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Thread: Engine bucking???

  1. #1
    Join Date
    Apr 2004
    Location
    Wisconsin
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    705

    Engine bucking???

    My car has a bucking type feeling ONLY between 40-60 mph in OD. All my COP seem fine, plugs are good. I checked my TPS and its working porperly. Its only when the car is at part throtle or costing, under load its fine. Any Ideas????????????
    #1724 of 3214 Built 02/13/2004
    2004 Marauder black/moonroof
    SCT flip chip, 4:10's, lowered, big brake kit
    Kenwood KDC-X790 & 4 Kenwood speakers, 10" Sub
    Addco tube sway bars & performance shocks, Metco's
    Zex dry nitrous kit, Full SW Exhaust Kit, PI 3000 Stall
    5.0L Stroker assembly, Self installed!
    E.T. on drag radial tires: 12.270 @ 111.16 & 1.66 60'
    One off custom Hood all steel too.
    SOON TO BE Vortech supercharged

    Ryan Schmuki
    2003 Marauder, black with 4.10s n tune (sold)
    1968 Fairlane 347 built stroker(fast)
    1963 Galaxie 390 auto
    2010 Mercury Milan
    2019 Taurus Limited

  2. #2
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    St. John, IN
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    Did you have the car tuned after the new engine was installed?

  3. #3
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    Did you have your kit balanced prior to assembly.

    All 4.6 modular motors are internally balanced. The 3.75" stroker crank is considered a 5.0L (301cid with .020 over bore) and requires balancing. Most machine shops and engine builders have dynamic balancing as an option. But to Mustang & Fords, dynamic balancing and extreme attention to detail are mandatory steps in an engine build. Dynamic balancing is crucial to engine smoothness and survival because vibration (any vibration, no matter how small) kills. It shakes things to pieces. Not balancing an engine is foolish, courting disaster at worst and shortening engine life at best.

    When you dynamic balance an engine, you balance the crankshaft (just as you would tires and wheels) for smooth operation. Then, you balance connecting rods and pistons to match the crankshaft balance. Do this every time you build an engine. If you have this problem a tune will not fix the issue.
    Last edited by merc; 07-15-2008 at 07:20 AM.


    James Brown #140 "Say It Loud" Except in Bristol
    Merc's Garage
    MagnaFuel ProTuner Series 750 MP-1403
    Stainless Steel Works full exhaust
    SCT Advantage III Ford Pro Racer Software
    600.59 rwhp 559.91 Torque @ 20 lbs Boost
    2.3 Whipple Intercooled Supercharger
    BC Automotive Stage4 transmission
    03 Terminator built by Chris Vining

  4. #4
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    I second what merc said.
    If you bought a kit and 'bolted it in' this could be your problem.

    But if you did not have the car tuned after the 5.0, go this route first.

  5. #5
    Join Date
    Apr 2004
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    Wisconsin
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    Quote Originally Posted by Zack View Post
    Did you have the car tuned after the new engine was installed?
    DUH yes I had it tuned.
    #1724 of 3214 Built 02/13/2004
    2004 Marauder black/moonroof
    SCT flip chip, 4:10's, lowered, big brake kit
    Kenwood KDC-X790 & 4 Kenwood speakers, 10" Sub
    Addco tube sway bars & performance shocks, Metco's
    Zex dry nitrous kit, Full SW Exhaust Kit, PI 3000 Stall
    5.0L Stroker assembly, Self installed!
    E.T. on drag radial tires: 12.270 @ 111.16 & 1.66 60'
    One off custom Hood all steel too.
    SOON TO BE Vortech supercharged

    Ryan Schmuki
    2003 Marauder, black with 4.10s n tune (sold)
    1968 Fairlane 347 built stroker(fast)
    1963 Galaxie 390 auto
    2010 Mercury Milan
    2019 Taurus Limited

  6. #6
    Join Date
    Apr 2004
    Location
    Wisconsin
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    47
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    Quote Originally Posted by merc View Post
    Did you have your kit balanced prior to assembly.

