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Thread: Spark dwell time

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    Spark dwell time

    Dear HPT, I currently have a engine the seems to blow out the spark at around 22psi resulting in a miss fire. I can fix this by going down to .6mm plug gap or running less boost but I would rather fix it by increasing spark dwell time. I saw that I can increase the dwell time globally across all rpm and loads which would probably fix the miss fire but it would reduce life of the coils. Is there possibly an existing dwell table calibration map in the ECU that could be added to HPT to allow an increase to dwell time at higher load or boost?

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    HPT Employee Eric@HPTuners's Avatar
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    Eric Brooks
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    Benny higher than ~22psi is very capable at stock dwell time and at ~0.75-0.8mm its your coils that are struggling and very common, increasing dwell time imho is going to decrease the coils life at a rapid rate for obvious reasons
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    Quote Originally Posted by JETURBO View Post
    Benny higher than ~22psi is very capable at stock dwell time and at ~0.75-0.8mm its your coils that are struggling and very common, increasing dwell time imho is going to decrease the coils life at a rapid rate for obvious reasons
    I understand, that's why I was thinking about only increasing dwell time at WOT which doesn't happen often. I have fitted new genuine ford coils and also tried the upgraded coils from autotrad and the problem is still there. Maybe I have another problem.

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    I don't think anyone has ever had much luck finding a replacement that outperforms the stock Coils, I've just fitted one of those Herrod spark Boosters to mine, it is ok, But I would got the ICE ones. The Herrod ones are a nice fit though, I haven't gapped my plugs back up to make the most of it though which is probably half my cold start issue on E85

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    Just as a point to take note genuine coils have been found to have a reduction of their initial capacity after small work such as 5-10,000kms

    I think u may have another issue

    Are u using "genuine" ford turbo plugs ?
    What fuel are u trying +22psi on ?
    What turbo and when are u seeing big boost ?
    FG F6 400+RWKW .....10.9 @ 132mph.... FIRST 10sec F6 in SA ( sold )
    DYNO DYNAMICS 1200hp ...... Tuning weapon..... ( sold )
    OFFICIAL JONNY TIG INDUSTRIES SUPPLIER ..... Biggest and lightest intercoolers for B and F falcons
    SUBARU BRZ ......AVO TURBO KIT coming......soon
    VF R8 CLUBSPORT SV...... 340FWKW.....ASE BIG SINGLE KIT .....one day

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    Quote Originally Posted by Eric@HPTuners View Post
    What is your OSID?
    Hi Eric, my OS ID is HACCDD3

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    HPT Employee Eric@HPTuners's Avatar
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    Quote Originally Posted by benny-4000 View Post
    Hi Eric, my OS ID is HACCDD3
    Wait 10 minutes and update.
    Eric Brooks
    HP Tuners, LLC

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    The APS PCM has a load based table for dwell whereas the ABU/ASU don't. Everyone tells me the Dwell is a fixed value operating in open loop but based on info presented in another forum from some years ago I'm not convinced. Eric you probably know what I'm on about, do you know if the dwell is closed loop targeting a predefined coil amperage....with the tables we see simply being the open loop feed forward value?

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    HPT Employee Eric@HPTuners's Avatar
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    Quote Originally Posted by IH8TOADS View Post
    The APS PCM has a load based table for dwell whereas the ABU/ASU don't. Everyone tells me the Dwell is a fixed value operating in open loop but based on info presented in another forum from some years ago I'm not convinced. Eric you probably know what I'm on about, do you know if the dwell is closed loop targeting a predefined coil amperage....with the tables we see simply being the open loop feed forward value?
    It's closed loop on the EEC-V, but the PowerPC has the controls, as I have added to the above OS. (It's in a few of the OS), if you need it in your OS, let me know what it is.
    Eric Brooks
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    Thanks Eric, much appreciated.

