rough idle
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This is a discussion on rough idle within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; the other day i got a cel so i brought it into a family friends shop. i was having mis ...

  1. #1
    Registered User Bizarre11's Avatar
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    rough idle

    the other day i got a cel so i brought it into a family friends shop. i was having mis fires in cylinders 1,3, and 4. even though this happened the car ran fine and i could not notice any difference in driving. when i brought it in they checked the spark plugs and said it was fine, than he mentioned that maybe the injectors were dirty. but wat is even worse is that he did a vacume test and said that i may have a bent valve. i really do not know wat this means or how this could have happened if this is the problem.
    for now he filled my tank and put a high concentrated liquid in the car to clean everything out. since than i have noticed the cars idle is rough and the turbo gague is sort of bouncing. anyone know wat the problem could be?
    2005 wrx, stock 50,000 miles

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    Registered User Bizarre11's Avatar
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    anyone?

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    Moderator Donkey's Avatar
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    Did you not contact your friend about this problem?Maybe he put the wrong octane gas.You need to use 93 or at a very minimum 91.Since he has actually seen/worked on the car he would have maybe a better idea and has the ability to physically troubleshoot the car.Is the check engine light on?The gauge is bouncing because of the rough idle probably.You gave very little details on how the car is running overall after taking it to your friend.The more details,the better.....
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    Registered User Bizarre11's Avatar
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    there is no check engine light anymore after i brought it to the shop. the car is driving fine. it has all top end and low end power. the only thing that still has me a little worried is the idle. when i am sitting at a light in neutral the idle fluctuates. the rpm's are staying at 500 but the vaccume gauge is bouncing a little bit. i will post a video to show you exactly wat is happening.

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    Registered User Bizarre11's Avatar
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    YouTube - 104 1401

    sound quality is crappy, and i couldnt get the camera to focus on the gauge but you should be able to tell wat is going on.

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    Registered User jimenezp's Avatar
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    Check all your vaccum lines. Id start there. Also clean out your MAF sensor, if its really dirty it can cause your car to idle rough and run like crap. Any mods?? Run a bottle of fuel injector cleaner through the car maybe that will help..

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    Registered User jimenezp's Avatar
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    Quote Originally Posted by Donkey View Post
    Did you not contact your friend about this problem?Maybe he put the wrong octane gas.You need to use 93 or at a very minimum 91.Since he has actually seen/worked on the car he would have maybe a better idea and has the ability to physically troubleshoot the car.Is the check engine light on?The gauge is bouncing because of the rough idle probably.You gave very little details on how the car is running overall after taking it to your friend.The more details,the better.....
    +1 make sure its the right gas

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    i have a simaler prob

    i am having a simmilar prob in my 02 wagon i blew it a few months back had it rebuild by a trusted mech and it hasent been right since. at idle the boost (vac) needle is bouncing about 1-2 in vac. if i go into a parking lot get in 2nd gear and idle(in gear) it kind of bucks across the parking lot bucking is small and i can feel it in acceleration also. when i boost i get a P0103 (MAF high in put) cel. my mech said that the g/sec are a little high At 3.6-3.7 at idle. vac lines are fine changed the fuel filter maf sen is brand new intake presure sen new all coils are new plugs are new. i use 93 oct always. stock flash runs ok is just rough. list fo mods aem short ram intake, big 16g turbo, act light weight fly wheel. centerforce dual friction cluch. turbo xs man boost controler. any help is apreciated thank you

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    Moderator Donkey's Avatar
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    Quote Originally Posted by rbarrett36 View Post
    i am having a simmilar prob in my 02 wagon i blew it a few months back had it rebuild by a trusted mech and it hasent been right since. at idle the boost (vac) needle is bouncing about 1-2 in vac.
    At idle vacuum should be 18-20".Sounds like you have a vacuum leak.

    Quote Originally Posted by rbarrett36 View Post
    if i go into a parking lot get in 2nd gear and idle(in gear) it kind of bucks across the parking lot bucking is small and i can feel it in acceleration also. when i boost i get a P0103 (MAF high in put) cel. my mech said that the g/sec are a little high At 3.6-3.7 at idle. vac lines are fine changed the fuel filter maf sen is brand new intake presure sen new all coils are new plugs are new. i use 93 oct always. stock flash runs ok is just rough. list fo mods aem short ram intake, big 16g turbo
    Are you saying your running a big 16G with a stock ROM and no injectors?I hope not as you cannot run a bigger turbo without engine management and larger injectors.It really sounds like you have a vacuum leak.Could even be a leak at the intake manifold or TGV's.
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    i had AP 740ccinj couldnt get it to run right put the stocks back in and wached the a/f and it never went any leaner that 11. at full boost. my next step was going to b sti pinks and fuel wal255 fuel pump. then get it on a dyno. does that sound like the right direction?

    thanks for the help

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    i forgot to add the vac avg about 18-22

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    Moderator Donkey's Avatar
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    Quote Originally Posted by rbarrett36 View Post
    i had AP 740ccinj couldnt get it to run right put thestocks back in and wached the a/f and it never went any leaner that 11. at full boost. my next step was going to b sti pinks and fuel wal255 fuel pump. then get it on a dyno. does that sound like the right direction?

    thanks for the help
    How much boost were you running? Were you using the stock front 02 sensor to reference the AFR?FYI the stock primary O2 sensor is not a true wideband.I max out the stock injectors on the stock turbo (TD04L-13t) which flows 400cfm@1bar.A big 16G flows 550cfm@1bar.
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    i had it as high as 22 lbs with no fuel cut and staying at 11.0a/f. i am using an innovate Lc-1. i only ran it at 22 lbs for a short time then blew it. be for i was at 15 lbs im thinking i may have a bad or dirty injector. when it blew it was b/c of detonation broke the piston lands.

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    Moderator Donkey's Avatar
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    Quote Originally Posted by rbarrett36 View Post
    i had it as high as 22 lbs with no fuel cut and staying at 11.0a/f. i am using an innovate Lc-1. i only ran it at 22 lbs for a short time then blew it. be for i was at 15 lbs im thinking i may have a bad or dirty injector. when it blew it was b/c of detonation broke the piston lands.
    There is no way you were running a big 16G 22psi with stock injectors and not leaning out.I'm guessing your LC-1 was way out of calibration.I max out the stock injectors on the stock turbo..........
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