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03 Gt Down On Horsepower

  • Thread starter Thread starter cray2602
  • Start date Start date Jul 31, 2016
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cray2602

New Member
Jul 31, 2016
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Jul 31, 2016
#1
  • Jul 31, 2016
  • #1
Bought an 03 GT 4.6L automatic that just feels sluggish to me. 0-60 time checks about 9 seconds. Should be closer to 6 or 7 from what i here. Need some help figuring out whats needing attention.
Heres what ive done so far.

Had a bad miss when i bought it, replaced plugs and runs fine now. Engine idles perfect and runs nice and smooth except when sitting in the car and increasing RPM the car vibrates pretty good. Steering wheel shakes in your hands. No funny engine noises. Wasnt able to get my compression gauge to screw into the heads for some reason so i ran a vacuum test and everything checked perfect. Pulls 20 at idle holding perfectly stable needle. Snap test drops to around 0, up to 25 and settles back to 20. Slowly increasing RPM checks ok, vacuum slowly rises a little, no exhaust restrictions aparently. Have an OBDII scanner and cant see anything that looks out of whack. O2 sensors are working right. MAF sensor is changing voltage as RPM increases so i assume its working correctly. No CEL light and no codes.

Any ideas where to look next? Kind of stumped.
 
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cray2602

New Member
Jul 31, 2016
6
0
1
Jul 31, 2016
#2
  • Jul 31, 2016
  • #2
Also replaced fuel filter and fuel pressure reads 40psi according to my scanner. Getting 19mpg the last two fill ups and i dont baby it.
 
Last edited: Jul 31, 2016
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