97 jap import wrx jerking at 4000/ 5000rpm
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This is a discussion on 97 jap import wrx jerking at 4000/ 5000rpm within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; New to this forum and really need some help to try and sort my impreza out... Ive had the car ...

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    97 jap import wrx jerking at 4000/ 5000rpm

    New to this forum and really need some help to try and sort my impreza out...
    Ive had the car for about 8 months now and was fine when i first had it, for the past 3/4 months its had this fault where i get a violent jerk when accelerating hard at about 4000/5000 rpm ,(almost like its getting too much or not enough air/fuel) once past the jerk it will carry on accelerating, it only seems to do it when warmed up..
    Ive had it in a garage where the guy there has a impreza himself , he strait away said it would be the fuel pump, he replaced the fuel pump and said he had to put in a injector aswell as the pump didnt cure the fault.
    ran ok for a few days and started playing up again, so back to the garage and he tried another pump and a coil pack, still didnt run right....
    At this point i was getting a bit fed up with chucking money at it and not cureing the actual fault...
    so to recap its had, a new fuel pump (twice)
    a injector (as it came up as a fault when he plugged it in)
    a coil pack
    and ive fitted a new fuel filter....

    please , please please someone help


    cheers
    lee

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    Registered User Merk247's Avatar
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    its hard to diag. problems over the internet..you would have to look at fuel pressure at key on running and accel for drops or dips.misfire graphic for possible misses on accel due to bad plugs fouled plugs or a bad coil. and many other parameters to really pin point the problem.
    If you have everything under control you're going too slow.
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    I'm not sure if this would have anything to do with the problem but two other mechanics have said that it sounds like it's missing , to me it sounds fine but I know nothing about cars and wouldn't know what what an engine missing would sound like anyway, something only a trained ear can tell I suppose...

    Lee

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    Registered User Merk247's Avatar
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    you really dont hear a miss as much as u feel it..
    If you have everything under control you're going too slow.
    Bugeye Mafia #218 XPT gm bcs stage 2
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  6. #5
    Registered User benson156's Avatar
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    Lee, What are your current mods if any? Do you have a boost gauge, if so what's it doing? Does the problem occur at WOT, normal driving or both?
    Hawk-eye Alliance #156

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    Thanks for replys , there are no mods that I can from apart from a stainless cat back custom pipe and has a blitz duel turbo timer which isnt connected.
    The problem only occurs when accelerating hard, normal driving it's fine , which let's face it , it's what we buy these cars for : ) , my wife says it never does it when she drives , but that's because she drives like miss daisy and rarely rakes it over 3000rpm

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    Registered User benson156's Avatar
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    Lets see, are you using the correct octane? Is there a CEL on? Man, that sucks. 97 WRX from Japan is one that I want and hate to hear that your having problems with it!
    Hawk-eye Alliance #156

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    Registered User speedracer866's Avatar
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    A faulty crank angle sensor can cause this, if you know what your scooby should sound like you will notice the difference on idle also, if the car is missing. Also have a look at the coil packs is the car idling ok?
    Blow Up And Buy Back. More Boost More Power

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    Ok guys , thanks once again for replys, as for the questions asked I just run it on normal unleaded and not sure what octane level it is , cel ?? Sorry but don't know what that is , I'm a bit clueless with cars .
    Anyway I had a friend of mine change the plugs , clean the coil and leads and used a scope to check the overall ignition system ( also checked underload ) and all ok there ,,,
    could this be a mapping/ ecu problem ...
    Another thing I should mention is when it first went to the garage it also came up "speed sensor" as a fault when plugged in , turned out the cable had snapped , not sure if this has had an affect with the problem I'm getting but thought I should mention it just incase....
    Cheers
    lee

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    The Default One SeattleJeremy's Avatar
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    Quote Originally Posted by superredeye View Post
    Ok guys , thanks once again for replys, as for the questions asked I just run it on normal unleaded and not sure what octane level it is , cel ?? Sorry but don't know what that is , I'm a bit clueless with cars .
    Anyway I had a friend of mine change the plugs , clean the coil and leads and used a scope to check the overall ignition system ( also checked underload ) and all ok there ,,,
    could this be a mapping/ ecu problem ...
    Another thing I should mention is when it first went to the garage it also came up "speed sensor" as a fault when plugged in , turned out the cable had snapped , not sure if this has had an affect with the problem I'm getting but thought I should mention it just incase....
    Cheers
    lee
    In Japan their 98 RON is close to our 93 Oct, you need to run the highest octane you can find.
    CEL = Check Engine Light.
    If you needed to clean the coil/leads, its best just to replace the cap and rotor.
    You should fix/replace the speed sensor cable.

    If your running less than 93 octane, then your engine will begin to knock at high RPM, to compensate the ECU will retard the timing, in an attempt to stop the knocking.

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    Quote Originally Posted by jeremy96gase View Post
    In Japan their 98 RON is close to our 93 Oct, you need to run the highest octane you can find.
    CEL = Check Engine Light.
    If you needed to clean the coil/leads, its best just to replace the cap and rotor.
    You should fix/replace the speed sensor cable.

    If your running less than 93 octane, then your engine will begin to knock at high RPM, to compensate the ECU will retard the timing, in an attempt to stop the knocking.
    Hi , the coil and leads were just cleaned while the plugs were done and ingnition system checked ( they checked ok on the scope used but cleaned them anyway), the snapped speed cable was replaced and cel fault was cleared by the garage on the first visit.

  13. #12
    The Default One SeattleJeremy's Avatar
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    So... have you tried using higher octane fuel?

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    Quote Originally Posted by jeremy96gase View Post
    So... have you tried using higher octane fuel?
    No ,not tried higher octane as ive been running it on the same since ive had the car , you can get a premium unleaded which has higher octane where i live .... would that really cause the problem im getting ????

    lee

  15. #14
    The Default One SeattleJeremy's Avatar
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    Where do you live?
    EDIT: Has the CEL come on again sense the shop cleared it? If so what is the code?
    Last edited by SeattleJeremy; 04-06-2010 at 12:56 PM.

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    Registered User 06scoobyrex's Avatar
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    Quote Originally Posted by superredeye View Post
    No ,not tried higher octane as ive been running it on the same since ive had the car , you can get a premium unleaded which has higher octane where i live .... would that really cause the problem im getting ????

    lee
    Yes always use 91 or higher these cars are very touchy... id look into an open source tune and try to data log it and see if you can correct it... I have a stage 1 tune on mine and it runs a lot smoother then it did stock plus the added benefit of more power too... also it could be a motor mount going bad too....
    Hawk-Eye Alliance #801
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