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Hi There Subie-groupies. I have 2002 WRX with mild modifications. Recently the turbo started spooling slow especially in 4th and 5th. Now under low vacuum and low boost (0-5psi) it pings real bad and stutters...in any gear.....then the check engine light flashes. I am afraid to boost it. There are NO codes in the computer. I THINK the MAF sensor is bad. With my auto-x ray plugged in while driving and this stutter occurs, the lbs. of air being counted seem low, if I let up on the gas the counts become normal and engine smooths out. I have checked for boost leaks, tested fuel pressure under load, and replaced all the spark plugs for good measure.

 

Any Ideas? I hate to spend $ 275. on a new MAF and find out thats not it.

 

Thanks, Mark

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If your check engine light flashes, it will store a code, or at least its supposed to.

 

My first impression is that you have chosen a poor engine management system, if any at all, and that your cats are clogged, might check to see if you are running at or near 14.7:1 AFR

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Any difference between cold or hot engine? I'm thinking maybe the cat is clogged or something.

 

I agree, a flashing (any) CEL should have code(s) stored.

 

Do u run an oiled filter?(K & N) They have been linked to bad MAFs - search here for MAF sensor cleaning, if done carefully it can help.

 

I dunno

 

Carl

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Thanks guys, for the replies. I will check how to clean the MAF. It has a Perrin foam cone filter and intake and maybe oil got in there. The car has full 3" exhaust with NO cats. Not my choice but this is the way I got it.

I wasn't sure if MAF failures were common on WRX's

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Thanks guys, for the replies. I will check how to clean the MAF. It has a Perrin foam cone filter and intake and maybe oil got in there. The car has full 3" exhaust with NO cats. Not my choice but this is the way I got it.

I wasn't sure if MAF failures were common on WRX's

 

At one time, there was a way to replace just the wire/film element itself withoiut buying an entire MAF. If you feel the MAF is the problem, maybe contact Jamie at www.subarugenuineparts.com and ask her about that.

 

I THINK, if you unplug the MAF, and the problem is better(because it uses a default map) it means the MAF is definitely bad. But , since you have some mods, that may not work. I wonder if an O2 sensor 'bypass' mod could be bad?

 

anyway, good luck and let us know what you find out.

 

Carl

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cone filter intake can be bad mojo on these cars....

 

they can often complicate the MAF setup

and your MAF simply goes south.....

as it's not reading right and constantly over correcting

 

 

I would guess you need a new MAF.

but you need to get that code pulled to be certain

 

symptoms of a bad MAF include

inability to boost, or get into high revs without sputtering and stalling

 

I would recommend (once you resolve this)

that you buy a new MAF and get the original intake setup on that car asap

 

or you will continually have to deal with these issues....

 

contact me if we can help you price out a new MAF

but make SURE FIRST that this is what you need.

 

Jamie Thomas

Jamie at chaplins.com

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***************************

http://www.subiegal.com

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Thanks guys, for the replies. I will check how to clean the MAF. It has a Perrin foam cone filter and intake and maybe oil got in there. The car has full 3" exhaust with NO cats. Not my choice but this is the way I got it.

I wasn't sure if MAF failures were common on WRX's

 

Sometimes Autozone will read codes at no charge.

 

fyi

 

Carl

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Why not cleaning the MAF?

It can be done by gentle spraying of the element in most cars. Don't know about WRX though.

 

If it's just oil on the element, and you chose a compatible cleaner (throttle body?) I'm sure I would try that first. But there may also be a way to measure the voltage or possibly the resistance of the MAF too and determine if it is open or shorted or something that cleaning can't affect.

 

Carl

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Hi Soobie gang.! Thanks for all your help. I finally got my car fixed and wanted to report back. I never dreamed what the fix was.

 

Recap: Car is new to me, loaded with go fast goods. Engine started to miss and buck @ low boost ,Could hear loud knocking while Check Engine light would flash but NO code. I was pretty sure the MAF was failing on my '02 WRX with mods and 52k miles.

 

A/F ratio would fall, then level out or go up.

 

Cleaned the MAF. Replaced the MAF.

 

Scratched head.

 

(for 1 week)

 

Found turbo XS piggyback computer tied into main computer

 

Unplugged piggy back. Car runs fine!

 

I assume a fuel map changed somehow..?

 

Anyways. It runs great now. Thanks, Mark

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