ok i'[ve read the majority of this thread and am noticing some fundamental problems with the argument that CAI is bad - I agree that it may or may not add power depending on teh design of the intake system but I don't understand how people claim you could lose power or have detonation or run lean

* Based on an article by cobb posted in this thread 2000+ wrx's have speed density. Therefore, the change of shape associated with an aftermarket cai changing the flow of air characteristics will not effect measurements.

* If there was an MAF system and the aftermarket cai changes the characteristics of the air flow enough to throw the voltage readings off and cause the car to run lean wouldn't there be a code thrown and therefore a check engine light?

Not trying to slam on anyone - i'm new to wrx's and trying to understand the issue. Thanks

 

Nope, the ONLY Subaru motors to use speed density are the '00-'04 EJ25s. All others use a MAF.

Unfortunately no, there is no code, because the engine can't tell that the MAF is getting incorrect readings. The MAF is the only input that tells the ecu how much air is flowing.

 

I KNOW I've read about a lean code.. typically put out by the o2 sensors... you have to be pretty damn lean to detonate. If the MAF is getting incorrect readings and the ECU adds fuel based on incorrect readings leading to a lean condition the o2 sensors should report this to the ecu which in turn will attempt to richen the mixture... either way this is bad but you should still get a CEL. Right? I'm new to the wrx but not new to cars - this is typically how it works....

 

Heh heh heh, seeing as to how much these new guys like their CAI's so much, I say we let them install their CAI's. It's not our car afterall

 

that's not true at all... while I admit I like the sound of the turbo and BOV my main concern is the welfare of the car... the car I bought came with the AEM CAI on it and I'm trying to guage how important it is for me to remove it. If I don't have to spend the money to get a stock setup and spend the time replacing it then I won't do it - but if I get some technically convincing arguments that it can potentially damage the car then I will. I'm just saying so far with all the reading of this and other forums I haven't been convinced that it is in fact dangerous - all I'm convinced of is that it generally does not help performance and has the POTENTIAL for making the car run lean which I'm arguing should be obvious and should not get to the point of causing serious problems without throwing a CEL - so far nobody has convinced me otherwise and that's why I'm posting in here - not to try to justify the CAI on my car because this is definitely far lower of a priority than the welfare of my engine... hope this settles any confusion and thanks for all constructive replies.

 

Well, I used to decry CAI's until I was blue in the face because I thought they were a complete waste of money since they didn't make good, reliable power. I can however see how your situation is different since it would COST you money to get back to stock setup as opposed to spending, no, wasting money on a CAI.
Put it this way: I wouldn't want anyone to GET a CAI, but if you already have it, then it's really up to what you want to do with it. If I were in your position, I'd probably try to hack it into a short ram OR get tuned by Cobb with a correct map for a CAI. Me, I could never see myself using a CAI since it violates my #1 tenet for car modifcation: reliability in conjunction with improvement. Even if a CAI doesn't make your engine "blow up" or anything dramatic like that, it's all the small problems that it wil cause that will end up being a real hassle. And in exchange for what? Mediocre to minimal power gains. Not worth it in my opinion. Maybe you can try to swap a rice-boy for his stock intake. Hook line and sinker

 

"all the small problems" - what do you mean by that exactly?

So far I have:

PROS - looks kinda cool under the hood, lets you hear the turbo, MAYBE some small gains performance wise (a matter of debate it seems)
CONS - MAYBE causes a slight lean-condition ???

I still have to assume that the basic functionality of the wrx engine management is not all that different than most cars and that if the car is running lean enough to do any damage the cel will be triggered and otherwise if it's only running slightly lean the computer should be able to compensate by adding more fuel (I know this is not ideal). So are there other problems associated with running a cai?? I'd love to get some more info on these mysterious problems...

 

Well, for one thing you'll probably get CEL's up the yin yang and your ECU might "struggle" (for lack of a better word) to accomadate the CAI. If you don't mind getting those CAI's pulled all the time and have some funkified (again, it's the best word I can find since I'm tired right now haha) ECU tendencies, then the CAI won't bug you too much I guess. I guess a problem is that the ECU might not necessarily be able to compensate for the lean condition too well and could compromise performance and durability in the long run. Not an apocalyptic problem, but a problem that can be avoided nonetheless.

You might want to read up on some of the idiosyncrasies of WRX engine management, too. It'd be helpful for a new WRX owner. Plus I'm not exactly the best candidate to open that can o' worms haha.

BTW, not to challenge you or anything, but have you read this entire thread from start to finish yet? It should've answered your questions I would have thought...

 

Just don't get one unless you have too (for a FMIC or looks if you like em). Please end this thread!

 

I've led the proverbial horse to the proverbial water with this thread. I don't really have anything new to say here, but I'm not going to lock it.

 

If you think I haven't read through this entire thread then I think YOU need to read my posts again

My questions are valid and not necessarily answered with the amount of detail I'm looking for. I got a great deal on a car that happens to have an AEM CAI on it... the engine runs strong and I don't notice any of the tell-tale signs of a lean condition and have not gotten any CELs (yet anyways).

So far the only negatives to the CAI that I can glean from this thread is that it might rob you of some power (which I believe would be due to the lean condition - although I have seen some people say that the lean condition makes the car faster ??? wtf??? please explain because that I definitely don't understand) and possibly cause detonation which I argue would be preceded in advance by a CEL light due to an overly lean condition.

It really seems like a lot of hype to me at this point...
Thanks for the responses!

 

I have an idea. Why don't you leave the CAI on for an extended period of time and report in periodically about how your car's doing. I think that'll settle the issue nicely, no?

 

deal... so far so good - although this is my first wrx so even if it was suffering a lean condition I might not be able to tell. I'll try to take a look at the plugs this weekend!

 

Cool beans. If you want, you can maybe keep up a rapport with another WRX owner local to your area who has the same set-up as you do, sans the CAI.

 

CAI might not be that useful but, the Injen CAI is dyno tuned to 10 whp and that seems like its worth the 200 bucks