easily?

[swan song]

Speaking of air intakes. I bought my eGay 1uzfe cold air intake. Should be full of fail.

[DropTopZeek]

Nahhhhh I’m sure it’ll be great. Sometimes Ebay is the best. Sometimes it’s pure garbage...

[ozzie]

Nahhhhh I’m sure it’ll be great. Sometimes Ebay is the best. Usually it’s pure garbage...

Fixed

[Teranfirbt]

Whoa! How did you do that!?
Did you have to short the afm plug with resistors to fool computer that afm is still there?

I'm sure Ozzie hit it right on. The factory ECU won't work without the AFM present, and you can't trick the ECU into thinking the AFM is there with resistors. The AFM is a variable resistor (potentiometer) attached to a mechanical flapper that moves with airflow. If you put in fixed resistors the only time it would run right is when the resistors matched the equivalent airflow going into the engine (not very often!)

[RedCar]

You guys are totally right!.. I should have checked Terrance's earlier posts: http://www.celica-gts.com/forums/index.php?topic=30340.msg434314#msg434314

I am somewhat intrigued by the idea of replacing AFM with resistors: Having checked the resistance of the potentiometer (E2-Vs) on a couple AFMs (both probably worn out), I was surprised at how random the values were. The FSM says it's suposed to be between 20-1000 ohms at intermediate flow positions, and they were but the value just jumps up and down randomly with increased flow opening. Despite all this, the engine works just fine... my AFR gauge indicates nearly perfect mixture control.

I speculate that the AFM is more of a backup in the event that O2 sensor fails, and is mostly useful on initial starting while o2 sensor is warming up... and wonder how well a resistor (sized for startup condition) would do in it's place (given a properly functioning o2 sensor)... I'll let you guys know if I end up trying this!