wrx jolting in 2nd gear at 4 or 5k rpms
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This is a discussion on wrx jolting in 2nd gear at 4 or 5k rpms within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I have a vf39, sti blue injectors, walbro fuel pump, and the cobb ots map on my 2003 wrx. Last ...

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    Supporting Member yamaha_rider619's Avatar
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    wrx jolting in 2nd gear at 4 or 5k / terrible idle

    I have a vf39, sti blue injectors, walbro fuel pump, and the cobb ots map on my 2003 wrx. Last week I put on a spt intake and everything has been good. Today I was driving, in the harsh rain, and my car started jolting in 2nd gear at about 4 or 5k rpms. My car was also idling bad, like it was going to die. The filter is not wet from the rain.
    Last edited by yamaha_rider619; 05-12-2011 at 08:45 AM.
    Josh
    2003 Subaru Wrx Vf39'd
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    He simply abides. SD_GR's Avatar
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    No CEL though? Did you install the MAF correctly and is its harness still on tight? The SPT should in and of itself be fairly innocuous.
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    Supporting Member yamaha_rider619's Avatar
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    There is no cel. There is only one way to install the maf, but yes I checked it and it is tight.
    Josh
    2003 Subaru Wrx Vf39'd
    Bugeye mafia #300

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    UnBanned Sinister's Avatar
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    Just to keep any future seekers in the loop:
    Talked to Josh on the phone. He reset his ECU, and now there's no jolting. My immediate guess is a lean condition from the new intake. He said he's checked and double checked the intake, and that nothing was touched besides the intake. I asked if he has an aftermarket turbo inlet, or if the stocker has been cracked. He said the turbo inlet is brand spankin new from subaru so it shouldn't be the problem. Since the ECU reset stopped the jolting, that means his timing has been retarded enough that he's not getting timing pulled by the ECU for knocking. This is because his DAM (Dynamic Advance Multiplier) has been reset to 0.

    Josh has AccessRace and Cobb has instructions in their "Tuning Guide" on how to do some MAF Scaling.

    Here's the link Josh:
    AccessECU Tuning Guide and Worksheet for Subarus

    And in the AccessECU Tuning guide the following terms have been changed:
    "Fuel Injector Boost Error Trim" is now "Tip-in Enrichment Compensation (Boost Error)"
    "A/F Trim Immediate" is now "A/F Correction #1"
    "A/F Trim Learned" is now "A/F Learning #1"
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    Supporting Member yamaha_rider619's Avatar
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    Kevin, thanks for the help and doing all the leg work for me!

    I have a feeling the spt intake definitely needs scaling, because when I was at WOT I watched my boost gauge shake and at the same time I could here the intake sucking so hard it seemed to suck in and out.

    This MAF scaling is very complicated though...
    Josh
    2003 Subaru Wrx Vf39'd
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    Supporting Member yamaha_rider619's Avatar
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    Well last night I started my car at about midnight and it ran worse than it did all day. At idle it tried to die and when taking off I had to rev the crap out of it, at 3k rpms, to even get it to move. Then once driving it was very jerky the whole way home.
    Josh
    2003 Subaru Wrx Vf39'd
    Bugeye mafia #300

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    Registered User mudferret's Avatar
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    Have you logged FBKC and FLKC?
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    MMVI WRX - VF43 Airboy Tuned @ 3500'

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    Supporting Member yamaha_rider619's Avatar
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    It's hard to log anything as the car barely wants to run. Weirdest thing is this issue happened overnight.


    Dynamic Adv., Fine Knock Learn, and Feedback Knock are 0 the whole log, saved space and removed them.


    Here is a datalog of today at idle, the car died twice at idle:datalog6.pdf
    Attached Files
    Last edited by yamaha_rider619; 05-12-2011 at 09:05 AM.
    Josh
    2003 Subaru Wrx Vf39'd
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    UnBanned Sinister's Avatar
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    I can't see the datalog in tapatalk, but I think you need to reinstall your stock airbox and see what happens...
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  11. #10
    Supporting Member yamaha_rider619's Avatar
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    I just got a replacement stock intake, now am going to buy a air filter. Will post updates...
    Josh
    2003 Subaru Wrx Vf39'd
    Bugeye mafia #300

  12. #11
    Supporting Member yamaha_rider619's Avatar
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    The hard rain some how got on only the bottom of the filter, so I could not see it. Problem solved.
    Josh
    2003 Subaru Wrx Vf39'd
    Bugeye mafia #300

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