2005 wrx sti no tune

Ok so I have an 05 sti all stock 1900 miles on rebuilt motor and just a 70mm aps cold air intake with no tune. I just ordered a catback exhaust system and I plan to bolt it on one of these days.Once I put it on would it require to have a tune? I dont have a tune for my intake and soon to be exhaust system. Will the car run fine?

You shouldve gotten a tune after installing the intake. The only intake that doesnt require a tune, although is recommended, is the cobb sf intake.

Catback doesnt require a tune but a turboback does.

Others that are more knowledgeable will chime in as well.

Thanks man! Yours is the most knowledgeable so far since noone else wants to help!!

Alinro hit it right on the head.

yep, i'd get a tune with the intake.Do you have a tactrix or AP?

Grinder34 said:

yep, i'd get a tune with the intake.Do you have a tactrix or AP?

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Its a 70mm aps cai

SeanZ said:

Its a 70mm aps cai

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Oh man. Def want a tune on that.

Refrain from WOT and anything with heavy load. (I would say limit it to no more than 50% throttle)

The stock intake on the 05 is 66mm. If you had an intake that was the same size you could probably get away with out a tune, but yours is bigger @ 70mm and now the measured mass of air is lower than what is actually passing so the ECU will not be supplying enough fuel and you will be running lean through out any open loop driving (WOT, heavy load, high RPM).

You should get yourself a tune ASAP because your car is now a ticking time bomb. Do you have an AccessPort or a Tactrix? If you looked at your fuel trims you will see that it is adding about 6% or so more fuel than normal.

My bad its a 65mm aps cold air intake!

Does it still need tune with 65mm intake???

I would just throw the stock intake back on till you get a turbo back, Walbro pump, and then do a tune.

SeanZ said:

Does it still need tune with 65mm intake???

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The 65 is better with out a tune because you will now be slightly on the rich side. I believe this is why they make it slightly smaller than stock to maintain a level of safety. To me that makes for a bad intake in any case because what is the point of replacing your intake in the first place... it is to improve flow and volume. With a smaller intake it is near impossible to achieve that when nothing else has changed. Regardless I would still have it tuned to get the most out of it but if you don't there would be little harm.

In all honesty that intake is doing nothing for you right now and tuned it will do less than the stock unit. When everything else is stock (Excluding exhaust) the absolute best intake is the stock intake with a K&N Filter. :tup: The stock unit is very much like a cold air intake anyway because it is drawing air from outside the engine compartment.

see Holy's post above. Its a good idea to get tuned, or at LEAST do some logs to make sure you're ok.

Do you already have engine management tools (accessport, tactrix)?

Grinder34 said:

see Holy's post above. Its a good idea to get tuned, or at LEAST do some logs to make sure you're ok.

Do you already have engine management tools (accessport, tactrix)?

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Nothing! stock ecu

well you'll need to get something eventually. I think theres a guide to choosing somewhere, but it boils down to this:

Accessport:
Ease of use
Small self-contained module so you dont need a laptop for most things
Module can display engine parameters for you real-time (eg, it can be used as a boost gauge)
A few popular off-the-shelf maps

Tactrix:
Cheaper
Requires laptop
Off-the-shelf tunes are all user created
A few extra tuning options for hard-core tuners

Might as well pick one now and start logging and make sure your engine is running safely.