    All 4.6 modular motors are internally balanced. The 3.75" stroker crank is considered a 5.0L (301cid with .020 over bore) and requires balancing. Most machine shops and engine builders have dynamic balancing as an option. But to Mustang & Fords, dynamic balancing and extreme attention to detail are mandatory steps in an engine build. Dynamic balancing is crucial to engine smoothness and survival because vibration (any vibration, no matter how small) kills. It shakes things to pieces. Not balancing an engine is foolish, courting disaster at worst and shortening engine life at best.

    When you dynamic balance an engine, you balance the crankshaft (just as you would tires and wheels) for smooth operation. Then, you balance connecting rods and pistons to match the crankshaft balance. Do this every time you build an engine. If you have this problem a tune will not fix the issue.
    Yes it was properly balanced. I reseached the hell out of everything befor I bought it, I have built plenty of engines so I know what I am doing. Its not a vibration, like I said the egnine surges alittle but has good power. I
    #1724 of 3214 Built 02/13/2004
    2004 Marauder black/moonroof
    SCT flip chip, 4:10's, lowered, big brake kit
    Kenwood KDC-X790 & 4 Kenwood speakers, 10" Sub
    Addco tube sway bars & performance shocks, Metco's
    Zex dry nitrous kit, Full SW Exhaust Kit, PI 3000 Stall
    5.0L Stroker assembly, Self installed!
    E.T. on drag radial tires: 12.270 @ 111.16 & 1.66 60'
    One off custom Hood all steel too.
    SOON TO BE Vortech supercharged

    Ryan Schmuki
    2003 Marauder, black with 4.10s n tune (sold)
    1968 Fairlane 347 built stroker(fast)
    1963 Galaxie 390 auto
    2010 Mercury Milan
    2019 Taurus Limited

  7. #7
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    St. John, IN
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    Are you running the same plug gap with and without the Nitrous?

  8. #8

    surging

    am having the same problem since we as country went to 10 percent
    ethanol!. i believe it has something to do with the o2 sensor . just a guess. we use to use ethanol to pas emission inspections years ago when we did not have time for a thirty to forty min. warm up and it worked.
    will run out this tank and fill with gas i have stored for my generator and
    post again. or you could run almost empty and try some aviation fuel?.
    good luck by the way i`v lost two M.P.G. since the change....

  9. #9
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    Quote Originally Posted by fairlane347 View Post
    Yes it was properly balanced. I reseached the hell out of everything befor I bought it, I have built plenty of engines so I know what I am doing. Its not a vibration, like I said the egnine surges alittle but has good power. I
    If you are ruling out the mechanical aspect then let's look at spark. Also give Darrin a call concerning the Over Drive, he might have some insight. What are the RPM's when the engine begins to buck? FYI engines vibrate and transmissions buck.
    Last edited by merc; 07-15-2008 at 09:23 AM.


    James Brown #140 "Say It Loud" Except in Bristol
    Merc's Garage
    MagnaFuel ProTuner Series 750 MP-1403
    Stainless Steel Works full exhaust
    SCT Advantage III Ford Pro Racer Software
    600.59 rwhp 559.91 Torque @ 20 lbs Boost
    2.3 Whipple Intercooled Supercharger
    BC Automotive Stage4 transmission
    03 Terminator built by Chris Vining

