Very bad hesitation at high boost
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This is a discussion on Very bad hesitation at high boost within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; So I decided to change my spark plugs for preventative maintenance. After I changed them I test drove my wrx ...

  1. #1
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    Very bad hesitation at high boost

    So I decided to change my spark plugs for preventative maintenance. After I changed them I test drove my wrx and when I get on it hard at around 1 bar there is very bad hesitation(it is so bad if feels like someone is jumping on the hood of my car). I have tried to gap them multiple times from .035 to .027.

    It has been hapening for a while so it isn't bad gas, it happens in cold and hot weather. Also I have data logged and the link doesn't pull any timing and my EGTs are constant, so nothing is out of the ordinary besiedes the horible hesitation. What kind of problems does this sound like? I would appreciate any suggestions you guys have.

    UPDATE when I compared my timing and fuel maps from today after driving hard with my original maps I see it pulling and adding timing in various places by quite a few degrees.

    BTW I basically have a turbo xs stage 4 kit with a hardwired fuel pump, but I have a link ECU not a UTEC.
    Last edited by 02_silver_wagon; 09-14-2003 at 10:13 PM.

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  3. #2
    Registered User WRXin''s Avatar
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    Re: Very bad hesitation at high boost

    Originally posted by 02_silver_wagon
    So I decided to change my spark plugs for preventative maintenance. After I changed them I test drove my wrx and when I get on it hard at around 1 bar there is very bad hesitation(it is so bad if feels like someone is shaking the car). I have tried to gap them multiple times from .035 to .027.

    It has been hapening for a while so it isn't bad gas, it happens in cold and hot weather. Also I have data logged and the link doesn't pull any timing and my EGTs are constant, so nothing is out of the ordinary besiedes the horible hesitation. What kind of problems does this sound like? I would appreciate any suggestions you guys have.

    BTW I have a stage 4 kit with a hardwired fuel pump, but I have a link ECU not a UTEC.
    What kind of sparkplugs and what heat range are they?
    Fahd

    Floats like a butterfly and stings like when I pee!

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    Re: Re: Very bad hesitation at high boost

    Originally posted by WRXin'
    What kind of sparkplugs and what heat range are they?
    I tried replacing my original plugs back, but it still does the same thing. I had NGK BKR7EVX and I replaced them with NGK BKR7E plugs.

    I think I accidentaly disconected something when I tried to replace my plugs the first time.

    UPDATE I took my wrx out for a few runs to do some data logging. When I have my horible hesitations I am close to 1 bar and my boost gauge is jumping from .8 bar to 1.2 bar. The weird thing is I don't have to be at WOT, it happens if I drive it VERY VERY hard or if i downshift to pass. Here are some of my data logs compiled into one. It contains a data log from when it was running good and two from tonight.

    Please keep the ideas coming. Thank you in advance.
    Attached Files

  5. #4
    Registered User WRXin''s Avatar
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    Goodness...I wish I'm experienced enough to tell you something helpful, but I'm not. Can someone please help this guy out. I'm interested to know what the problem may be.
    Fahd

    Floats like a butterfly and stings like when I pee!

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    Registered User AREITU's Avatar
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    Bump.

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    same exact problem

    I have the exact same issue going on I think. I got the problem randomly, and my first instinct was to change the spark plugs and fuel filter, which I did with denso ik24's. The problem went away but came back. This is what happens to me. When under full boost the car hesitates, almost like a sputtering, it's not that hard of a jerk, and if the throttle isn't let off after 2-3 seconds, the CEL flashes and turns off not leaving me with any codes. This is what is confusing: The car idles fine, and can be taken all the way to redline with no problems as long as it doesn't have too much boost. I've gotten cylinder misfire codes randomly even before this problem came about. I think that might be due to a coil-pack harness that I have secured with a zip-tied and may be causing it to be intermittent. However, I do not think that is the problem. I have thought of even changing the fuel pump, but yet again I do not think that's the problem or else I wouldn't be able to start it. I just wonder if there is an issue with fuel/air or a problem with my tuning on my ecu, or wastegate, or worse, something wrong with the engine. Have you resolved your problem, does anyone have any suggestions as to what is going on? My tuning guy has no idea, and not too used to subaru's... Thanks ahead of time

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    WOW, this is an OLD post. It was a bad coil pack. I would start with that or your coil pack wiring since it sounds like you have some issues with it.

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    I'm curious as how to isolate which one it is. Just because the one I zip-tied could potentially be the f-ed up one, I don't wanna replace a 100+ harness if I'm not sure exactly which one it is. Got any ideas?

  10. #9
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    I was in the process of returning the car to stock and selling it. I put everything back to normal and used the code to isolate. You could purchase 1 new one and swap it out one-by-one. I remember seeing something about measuring the resistance across the wiring harness to rule that out. Best of luck man.

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