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    I have tried both NGK PFR7B and NGK BRK6EIX plugs, both with 0.6mm gap and had a similar result with missfire although if I lean it out the PFR7B would knock before the BRK6EIX.
    I am using 98 octane fuel
    My turbo is the standard garret GT3584R with standard ford housing, enlarged waste gate port, larger waste gate flapper valve & 12PSI waste gate actuator. I am getting 22PSI as soon as I can make it (approx 3000RPM) and then tapering boost off to 18 PSI at 6000RPM.
    With my setup I can not actually keep boost under 18 PSI
    At 3000RPM the ignition advance is down to 4 degrees in the borderline knock table to reduce likely hood of a knock but I think leaving the timing this late at 22PSI is making it difficult for the spark to light.

    Quote Originally Posted by JETURBO View Post
    Just as a point to take note genuine coils have been found to have a reduction of their initial capacity after small work such as 5-10,000kms

    I think u may have another issue

    Are u using "genuine" ford turbo plugs ?
    What fuel are u trying +22psi on ?
    What turbo and when are u seeing big boost ?
    Last edited by benny-4000; 07-24-2014 at 05:44 AM. Reason: mistake in plug no

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    you need a better port job on the wastegate if you are trying to get the boost lower but can't

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    Quote Originally Posted by Huddo View Post
    you need a better port job on the wastegate if you are trying to get the boost lower but can't
    HaHa, There is nothing left to port, if the port was any bigger, the flapper valve will go through it.

    My exhaust is custom and flows very well and my turbo has custom bearings in it that seem to allow it to spool up faster than standard.

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    Who did the port job? I've see some small port jobs out perform larger ones with better flow. What is the actuator rated at and then what have you set the actuator preload/crack pressure at?

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    Hi mate, you sound pretty cluey so apologies if you know this already, but the entrance to the gate is important. Have you profiled the housing to better direct exhaust has into the gate?

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    A common misteak is lowering timing levels to excessively low amounts to allow for boost spike, believe it or not a better timing selection will actually help maintain a boost spike especially in the mid

    If u cant see lower than 18psi at the end your port job is wrong clean and clear ( assuming your actuator is set corectly )

    Just to give u some idea a GTX3582 ( more flow than a stock F6 or b series turbo) can have as low as 17psi at the end even after cranking 22psi in early if the port job is done correctly !!

    To me it sounds like you have the preload way to strong and a cruddy port job
    FG F6 400+RWKW .....10.9 @ 132mph.... FIRST 10sec F6 in SA ( sold )
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    OFFICIAL JONNY TIG INDUSTRIES SUPPLIER ..... Biggest and lightest intercoolers for B and F falcons
    SUBARU BRZ ......AVO TURBO KIT coming......soon
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    Mmmmm misteak

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    Quote Originally Posted by 45T-XR View Post
    Who did the port job? I've see some small port jobs out perform larger ones with better flow. What is the actuator rated at and then what have you set the actuator preload/crack pressure at?
    I did the port job about 4 years ago but it is a straight hole only.

    The waste gate actuator is 12 PSI

    The preload is set approx 1mm

    It has been working fine until I rebuilt the turbo CHRA with ceramic bearings. Now it spools up harder and earlier.

    I take your point on the entrance to the gate though, I could definately improve on the straight hole.

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    Quote Originally Posted by JETURBO View Post
    A common misteak is lowering timing levels to excessively low amounts to allow for boost spike, believe it or not a better timing selection will actually help maintain a boost spike especially in the mid

    If u cant see lower than 18psi at the end your port job is wrong clean and clear ( assuming your actuator is set corectly )

    Just to give u some idea a GTX3582 ( more flow than a stock F6 or b series turbo) can have as low as 17psi at the end even after cranking 22psi in early if the port job is done correctly !!

    To me it sounds like you have the preload way to strong and a cruddy port job
    It makes sense what you are saying about excessively low timing. i will experiment.

    The 18 PSI that i cant keep below atm is at around 3000RPM.

    I noticed this minimum 18PSI @ 3000RPM issue when I disconnected the boost solenoid from the waste gate actuator after I rebuilt the CHRA. Actually I dont mind and it is not a problem as I usually have 22PSI at approx 3000RPM anyway.