[cn07ob]

07sti ,cobb catted tbe ,k/n typhoon cai ,v104stg2 91 oct map,walbro f/pump. Never a cel, fuel cut, backfire,etc. Imho this intake is same diameter as stock, with less bends in the area of the MAF compared to stock.Cobbs maps(ots) are very rich, just look at my exhaust tip. I"ll take my chances.I"ll keep you posted.

[WRX4ME LE 482]

Originally Posted by stretch

When I had an AEM intake on my 2005 (it was installed when I bought it), there was a CEL for running lean. The fuel trims weren't far off at idle, but since the MAF was after a bend in the piping, the fuel trims would fluctuate. The problem isn't specific to AEM- this will happen in ANY CAI since they ALL put the MAF after the bend, thus none of them are safe to run without calibration. Even with calibration, your a/f ratio is going to fluctuate due to the varying turbulence of the intake air around the MAF sensor, so one should add a little bit more safety in the tune (tune a little richer than normal).

The power boost could be felt since the car was untuned and thus would have otherwise been running too rich, but I removed it prior to flashing to Stage 2 for safety.

See, this is news to me. Ive heard nothing but good things about the AEM/Prodrive unit with regards to its operation with the maf. In fact, most articles/reviews/people say it doesnt change a thing.

[subaru_sti293]

I'm in stage 2 with APS 65mm , even i changed my injector to DW 650cc still too lean my Tuner can't figure out though. Is that possible if i change to 750cc injector it would help to solve the problem?

[Spoolin415]

Originally Posted by subaru_sti293

I'm in stage 2 with APS 65mm , even i changed my injector to DW 650cc still too lean my Tuner can't figure out though. Is that possible if i change to 750cc injector it would help to solve the problem?

Might want to get a new tuner or troubleshoot because something isn't right. Stock fuel pump? I'm catless Stage 2 w/APS 65mm on stock injectors and I'm not seeing 100% IDC.

[stretch]

Originally Posted by WRX4ME LE 482

See, this is news to me. Ive heard nothing but good things about the AEM/Prodrive unit with regards to its operation with the maf. In fact, most articles/reviews/people say it doesnt change a thing.

Well, think of it this way. The factory intake draws in cold air already, so there's no power to be made there. (The numbers can be fudged a bit by letting the car idle in heat, but really the stock intake is already good here.)

So, where's the power being made?

One might think power is being made from a lower pressure loss in the intake (ie, higher flow capability). This is possible. But where is the largest pressure drop in an intake? It happens right at the MAF, since that is where the tubing is narrow and the large, obtrusive sensor sits right in the center of the air flow. For an intake to not throw off the stock calibration (by maintaining the stcok diameter), it also cannot alleviate the primary pressure drop of the stock intake.

The other piping in the intake can make some difference in flow, but usually it won't amount to as much. This is why large MAF diameter intakes are beneficial, but also why they require the MAF sensor to be recalibrated. And as I said earlier, if the MAF is after a bend, you can't really calibrate the MAF accurately, which is why the stock MAF location carefully puts the MAF directly after the air box with a velocity stack.

In the STI, this creates the problem of how to create an intake that draws in cold air, increases the diameter around the MAF, AND doesn't put the MAF after a bend. A good intake will do all three. A shorty intake might keep the MAF accurate but draw in warm air. A cold air intake might draw in cool air but throw off the MAF. The best solution would be a stock-like airbox but designed for higher flow (or a shorty intake with both a good heat shield and a forced cold air source, which is basically the same thing). Extending the wiring to the MAF to mount it near the filter in a cold air intake could also work, but care must be taken so that the MAF does not register gusts of wind blowing into the pipe.

Like I said, my AEM intake kept the fuel trims correct at idle. That's easy for them to do, but to keep the MAF accurate through its entire range gets tricky. It matched the stock MAF diameter exactly, but still made power due to a leaning of the air/fuel ratio mostly (but not entirely) above the open-loop range where the car monitors the air/fuel ratio. This isn't the right way to do things.

[cobb_sti]

Originally Posted by Hirogen

This wasn't designed to be a short ram bashing post guys, everyone can have their own reasons for everything. All I was trying to do was share the tests I've conducted and the hard data from a professional. When Chris was going over the chart with me he basically said look what your cold air intake did to the AFR, you were running 13:1 at one point.

** Here's the actual images of my dyno chart. Critique it a bit, let me know what you guys think. Cobb Catted tbe, APS 65mm and walbro

You keep saying you saying you were running 13:1 "at one point" meaning at only one instance were you 13:1. well you can't always just run 10:1, it have to come down from somewhere. So if it passes by 13:1 on it's way to 10:1, does that mean you were "running 13:1 at one point"?

[cobb_sti]

^^^ sorry i'm just being difficult.

Hardware Requirements

: Otherwise stock vehicle with a STOCK INTAKE

SYSTEM ONLY, tested with a Cobb Tuning turbo-back exhaust system
with high-flow catalytic converter. An equivalent turbo-back exhaust
system could be used. If the turbo-back exhaust system relieves
back-pressure to an excessive point boost creep is possible. If a
lesser flowing turbo-back exhaust system is used then boost targets
may not be achievable. The addition of any other hardware may make
the vehicle perform poorly.

[cobb_sti]

So are you saying that even stage 1 isn't safe without a protune?

[Hirogen]

Well... just to clarify that Im not a dumb a s s here... we all know the map is supposed to be used with a stock box and thats what I did. I simply was doing testing to see how compatible the 65mm intake was with the cobb map.. since it was the same diameter is was SUPPOSED to not cause many problems.

**Look at the air fuels man this isn't rocket science but I'll explain it anyway I didnt even hit 12:1 until 5k. If you think I'm wrong that the AFR was fine then please call one of the best tuners in the country and tell him that he's wrong. I'd rather not fill my thread with smartass posts when I'm just trying to help others from popping motors and a huge headache. The bottom line is that intake leaned the crap out of my car and I wanted to let others know because I KNOW There are others out there running intakes on their cobb mapped cars.

This had nothing to do with stage 1.. read the original experiment again it was all stage 2 V1.04

[cobb_sti]

no man i was just going off on a tangent and asking how safe stage 1 is. Yes i realize it's a smartass remark, that's obvious. I didn't mean anything personally to you by it. I agree with most of what your saying. I was mostly just playing devils advocate. On a side note though, how do you know chris is one of the best tuners in the country?

[Hirogen]

XX Tuning

I'm sure a few others will feel free to chime in for him