Needs repair or Tune?
Thread Starter
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Joined: Mar 2006
Posts: 44
From: San Francisco
Car Info: 02 WRX wagen
Needs repair or Tune?
hi guys, i need some help from you guys, i bought a 02 wrx wagon not long ago, getting some problem now, i have a ramdom misfire every 2 month or 1 month, and when i bought this car, it come with a K&N Cold air intake, HKS bov, and stock exhaust, but with a Prodrive axle back. other then that, everything is stock, i have check the intake pipe's diameter is about half inch bigger then stock one, so should i get stock intake back on or just take the car to a tuning shop? so far, i have check the cmopression is good and leak down test is very good too, stays at about between 15%-20%. and i did put new plugs, Crack sensor in, but still wont help about the misfire. please, any opinion can help. I live in san francisco, any tuner shop close?
Remove the intake and remove the bov. Put stock parts back on and see if the misfire still exists. I would check the coil packs as well. I would take it to LIC Motorsports in Novato, Noah and Adam know they're stuff.
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you no what mine does the same thing only when i dont let it warm up and i have stock box and bov, mine is tuned stage 3 with new plugs, but i think it might be the coil packs
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Joined: Jul 2006
Posts: 1,069
From: Allentown,PA
Car Info: 04 WRX
I would first remove your K/N CAI and HKS BOV and return everything
to stock.Then reset your computer and drive your WRX to see if there
is a difference.You should definitley look into replacing your coil packs
and spark plugs because one or more of your coil packs could be bad and
need replacing just like your spark plugs too.
Don't get a tune yet because it would be a waste for you to get a tune
since you haven't replaced your up pipe or downpipe and have minimal
mods.Only get a tune as your last resort to fix the problem.
to stock.Then reset your computer and drive your WRX to see if there
is a difference.You should definitley look into replacing your coil packs
and spark plugs because one or more of your coil packs could be bad and
need replacing just like your spark plugs too.
Don't get a tune yet because it would be a waste for you to get a tune
since you haven't replaced your up pipe or downpipe and have minimal
mods.Only get a tune as your last resort to fix the problem.
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If you don't have a tune and the intake is a larger diameter, it could cause missfires during cold start when the ECU is in open loop. Since the ECU does not use the O2 sensor for feedback in open loop, the resulting air/fuel ratio can be be lean which can certainly cause a missfire. The intake can also lean out a/f under heavy load which can cause damage over time as well. I would recommend putting in a stock intake box and see if the problem clears up. If so, you definitely need a tune if you want to continue to run the aftermarket intake.
Thanks
-- Ed
Thanks
-- Ed
Thread Starter
Registered User
Joined: Mar 2006
Posts: 44
From: San Francisco
Car Info: 02 WRX wagen
sorry for taking so long to reply, guys, thanks alot for those info to help me out, i just got a stock intake yesterday, and try to put it in, and bov has been removed, after all that, i will reset ecu and drive it, see how does it go, if that comes out fine, then i will come to see u EQ tuning soon, thanks again guys.
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sorry for taking so long to reply, guys, thanks alot for those info to help me out, i just got a stock intake yesterday, and try to put it in, and bov has been removed, after all that, i will reset ecu and drive it, see how does it go, if that comes out fine, then i will come to see u EQ tuning soon, thanks again guys.
Thanks
-- Ed
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You say the compression is good.
What are the numbers?
Usually, if its a lean misfire, the ECM will throw a p0171 code.
If the trouble persists after switching the intake and bov, tuning will not fix the problem.
What are the numbers?
Usually, if its a lean misfire, the ECM will throw a p0171 code.
If the trouble persists after switching the intake and bov, tuning will not fix the problem.
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-- Ed
Thread Starter
Registered User
Joined: Mar 2006
Posts: 44
From: San Francisco
Car Info: 02 WRX wagen
my car has 126xxx miles on it. but compression is pretty good first pump 65 psi for NO: 1,2,4, 70psi on NO: 3 cylinder. maxi they are all around 175 psi after 6 pump. and leak down test is % at 10, 12, 10, 10, so those can proved my engine is in good compression right? because when i buy this car, the last owner already did the head to redone the valve job on it. i for got about the CEL code, but it means some time like number 1 and 3 misfire, or ramdom misfire on only when idling on cold, but 1 time it came on even the engine has been ran hot.
oh and one more thing guys, i have the OEM intake system put back on my car, my engine runs alot more smoother on idle. because with the Cold air intake, it always making the small viberation all the time, but now it is almost totally gone, not shicking anymore. so hope this oem intake can fix my problem.
when i compare the OEM intake pipe's internal diameter to the K&N intake, the K&N's internal diameter is bigger then my OEM intake pipe's outter diameter. so i think that should be the problem making my misfire, it has total almost 1/2 inch bigger then OEM intake piping. anyway, thx for all information guys.
oh and one more thing guys, i have the OEM intake system put back on my car, my engine runs alot more smoother on idle. because with the Cold air intake, it always making the small viberation all the time, but now it is almost totally gone, not shicking anymore. so hope this oem intake can fix my problem.
when i compare the OEM intake pipe's internal diameter to the K&N intake, the K&N's internal diameter is bigger then my OEM intake pipe's outter diameter. so i think that should be the problem making my misfire, it has total almost 1/2 inch bigger then OEM intake piping. anyway, thx for all information guys.
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Car Info: 2005 LGT wagon
I realize that your car is running better, but I suggest that you have all of the PCV hoses inspected when the engine is cold; once warmed up, the hoses become more pliable and seal to the metal pipes better than when cold.
Last edited by FW Motorsports; Jan 18, 2010 at 08:43 AM.
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