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Fuel Cut Issue?

Discussion in 'Engine/Tuning' started by Rossim22, Feb 4, 2012.

  1. Rossim22

    Rossim22 New Member Established Member

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    I've been researching the issue but keep finding people with a delay at the top of their rpms. The issue I'm having happens during wot runs. Say a 2nd gear roll, slowly accelerate until wot and the car will pull hard as ever if i'm not spinning. Then i release throttle shift to 3rd and pound the throttle again. The car immediately falls on it's face, no acceleration no deceleration, everything feels silent like it's suffocated. I've had my tuner in the car when I did it (happens 85% of the time) and he thought it might be a torque limiter designed to save the stock driveline. We reconfig'd the limiter and the problem persists.

    Mods are posi port 2.76/4lb with 60# injectors, kb bap, dual gt pumps. I bought a modified fpdm and were having issues so we went back to stock. Later turns out that just a fuse popped so the modified is in my garage and stock istalled. I will be going to dual fpdms in the future

    Any ideas?
     
    Last edited: Feb 5, 2012
  2. CUINMYREARVIEW

    CUINMYREARVIEW New Member Established Member

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    really dumb ? what is the fpdm an where is it and where is the fuse located how did u test it thanks mike
     
  3. Rossim22

    Rossim22 New Member Established Member

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    bump
     
  4. Rossim22

    Rossim22 New Member Established Member

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    bump still need some help
     
  5. Black306

    Black306 Active Member Established Member

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    Sounds like a classic case of a PPRV hesitation. Do you still have the PPRV installed? Try data logging fuel pump duty cycle, fuel pressure drop, load, and rpm and post the results.
     
  6. Black306

    Black306 Active Member Established Member

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    Fuel Pump Driver Module. It is located behind the trunk liner on the drivers side. Checking for power (pin 9 with the key in the run position) and ECU codes are all you can really do to check an FPDM without specialized equipment. The fuse is located in the engine bay fuse panel. I don't recall the location, but it is a 20A mini fuse.
     
  7. Rossim22

    Rossim22 New Member Established Member

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    How if there's no hesitation? It pulls through the entire rpm range, then when i shift and smash the pedal, i get nothing. Silence. Like the car wants to accelerate but somethings not letting it. No hesitation, complete motionless with the rpms. And no codes are thrown. Tuner thinks it might be a torque based limiter cutting fuel after a spike in boost following the shift
     
  8. Black306

    Black306 Active Member Established Member

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    Last edited: Feb 6, 2012
  9. Rossim22

    Rossim22 New Member Established Member

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    Ahhh I see. I was getting results for people with hesitation at the higher rpms but this sounds like exactly what I have. Why would I have to get a new tuner? What in the tune is the problem and maybe I could tell him..?
     
  10. Black306

    Black306 Active Member Established Member

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    I won't go into too much detail, cause that alone could start its own thread. Ford did a poor job of implementing their returnless fuel system. Cause of that, the fuel tables need to be spot on. IMO, GT pumps are among the easier pumps to tune cause Ford provides the tables you can start with...from the GT. Of course each car is different and need tweaking, but there is a good starting point. Also, Ford has had the returnless system in Mustangs for over 12 years and this hesitation issue is far from new. Either your tuner is incapable or ill-informed about how to resolve the issue. That's why I say if you have the PPRV hesitation, find a new tuner capable of dealing with the intricacies of Ford's returnless fuel system. Personally, I wouldn't want anyone tuning my car that doesn't know what he is doing.
     
  11. Rossim22

    Rossim22 New Member Established Member

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    i understand what you mean, but after going to a renown Ford tuner, my driveability wasnt that great, performance was alright and I felt like he was just going through the motions of what he did on everyone's car... because all he sees is fords. This guy isn't as specialized but has tons of experience, great work, close by, and excellent customer service. This is the only issue we've had so I'm not going to cut him loose yet. I'm making 525whp on my eaton before spray, so is this hesitation unavoidable on the returnless at my power levels? Or just go with dual fpdm/pprv delete?
     
  12. Black306

    Black306 Active Member Established Member

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    In most cases, the hesitation can be tuned out. I wouldn't suggest going straight to a PPRV delete. I opted for a PPRV delete via a Fore hat mainly cause of the restriction, not the hesitation. My tuner was able to get rid of my hesitation before doing the hat.

    A dual FPDM conversion will do nothing for the hesitation.
     
  13. toomanytoys

    toomanytoys Active Member Established Member

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    My car is doing the exact same thing as yours and I dont have the amount of mods that you do. Im going to try and see if it can be tuned out with a PPRV delete being my next step.
     

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