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Thread: Advice needed

  1. #1
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    Unhappy Advice needed

    Hi, wonder if any of you could offer some advice? Just come back from 250 mile trip, heavy traffic all the way to destination, return journey much better. Anyway, car running great, very smooth etc.. but when cruising at 80-90 mph feels like fuel starvation, pulling back and then surging, if you floor it ..... absoluty flat, just doesnt want to play at all, under about 3500 rpm everything is good. Had car re-mapped by trevor at Roush, fueling was fine, made good power etc. Just had fuel filter off and drained fuel, everything was clean. Just do not know where to look next, any ideas chaps?

  2. #2
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    Sounds suspiciously like a fuel delivery problem at higher rpm. It probably would also be a good idea to make sure the plugs are in good conditon. Was the re-map done on a dyno? Is the fuel pump performance adequate? Has the wiring upgrade been done?
    Joel

    '67 Lotus Elan S3 DHC (owned since 1970)
    '17 Ford Focus RS

  3. #3

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    Quote Originally Posted by SFM View Post
    Hi, wonder if any of you could offer some advice? Just come back from 250 mile trip, heavy traffic all the way to destination, return journey much better. Anyway, car running great, very smooth etc.. but when cruising at 80-90 mph feels like fuel starvation, pulling back and then surging, if you floor it ..... absoluty flat, just doesnt want to play at all, under about 3500 rpm everything is good. Had car re-mapped by trevor at Roush, fueling was fine, made good power etc. Just had fuel filter off and drained fuel, everything was clean. Just do not know where to look next, any ideas chaps?
    If all mechanicals are fine (meaning you have checked fuel pressure static, at idle, and loaded, no intake and exhaust leaks) you may want to check the MAP sensor and TPS as they are the primary load determining devices for the engine ECU. MAP sensors are very common to fail though if the TPS is malfunctioning and sending improper data to the ecu then you will have an ecu outputting commands at the wrong load site. Seth

  4. #4
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    Ok guys, checked everything that i could today........ still doing it.
    Booked in to Roush for tuesday, hopefully they will sort it.

  5. #5
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    It will be very interesting to hear about their diagnosis and fix!
    Joel

    '67 Lotus Elan S3 DHC (owned since 1970)
    '17 Ford Focus RS

  6. #6
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    Just to let you know the outcome, all sorted [I think!!]
    turns out that the coils were cutting out at high revs, due to there not being enough voltage, it appears that this was a problem on some of the earlier cars [although mine is an 04 year] Trevor adjusted the voltage through the ecu and all appears to be good, will know more after a good thrash!!

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