Mis-downshift redline

Discussion in 'Fiesta ST Maintenance' started by Atlas4gr, Dec 18, 2013.

  1. Atlas4gr

    Atlas4gr New Member

    Hi guys,

    New to this site, I was messing around giving my friend a test ride in my ST and went from 3rd to 2nd instead of 4th, engine went into the redline for a second or two. There was no crazy traction stall or jerking motion, just wondering if there is any potential for damage I might have caused. Should I take it in to the dealer for a diagnostic? Any info would be greaty appreciated
     
  2. Register or Sign in

    Advertisement Sponsor

     
  3. Cligedy

    Cligedy Active Member

    I wouldn't sweat it. The big danger with over revving is typically valve float, and then the potential for the piston to hit the valves. If you can't tell any difference, then probably no issues.

    Sent from my XT907 using Tapatalk
     
  4. stuntdoogie

    stuntdoogie Active Member

    Happened to me once but instead I shifted from 4th to 3rd when trying to shift to 5th. I was paranoid that whole day listening to my engine constantly for any weird noises which it already had...you know that annoying ticking sound from the head lol
     
  5. rweidman

    rweidman New Member

    That is what rev limiters are for. Bounced off of it once and message came up about fuel shut off, Never noticed any further effects.
     
  6. RodMoe

    RodMoe Well-Known Member

    msg came up on MFT screen ? i never saw one the only time i bumped it though i was looking at the tach not the MFT screen...
     
  7. D1JL

    D1JL Well-Known Member

    If the check engine light didn't come on then I don't think you have much to worry about.
    However you may have shortened the life of the clutch by a small amount.

    Dave
     
  8. mamiata1

    mamiata1 Active Member

    I had a friend once that while going down the back straight at Waterford Hills in a Porsche 914 6 hit second instead of fourth gear and that was crunch time. But that was a pancake (boxer) 6 cylinder and he went way over the rev limit. Some valves and springs had to be replaced. Still, I pretty much agree with others above that in a modern car with more fail safes like fuel cutoff chances are you're OK. And also consider that if you tune your engine with the Cobb unit one of the first things it does is raise the rev limit. So there's some "fudge" factor in there.
     
  9. eRic

    eRic Active Member

    I almost did a 2-1 "upshift" in my 2011 Fiesta at Waterford Hills on the way up to hilltop. Thankfully I realized that I selected 1st instead of 3rd before completely releasing the clutch. The fuel shutoff won't save you when the speed of the tires/wheels/transaxle mechanically force the engine speed to 7000 rpm. of course this happened when I had a passenger and my onboard video camera recording the session. D'oh!
     
    reddog99 likes this.
  10. wash

    wash Active Member

    Relax, the 1.6 is an under square engine with small valves and DOHC, the mass of the valve and tappet is very low and turbo motors usually have mild ramp rates and heavy springs (so the boost pressure doesn't blow the intake valve off the seat).

    I would be very surprised if the engine couldn't stand short duration over-rev to 8,000 or 9,000 rpm several times.

    Also realize that the rev limit is so low because the turbo runs out of air flow, not because bad things start to happen at 6,600 rpm.
     
  11. D1JL

    D1JL Well-Known Member

    Once apon a time I downshifted form forth to second in my track car at about 140 MPH going into turn one at Willow Springs.
    I immediately started uncontrolled donuts and took every bit of pad off the clutch.
    However did NOT hurt the engine.

    Dave
     
  12. nummypuppies

    nummypuppies New Member

    My wife went into 1st instead of 3rd once while accelerating. Barely hit the limiter and no harm done. These cars are pretty forgiving it seems. In my old 5 speed eclipse, if you hit the wrong gear in the wrong speed and rev range, you were having a bad time.
     
  13. audiphile

    audiphile Member

    Folks, there is a name for it, it's called MONEY SHIFT. There is nothing modern fuel shut off can do about it. If you downshift and let off the clutch, you're forcing the wheels and engine to interlock. If that happens to be at engine speeds higher than redline, then you might cause damage that no modern tech can prevent..
     
    reddog99 likes this.
  14. Sekred

    Sekred Active Member

    Relax, whats the worst that could happen??

     
  15. audiphile

    audiphile Member

  16. wash

    wash Active Member

    Have you ever wondered why a Formula 1 engine can run at 20,000 rpm for several races but a NASCAR engine will grenade at 11,000 rpm?

    Its because 5.8l v8s use big heavy pistons with a fairly long stroke and 2.4l v-10s use tiny pistons with really short stroke.

    Compared with another Ford product, the Coyote 5.0 which is good for 8,000 rpm with reasonable durability, the EcoBoost 1.6 has smaller pistons and a shorter stroke. It has other advantages also like only one rod per crank throw and lighter rods too.

    I don't know how high the 1.6 can rev before it pops but I'm certain its far above its artificially low "redline" fuel shutoff rpm.
     
  17. audiphile

    audiphile Member

    I totally agree with you. I bet our engine can turn much faster without any damage than the fuel cut off.. I'm just making a point about what money shift is and how it works.. On the other hand, if you're WOT at redline in 3rd and shift to 2nd by accident, then fully release the clutch, you'll bend things...
     
  18. D1JL

    D1JL Well-Known Member

    As I stated above I was lucky to only take out the clutch.
    As the attached 5.8 L would have been expensive.

    [​IMG]


    Dave
     
    Sekred and Firesail like this.
  19. Sekred

    Sekred Active Member

    Want someone to build you a engine for your fiesta, these are the guys to see.

     
    Last edited: Dec 23, 2013
  20. Steve@Tasca

    Steve@Tasca Fiesta ST Network Sponsor

    Others have mentioned it but no one quoted you so just for the record. A rev limiter can't prevent an over rev caused by a missed shift, downshift from 6th to 2nd at high speed and you will very likely damage engine, clutch, trans or axle parts.
     
    Smokin and reddog99 like this.
  21. Steve@Tasca

    Steve@Tasca Fiesta ST Network Sponsor

    Don't forget the pneumatic valve actuation in the F1 engine and the use of MUCH stronger materials used in the entire assembly.

    -Steve
     

Share This Page