  10. #10
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    Quote Originally Posted by Frank Androski View Post
    am having the same problem since we as country went to 10 percent
    ethanol!. i believe it has something to do with the o2 sensor . just a guess. we use to use ethanol to pas emission inspections years ago when we did not have time for a thirty to forty min. warm up and it worked.
    will run out this tank and fill with gas i have stored for my generator and
    post again. or you could run almost empty and try some aviation fuel?.
    good luck by the way i`v lost two M.P.G. since the change....
    I have been running the 10% E and it has not changed.
    #1724 of 3214 Built 02/13/2004
    2004 Marauder black/moonroof
    SCT flip chip, 4:10's, lowered, big brake kit
    Kenwood KDC-X790 & 4 Kenwood speakers, 10" Sub
    Addco tube sway bars & performance shocks, Metco's
    Zex dry nitrous kit, Full SW Exhaust Kit, PI 3000 Stall
    5.0L Stroker assembly, Self installed!
    E.T. on drag radial tires: 12.270 @ 111.16 & 1.66 60'
    One off custom Hood all steel too.
    SOON TO BE Vortech supercharged

    Ryan Schmuki
    2003 Marauder, black with 4.10s n tune (sold)
    1968 Fairlane 347 built stroker(fast)
    1963 Galaxie 390 auto
    2010 Mercury Milan
    2019 Taurus Limited

  11. #11
    Join Date
    Apr 2004
    Location
    Wisconsin
    Age
    47
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    705
    Quote Originally Posted by merc View Post
    If you are ruling out the mechanical aspect then let's look at spark. Also give Darrin a call concerning the Over Drive, he might have some insight. What are the RPM's when the engine begins to buck? FYI engines vibrate and transmissions buck.
    i don't remember at what rpm I will have to look.
    #1724 of 3214 Built 02/13/2004
    2004 Marauder black/moonroof
    SCT flip chip, 4:10's, lowered, big brake kit
    Kenwood KDC-X790 & 4 Kenwood speakers, 10" Sub
    Addco tube sway bars & performance shocks, Metco's
    Zex dry nitrous kit, Full SW Exhaust Kit, PI 3000 Stall
    5.0L Stroker assembly, Self installed!
    E.T. on drag radial tires: 12.270 @ 111.16 & 1.66 60'
    One off custom Hood all steel too.
    SOON TO BE Vortech supercharged

    Ryan Schmuki
    2003 Marauder, black with 4.10s n tune (sold)
    1968 Fairlane 347 built stroker(fast)
    1963 Galaxie 390 auto
    2010 Mercury Milan
    2019 Taurus Limited

  12. #12
    Join Date
    Sep 2005
    Location
    Buffalo, NY
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    59
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    I had an 89 Escort GT that bucked like hell at 35 to 55 MPH. It had a bunch of sensors replaced over time. I think the MAF, TPS and O2's.... It was long drawn out process to solve, but eventually we got it.

    Sounds like a metering issue to me, and don't disagree it is in the engine...
    Built: 3/16/2004
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  13. #13
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    Quote Originally Posted by fairlane347 View Post
    i don't remember at what rpm I will have to look.
    You might have a good engine tuner but the art to getting to the Marauder to sing is in the transmission. Low RPM's in high gear will cause your bucking problem. Since our transmissions are electronic controlled then it would be in the tune. What's your rear gear ratio?


    James Brown #140 "Say It Loud" Except in Bristol
    Merc's Garage
    MagnaFuel ProTuner Series 750 MP-1403
    Stainless Steel Works full exhaust
    SCT Advantage III Ford Pro Racer Software
    600.59 rwhp 559.91 Torque @ 20 lbs Boost
    2.3 Whipple Intercooled Supercharger
    BC Automotive Stage4 transmission
    03 Terminator built by Chris Vining

  14. #14
    Quote Originally Posted by fairlane347 View Post
    I have been running the 10% E and it has not changed.
    "also have a new hyundai 6000 mi. was getting 27 mpg. hwy , now down to 24. same driver, different gas . the cumberland farms station was the last here to implement --.-- citrus county fl.
    if your not affected ,i am glad for you , but if you know somethink i don`t
    i hope you will share ..
    the hyundai runs like it was on rails , but it`s the marauder that lays the track, got to love it ,. thanks

  15. #15
    Who went to 10% e?

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