98 cobra, doesnt seem as fast.

Discussion in 'SVT Tech Forum' started by stang dreamer, Jan 4, 2009.


  1. stang dreamer

    stang dreamer New Member

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    i have had my nearly stock 98 cobra for a year and 4 months now, and have been driving it for a little over a year. i didnt really give it much abuse until around 5 months ago, i dont abuse the car that often now, but when i do it doesnt feel as quick to respond as it used to. at the top end of the rev range it launches you back, but doesnt feel as fast as i want it to lower down. the only thing that the car has is a 93 octane tune, as i have a diablo predator. i havent modified the tune.

    now i also have a C&L intake and K&N filter combo as well which i used to use. when i originally got the intake and filter, it constantly stalled itself and seemed to drop power low down, so i stuck the higher octane tune and continued to use the more expensive fuel. it didnt make much difference so i removed the filter.

    when i start the car in the morning it seems to splutter slightly. the second it fires up, the revs will shoot up to 1500rpm, splutters, drops back down to around 800 then pulls back up to 1200 while it warms itself up. i changed the spark plugs just incase but it made little to no difference.

    my question is, does it sound like my coilpacks/ ignition leads need replacing? the car has done 85,000 miles now but was stored for a while before i bought it. every other sn95 i have driven seems to have a smoother idle, starts with the turn of a key, revs fine and generally seems smoother, no matter what the milage it has covered, i have changed the spark plugs and fuel filter, cleaned the MAF and IAC valve around 3000 miles ago, changed oil and oil filter around 1000 miles ago. i am using the stock filter i got with the car and havent changed the battery.

    ill get a video posted of the startup shortly, you will see what i mean. anyone have any tips or hints?
     
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  2. btmhwb

    btmhwb New Member

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    I am no expert myself, but have you had it dynoed and made sure the a/f was okay using that canned tune? I just know that 03/04 cobra motors are real sensitive to tuning and everyone told me not to use a canned tune. Hopefully someone else will chime in and help.:shrug:
     
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  3. stang dreamer

    stang dreamer New Member

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    i never thought of that. i changed back to the standard octane tune not too long ago and it felt like it lacked some get-up-and-go and it also kept throwing up the check engine light, but no codes :shrug:

    every time i had driven it for a while and came to a complete stop, the check engine came on. had to change it back to the 93 octane tune supplied with the predator tuner, since then its been fine but as i said, doesnt seem as fast as it used to. i have been meaning to get it dyno'd to check power. not many dyno tuners over the pond though.
     
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  4. btmhwb

    btmhwb New Member

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    didn't realize you were in the UK!!! If you can't find a reputable tuner in your area you should get a custom remote tune for your car and get the a/f checked on a dyno when you get a chance. I think it would still benefit your car by doing so. Amazon racing and RWTD are good tuners you could use. Hope this helps!!
     
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  5. soon2bblown

    soon2bblown Founding Member

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    4.30 gears would solve all your probs..
     
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  6. stang dreamer

    stang dreamer New Member

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    the only tuner in my area is a place called awesome GTI, they charge around £350 ($600 est) on the rollers for A/F ratio tweaking and power gains... looks like i will have to do some saving :)

    i was looking into 4.10s for a while, but doesnt traction then become an issue? i would have thought with the gains in accelleration the tyres would be easier to spin. also, what gains would i see hooking the tyres and doing a 0-60 sprint? i can get it to 60 in around 6.5 seconds on stock width tyres, around 6 post burnout at the moment. with a bit of practice, what could i expect shaven off the time using 4.10s?
     
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  7. soon2bblown

    soon2bblown Founding Member

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    Alot!! These cars need alot of gear to get them in their sweet spot. 4.10 are ok, but 4.30 are an awesome all around gear for the 4valve.

    If you put a set of 4.10's or 4.30's in the rear, you could almost shave a half a second off of those 0-60 times. Don't worry about traction. You might have to play around a little to figure out how to launch the car but it's all worth it!!!:nice:
     
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  8. soon2bblown

    soon2bblown Founding Member

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    One thing to try


    Any tune you put into the car with that tuner mabey try returning it to stock. There is really no need or benefit with a tuner and a stock 98 cobra IMO.
     
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  9. stang dreamer

    stang dreamer New Member

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    i returned it to stock, as per my above post. all it did was flatten the feeling of torque in the car, and keep throwing up the check engine light without codes. every time i came to a complete stop the engine threw up the light, but never with any codes. weird.

    the one thing i will say though, is that i have to be careful with 4.30 gears in the uk, just because of the fuel economy situation. its not too bad as it is, but i dont want to make it any worse than it has to be. probably wont make much difference at 50mph, but i would imagine revs significantly higher at 70mph. top speed is also sacrificed by a good margin isnt it.
     
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  10. soon2bblown

    soon2bblown Founding Member

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    Sorry I did kinda skim through your OP.

    I actually got better mileage around town after the gears. At 70 mph you wont be to happy with the 4.30's, the 4.10's would be decent. You kinda seem to want a little of everything which I understand, but you kinda have to pay for speed one way or another. If you do alot of highway driving mabey stray away from gears...

    Top speed on an otherwise stock car would actually increase with the 4.10's.
    The only reason why is you car doesn't have the power stock to reach the full potential of your 3.27 gears.

    Steeper rear end gears actually help you reach more of your powerband. It sounds weird but it's true...
     
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  11. stang dreamer

    stang dreamer New Member

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    i never thought of the strains the original gears put on the motor. i have heard a lot about the 4.10's increasing wear and tear in the motor because of the extra speed the revs are at. surely if the engine is under much less pressure to begin with it would be less of a strain? its like riding a bike slightly uphill. its more tiring in a lower gear because its a lot harder to pedal uphill, even though you are pedalling slower. with a higher gear its a lot easier even though your legs are going faster.

    i would like a fast mustang that is usable in the UK, this car is my daily driver and we get heavy rain even through the summer months so i want to make sure i have enough traction to actually drive it :)
     
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  12. soon2bblown

    soon2bblown Founding Member

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    What you are reffering to is torque multiplication (sp?). Thats exactly what gears do.

    For a daily driver if you just drive your car normally, you wont even know theres 4.10 gears in that car. Once you get on it you'll feel it though. Or if you cruise at a high speed, say 80 Mph. I really think 4.10's would work perfect for you..:nice:
     
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  13. stang dreamer

    stang dreamer New Member

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    great. they should make my car feel like brand new then i hope. :) while im at it, i think i will have to replace the clutch pack and rebuild the rear axle as it only spins one wheel also :rlaugh:
     
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