cpages2

Can someone tell me or point me in the right direction for finding out this information..


I am looking for information on all the diffrences between the 2002, 2003, 2004 and 2005 Impreza WRX.

I know about the body change between 2003 and 2004.... Im looking for any other changes... (i.e. Mechanical, physical, layout etc....)


Thank you very much.

- Mike

Tits McGee

The suspension is slightly different in the rear in the 04+s I believe, making you pretty restricted to 8" wide wheels. I think you can run 8.5"s, but you're going to rub, unless you start messing with the offset. Other than that, I'm not aware of any drivetrain changes. The interiors are also different in the 04+ models, and even different between the 04s and the 05s (04s are better IMHO).

Dunno if that helped at all, and I'm sure others will pitch in about other things if theres anything I'm forgetting.

mantra1

The ECU's are a little different as well. You can not run an EM program designed for an '04 on a '02 ECU.

mranlet

Maybe this will help:

http://www.cars101.com/subaru/impreza/wrxsti2004.html

cpages2

Thanks that link was great.

xFactor

Here are the differences between 02 and 03 that I have noticed. Some are significant, others might not be.

front brake calipers
clutch\pressure plate (02's have a chattering problem in the mornings)
03- part missing to complete factory brake ducting
03- incorporates lighted ignition key ring
03- incorporates a new sensor in the fuel tank (it eludes me right now-pressure or temp (I think temp))

I'm sure others know more. The 04's have bigger changes, most notable EM. People state that the closed loop\open loop transition time is slow for emissions purposes. Add dumb boost control, and say buh-bye!
That is all I know or have heard.

later, x

cpages2

Could you explain that a little more... I didnt really understand... Thanks


The reason im checking out this info is I am almost 100% sure this june I will be buying a WRX (have a few other cars in mind, but WRX seems to be the bes tout of them). And I like the new '04 body style and it is a bit more then say an 03 or even 02... So I wanted to see what else changes there were and even if its worth getting an '04.

- Mike

subbykid

drivetrain changed (differentials, 5spd and 6spd), weight, interior, suspension, aerodynamics, to name a few things.
the link given above is a good place to read to get the facts and info you need
http://www.cars101.com/subaru/impreza/wrxsti2004.html

Each year mistake are fixed and new ideas are brought forth. Just keep an eye out.

xFactor

Okey dokey, here goes...

First I will start with the bottom line. If you like the 04+, the first power modification you should do is a software change. Ecutek and the Cobb AP both involve modifying the base programming of the ecu by reflashing it.


Now to get geeky
You really should not add an external form of boost control to the 04+'s, at least without doing the above; but then it would be redundant.

Here is the problem explained:

Closed loop = ecu looks at sensors like throttle position sensor (tps), mass airflow sensor (maf), manifold absolute pressure (map), knock sensor, coolant temp, exhaust gas temp (egt), intake air temps (iat), knock sensor, rpm's, creates a "calculated load", blah blah blah. Most important - the o2 sensor. Then it looks up tables and maps to try to correct the air\fuel ratio, making it lambda (14.7 which is optimum for catalytic converter efficiancy, READ: lean) This action creates a fuel trim memory that is both constantly referenced, updated, and adjusted - first in the short term (st fuel trim), then when patterns are repeated, long term (lt fuel trim).

Open loop = ecu looks at important stuff like map, maf, iat, rpm's, knock (until 5-6k ish rpm's where it is disabled), but not the 02. Then it looks up some different maps, Think of a toilet flushing. This is what the ecu does in factory open loop trim. It dumps fuel trying to make it as rich as possible to keep things safe safe safe.

Ok, got that?

The 02+03's basically look at the tps for transitions. 55% tps will usually flip the ecu into open loop. The 04's look for that, but need to verify some more parameters, thus taking a longer time to make the flip over to safe afr's.

Cool?

When you add boost control, like electronic or manual (ebc, mbc); superceding the ecu, you run into the situation called part throtlle\full boost (ptfb). Just like it says, you push all that air, but only dump a little fuel because you are in closed loop. People that do this with the 02-03 modify their throttle input (driving style) to keep it in open loop whenever in boost. It gets 'er dun though! Lots of people run great numbers with a mbc. It works for them.

04's are a different story. The transition input and flip time depend on a few more parameters, and there is an intentional delay (for emission purposes of course!) before going open loop. So it isn't really difficult to go way lean; with excessivley happy timing one day- kaplow!

So, yeah, the bottom line is you should refer to the first paragraph about bottom lines with the EM on the 04; even super flowing exhausts sometimes monkey with them! Saving a little longer for smart EM will make for a happier, better running rex.

Not as well known to me- I believe suspension top hats are different so spring interchangability is questionable.

I'm running out of beer... Can't hold out any longer..........
No seriously, sorry to break it down so hard ,, good luck with your pick!

later, x

cpages2

ok ok... I think I understand...

So if I do go with a 04' I should get the ECU flashed right??? About how much does it cost and will warrenty be voided because of it...


In the long run what year WRX would you recommend getting...


- Mike