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Can't go fast! Need help

2K views 12 replies 4 participants last post by  AllExtinct 
#1 ·
So i recently changed my oil. Normally i use conventional oil 5w-30, as the 2004 WRX calls for. However, i got synthetic because, well i'm lazy and every 6,000 miles sounds better than 3,000. Soon after i changed the oil i've notced that if I try to accelerate past 3,000 RPM's the engine seems like it's choking itself, almost as if it's cutting off it's own airflow. I'm not sure if i put too much oil in and the pump is just sucking foam( it takes 4.8 qts and i put a little less than 5) or if it's the synthetic (i know it has a little different viscosity than conventional) but i'm really concerned i might be damaging the engine, please give some advice
 
#2 ·
you have a high performance turbocharged vehicle. being lazy is not an option. if needs alot of maintenance like the high school prom queen.

i use motul synthetic and i change my oil every 4000KM (2500mi) and change my air filter every 2 oil changes. i also do my fuel filter, pcv valve, and a few other things once a year whether it needs it or not. being cheap and lazy will only cause the pre-mature death of your wrx.

as for your issue, it sounds like a boost/vacuum leak. do a leak down test and see what your results are.

cheers!
 
#3 ·
The leak down test is definitely a good call.

You may also want to check that you closed the 710 cap tightly. That can cause some minor vacuum leak as well.

And just for your own piece of mind you might want to take a sample and send it into Blackstone or a similar lab for a used oil analysis. That way you can feel good about pushing your intervals outside the manufacturers recommended length.
 
#4 ·
Found it has nothing to do with oil. The air inlet tube, just after the cold air intake air filter and hose, has some wear and holes. Also my MAF sensor is failing, causing my engine to run rich. If anyone knows where to get a new MAF sensor and/or where to get a new air inlet tube for reasonable price, it would be greatly appreciated.
 
#5 ·
Have you tried to clean the MAF sensor they sell cleaner at atuozone.
Sometimes you can lucky and save yourself $100+ bucks by trying to see if that works first.
If not then cant say ya didnt try.
As for the air inlet you could probably find a good deal on ebay for one.
But if your MAF doesnt work out after trying to clean it then your best bet for that would be the auto part store.

Good luck
 
#6 ·
I ended up buying a new MAF but the problem seems to have gotten worse. Now i can barely get up to 40 MPH. I seriously have no idea what the problem is. I checked the damage on the air inlet pipe and they aren't holes, just small indents from some metal rub. If anyone can help me diagnose this problem, i'd be in your debt for saving my ride.
 
#7 ·
you need to provide more info.

what were the results from the boost/vacuum leak test? did you even perform one? visual inspections arent always 100% accurate.
are there any engine codes? you could be in limp mode.
was it the right maf? did you install it corectly with a new o-ring?

lots of variables could be taking effect. saying your car "can barely get up to 40mph" doesnt really give us enough to go off of. there could be a dozen things wrong or one little thing wrong.
 
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#8 ·
Just for the hell of it reset your ECU and see what happens.
Remove you negative terminal from your battery and press the brake pedal a few times and replace your negative terminal.
Report back with results.
 
#9 ·
After easter-egging some problem areas and calling some people, I found that my problem is likely a boost leak. I have 0 idea of where to start looking or how to fix it if i find it. I should have known when the turbo spooled up but the engine still decelerated. anyone have a DIY link on how to test for a boost leak?
 
#10 ·
@boo-key on here sells boost leak testers for $33. it works by pressurizing the system then you spray soapy water all around and look for bubbles.

or there are smoke testers and other methods. just google "wrx boost leak test" and you'll nee a good dozen videos.
 
#11 ·
Check all your vaccum lines if they look dry rotted and cracked.
Tighten all hose clamps.
The gasket under the BPV is notorious for leaking.
Your best bet is to remove your intercooler and look from there.
Check your air inlet hose clamp going to the turbo.
Check the clamps under the intercooler.
Check the small line coming from turbo to the boost solenoid.
I know theres a small line behind the alternator as well that goes into the intake manifold that comes disconnected.
 
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