high rpm miss
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This is a discussion on high rpm miss within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; alright so i've got an 03 wrx with 97000km on it, i've owned it for about 3 months and in ...

  1. #1
    Registered User mexicanzero's Avatar
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    high rpm miss

    alright so i've got an 03 wrx with 97000km on it, i've owned it for about 3 months and in that time i gave it a good tune up (all oem spec parts) i've done an oil change and for the most part i've driven it pretty nicely with the odd pull to redline here and there...

    just recently (2 weeks ago?) i've been noticing that past 4000rpm power seems to drop off and past 5000rpm there is none it almost feels like i've let off the gas and its acompanied with a bit of shuddering (a missfire i would assume) this happens mostly in second gear although in first you can still feel power dropping off a bit and it seems the more gas i give it the worse it looses power...

    yesterday on a pull to 6000rpm having the same symptoms described above i got my first engine light!! yayy!! not...
    i scoped it and it showed missfire on cyl 1 and 2

    i finally got my boost gauge hooked up today and on the way home i realised that i'm not really hitting full boost, highest i see in 1st is 5-7psi in second i barely hit 10 maybe 12 and its not even until like 4500rpm i think...

    can a boost leak cause a missfire? i'd say it feels like a boost leak, i've had a lot of boost leaks in my 92 legacy turbo but they never caused missfiring and pretty much always caused idling issues and low vaccum too, my idle is rock steady at 750 with 20-21inhg...

    i'm gona attempt to spend a good chunk of saturday or sunday morning pulling plugs/coils and swapping them over just to cancel those options out although i doubt thats it and i'll pull the intercooler too to see what the y pipe looks like...

    thanks in advance!!
    -Alex

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  3. #2
    Registered User benson156's Avatar
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    This happened to me when I had my Golf, it ended up being a coil. Hope you get it all figured out. Good luck.

  4. #3
    Registered User mexicanzero's Avatar
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    the main reason i doubt it being coils or plugs is the fact that 2 cyls showed missing. them having 2 separate coils the chance of 2 plugs or 2 coils going at the same time is very very slim.

    i'm actually starting to think it may have had to do with a batch of bad gas because i think it started a bit under 2 weeks ago (i usually go through a tank of gas in about 2 weeks). yesterday i filled up again, today on the way to work i couldnt get the engine light to come back on power was still down but the engine didnt seem to be missing anymore.
    on the way home i did probably 4 decent 2nd gear pulls and i think only one of them felt sluggish, the others felt great although i still wasnt hitting full boost... i'd assume in 1st gear i wont see full boost but what about in second? shouldnt i see it by 3000 rpm? or 3rd?

    i'm still gonna check for boost leaks and i'll do an ecu reset this weekend just for fun and see what happens
    -Alex

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    i had a similar problem and it turned out being the crank position sensor. pretty easy to replace and fairly cheap($30 i think). worth a shot if you just wanna throw some parts at it and definitely cheaper than coils.

  6. #5
    Registered User benson156's Avatar
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    Did you find out what was going on with you car man?

  7. #6
    Registered User mexicanzero's Avatar
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    hah! i figured it out i finally got the intercooler off today and i dont know if the p.o. f'd it up or what but the last person that had the intercooler off didnt know what they were doing (this was my first time having it off this car)
    one of the bolts bolting the metal elbow to the intercooler was not there and the other was in sideways waay crossthreaded and not in all the way... so basically there was a half inch gap between the elbow and the intercooler where air could go wherever it wanted to...
    surprising thing is that the car ran perfect (including idle) up to about 3500 rpms i even saw 12 psi in second gear although it took way too long to get there... i just replaced the 2 bolts and rethreaded the threads that were messed up and voila
    the air leak must have been causing it to run waay rich on boost since air was leaking out and thus causing missfiring...

    deifnitely the most interesting boost leak i've ever met

    the car obviously had a bit of a leak ever since i got it cuz its never been this fast... i mean it was quick, surprised all of my buddies buut woah! now its insane! i'm so excited to go stage 2 in the spring now you have no idea!

    thanks though eh guys!

    -Alex

  8. #7
    Registered User benson156's Avatar
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    Good dude, im glad you got it figured out. Pretty sure that nobody would have guessed that.

  9. #8
    Registered User mexicanzero's Avatar
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    hah thanks, yeah i'm just happy it was that simple
    theres nothing like finally having your dream car after 5 years of dreaming and then it not running right...
    i think i'll give it an oil change tomorrow even though i'm not due yet just to spoil it a little bit

    -Alex

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