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Discussion in 'Fox 5.0 Mustang Tech' started by SilverBullit, Sep 24, 2003.


  1. SilverBullit

    SilverBullit Founding Member

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    I recently put a new engine in my car. After the install I performed all the correct break-in procedures. I've found that whenever in first gear and you nail it, it cuts out and seems to have no power. After you shift into second it still wants to cut out a little and then clears up after mid second gear the rest of the gears seem fine, but if your just cruisin at the same RPM it cuts out a little every now and then. It revs fine when its in neutral and there are no signs of cutting out or anything, anybody have any ideas?

    Another problem I have is that when you go past 55 mph the car and shifter start shaking real bad. If under full acceleration it doesn't do it very badly until you let off the gas and just start coasting, then the shifter starts shaking like a SOB.

    Any help is greatly appreciated!

    Thanx
    Casey
  2. go-stang5.0

    go-stang5.0 New Member

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    I dunno about the cutting out part but the vibration is probably due to the flywheel being out of balance. Do you have the correct one for your application, also same for the harmonic balancer...is that the correct balance? Its got to be one of the two.
  3. jerry beach

    jerry beach Founding Member

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    Is the shaking in the shifter still there when you let it idle at 55mph in nuetral? If so, its the DS prolly. My shifter shook badly when I had a dead miss, caused by a bad inj., but you prob sounds very different. How is the idle quality? Is there a miss present at idle? I am thinking maybe PIP sensor or TFI, since it seems to be intermittant. Did you pull codes? If not do this first. May or may not tell you whats up.
  4. matm347

    matm347 Founding Member

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    Did you convert your car to MAF? If not I would suspect you have gone beyond the limits of the stock speed density. SD has never liked major mods like you have (H/C/I).

    The vibration sounds like a bad U-joint on you DS. Everything is OK and in balance while under load, but when you let off the throttle and do some compression breaking the U-joint backs out of alignment which throws it off balance. Do you hear any clanking sound when tapping the throttle while in gear?
  5. 2000xp8

    2000xp8 Mustang Master

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    I'd say the vibration is the drive shaft also. 150 for a motorsport aluminum driveshaft is a good investment.
  6. seijirou

    seijirou Founding Member

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    suspect ignition with the cutting out/coughing.

    suspect driveshaft with your vibration problems
  7. 88CougarMan

    88CougarMan Founding Member

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    Does it feel like a hesitation?
  8. SilverBullit

    SilverBullit Founding Member

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    I've replaced both u-joints and that didn't help the problem. I have not converted to MAF I still retain SD. The car doesn't miss at idle only when going a steady speed at it missed every now and then. Whenever you nail it in first gear it want to cut out and just not go, it does this most of the time but sometimes it doesn't, and when it doesn't it runs like a bat out of hell (solid 12 sec car) and even when it does it will still probabley run a mid 13.
  9. SilverBullit

    SilverBullit Founding Member

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  10. SilverBullit

    SilverBullit Founding Member

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  11. SilverBullit

    SilverBullit Founding Member

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    Surely someone has some ideas of what's going on.
  12. Hourang

    Hourang New Member

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    maybe fuel pump :shrug: is it a stock pump(it doesnt say in your sig)? i would also check timing and your codes. vibration could also be fuel or ignition related, im doubting the driveshaft being the culprit since you never said it did it before the new motor. good luck with the gremlin:)
  13. randysstang

    randysstang New Member

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    it sounds like timing
  14. SilverBullit

    SilverBullit Founding Member

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    When I put the new engine in I also put in a BBK 255 lph intake pump. When I put the new engine in one of my buds stepped on my damn timing indicator, we tried to bend it back best we could. I've also noticed that if you get on it in second and third when you get up to about 85 mph and let off the gas it doesn't shake or vibrate anything for a few seconds, then it starts shaking really bad until you slow back down to around 55 mph.

    Thanks
  15. VG30DE

    VG30DE Founding Member

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    almost positive its driveshaft being out of balance. About the hesitation, check for vacuum leaks, check the MAP sensor, maybe replace it, make sure the timing advance pill is tight and in place, and try advancing the timing a little. Run the EEC diag and see if throws any codes at you, that always helps. It could also be cam roll, are you sure the cam is on the right tooth on the chain, have you run this agressive of a cam with SD before the motor was replaced? It might need a custon tune to iron out cam issues? I'm just throwing whatever I can think of at you...
  16. SilverBullit

    SilverBullit Founding Member

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    I've replaced the driveshaft with an new aluminum unit and it has practically stopped every bit of vibration! It rides really smooth now all the way through hard accelerating. I still have the bogging/cutting out issue in first gear though, someone mention checking the MAP sensor, how do you that. I've checked for vacuum leaks and can't seem to find any.

    Casey
  17. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Dump the codes and see what the computer says is wrong…

    Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

    See http://www.troublecodes.net/Ford/
    OR
    See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
    OR
    See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

    Code 22 MAP (vacuum) or BARO signal out of range. The MAP or BARO sensor is pretty much the same sensor for both Mass Air & Speed Density cars. The main difference is where it is connected. Mass Air cars vent it to the atmosphere, while Speed Density cars connect it to the intake manifold vacuum. Its purpose is to help set a baseline for the air/fuel mixture and changes in barometric pressure. The MAP or BAP sensor puts out a square wave that changes frequency with variations in atmospheric pressure. The base is 154 HZ at 29.92" of mercury - dry sunny day at sea level, about 68-72 degrees. You need a oscilloscope or frequency meter to measure it.

    If it is defective, your air/fuel ratio will be off and the car’s performance & emissions will suffer
  18. T_5.0_N'works

    T_5.0_N'works New Member

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    CHECK YOUR GROUNDS! Make sure they are on good and have a clean contact.
  19. FiveO

    FiveO Founding Member

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    could be your TFI module. i know when mine went bad i had bogging like yours. or did the TFI not come till 89?
    then again you have msd, so i dunno. :shrug:
  20. SilverBullit

    SilverBullit Founding Member

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    I've heard of people checking and replacing the TFI module, what is it exactly and where is it located. Can it be checked. Thanks for all the help guys.

    Casey

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