is this a good buy for a 02' wrx?

[MikeSTI]

just be carefull that your not looking at an RS

[bmxstreetrider666]

i almost dont know where to begin there is so many great deals on autotrader and there all within a good distance

[bmxstreetrider666]

the guy from norms auto is trying to make me all sorts of deals i still think a private seller is the way to go

[Dean]

cars.com is the other good source. It is where most of the Newspaper classifieds end up. make sure you check out the value on KBB.com

You always want to start at or below the "trade-In" value. when negotiating. This is what is referred to as "wholesale" Kelly blue book. The private party and retail values are worth having as well.

If I'm serious, I will do those for each of the conditions, fair, good, excelent to know where I am barganing from, and to show if I am in a negotiation.

[ScottyS]

Originally Posted by Dean

cars.com is the other good source. It is where most of the Newspaper classifieds end up. make sure you check out the value on KBB.com

You always want to start at or below the "trade-In" value. when negotiating. This is what is referred to as "wholesale" Kelly blue book. The private party and retail values are worth having as well.

If I'm serious, I will do those for each of the conditions, fair, good, excelent to know where I am barganing from, and to show if I am in a negotiation.

I found the green wagon on Cars.com --- it had been listed in the Sac newspaper. Great source.

[Kevin M]

Originally Posted by bmxstreetrider666

the guy from norms auto is trying to make me all sorts of deals i still think a private seller is the way to go

Dealers have a lot more restrictions and liabilities when they sell cars than a private seller does. I would always prefer a dealer to a private seller if I could get a decent price.

[Kevin M]

Originally Posted by AtomicLabMonkey

Is it a problem with the stock MAF transfer function, like it just doesn't go up high enough for the ECU to interpolate accurately once you've changed the intake tubing? Or does the Subaru MAF hardware just give an inaccurate signal past the factory specified range? Either way, that's just strange to me. You can pretty much change the entire exhaust, intake piping, manifolds, etc. on a Mustang and the computer will compensate for it with the stock meter, as long as the injectors aren't maxed out. Just replacing the intake piping in front of the meter is a very small change to whack out the computer that bad...

CAIs basically cause the MAF not to correctly read the amount of air flowing into the engine. most of them will flow more than what the MAF sees, so the car gets leaned out. The WRX will add fuel long term, but when you first get lean, it causes minor detonation which causes the ecu to learn to pull timing, and MBT is more important to making power in an EJ20 than the exact A/F ratio. In closed loop fueling, using the O2 sensor feedback, the ECU does adjust fuel and nothing bad happens. but under WOT/high RPMs when it switched to open loop and goes by the maps in the memory, it's suddenly lean and starts knocking. In open loop, there's not much authority over long term fuel trim, and pulling timing is the first defense against detonation.

[AtomicLabMonkey]

Originally Posted by BAN SUVS

CAIs basically cause the MAF not to correctly read the amount of air flowing into the engine. most of them will flow more than what the MAF sees, so the car gets leaned out. The WRX will add fuel long term, but when you first get lean, it causes minor detonation which causes the ecu to learn to pull timing, and MBT is more important to making power in an EJ20 than the exact A/F ratio. In closed loop fueling, using the O2 sensor feedback, the ECU does adjust fuel and nothing bad happens. but under WOT/high RPMs when it switched to open loop and goes by the maps in the memory, it's suddenly lean and starts knocking. In open loop, there's not much authority over long term fuel trim, and pulling timing is the first defense against detonation.

So, two questions:

1) How can the MAF not correctly read the amount of air flowing through the intake tubing? It's a closed system, so any "extra" air that the engine sucks in as a result of less inlet restriction has to pass through the meter. Is it an issue with the physical meter placement, right after a tubing bend in the CAI or something? I could understand that, it's sometimes an issue on mustangs since the meter is placed right next to the air filter, and consequently any aftermarket CAI piping bend that comes in from under the fender... if the meter is clocked so that the wire elements inside are on the inside of the bend, they have trouble reading accurately.

2) You touched on this, but it seems wierd to me; do your cars not apply open loop/long term fuel trim corrections based on what it learns during closed loop? That's what the strategy I'm used to working with does...

[Kevin M]

1) Different tube diameters, basically. Even a millimeter difference is sufficient for screwball reading. Plus, the relationship between air flow and MAF sensor voltage is non linear, so it's also not a simple across the board correction to fix it. I've done some serious soapboxing on this subject on i-club, I'll go find it in a few minutes.

2) It does, but not to the same extent. Another limitation is that the stock ECU can't monitor knock at about 5500-6500 rpm, because at those RPMs normal engine noise is the same frequency as detonation, so the sensor is disabled. That's where CAIs, if they're particularly poorly designed, can cause damage directly.

[Kevin M]

http://www.i-club.com/forums/showthread.php?t=36823

longish, but it's all either a tech-biased post or some stupid ricer saying "my CAI rulZors!" or something, so it doesn't actually waste much time to read the whole thing.

[AtomicLabMonkey]

Originally Posted by BAN SUVS

Another limitation is that the stock ECU can't monitor knock at about 5500-6500 rpm, because at those RPMs normal engine noise is the same frequency as detonation, so the sensor is disabled. That's where CAIs, if they're particularly poorly designed, can cause damage directly.

Ah ha. That would be bad.

Originally Posted by BAN SUVS

1) Different tube diameters, basically. Even a millimeter difference is sufficient for screwball reading. Plus, the relationship between air flow and MAF sensor voltage is non linear, so it's also not a simple across the board correction to fix it. I've done some serious soapboxing on this subject on i-club, I'll go find it in a few minutes.

Okay, on my car the MAF is a distinct tube section of its own, that looks something like this:

Even if you change something else in the intake tract, all that extra air still has to flow through the same diameter tube that the meter and computer are calibrated for, and will consequently be going the right speed to give an accurate reading.

Is it a different arrangement on your cars? Does installing a CAI mean people are pulling the sensor hardware out of the factory tube and plugging it into a bigger one or something?

[Kevin M]

Yeah, on a WRX the MAF is actually bolted to the back of the air filter box. When you put in a CAI, you unbolt it and put it into the tube, which in theory is supposed to match the diameter of the stock tube in the airbox, but...

Also, some CAIs are intentionally larger to allow the MAF to read more air than the stock size can read, but it requires EM, and still can nevcer be fully calibrated perfectly.

[AtomicLabMonkey]

Okay, THAT was the piece of info I was missing.

[Kevin M]

Originally Posted by AtomicLabMonkey

Okay, THAT was the piece of info I was missing.

Silly Mustang driver. Yeah, WRXs have a lot of quirks with tuning that you need to know about. It's amazing how many new owners show up on our board after owning a DSM or turbo Honda or whatever and can't get it out of their heads that Subarus really are that different. You should read that thread I linked- it'll help you to fell my pain as a moderator.

[bmxstreetrider666]

well there is still 16 hours left on the auction and the buy it price is at $10,800 so i will have to probabally keep looking if i want to get a clean title. the downside is that i will easily be spending another 5$k. oh well you get what you pay for.