!!!Help!! Acceleration Problem!!

Discussion in 'SN95 4.6L Mustang Tech' started by SC'D_96_COBRA, Jan 3, 2009.

  1. I have a problem. My car has trouble getting into high RPM's. The car accelerates through the RPMS fine on first gear, but on second gear when it start getting close to 4000 rpms my car feels like all power is lost. I shift to third it accelerates fine until the higher RPMs and it repeats the same as second gear.

    Yesterday I kept the pedal stomped all the way to the ground to see if the RPMs would eventually raise and it did slightly but then it would get stuck again. It never let me get to red line. When I had my pedal to the ground i was looking through my rear view mirror and i saw a large fire ball come out. That scared me so I turned off the car and let it cruise to a stop.

    I drove my car back home a few miles and I didnt feel anything abnormal. As of today I have been driving my car and I dont feel anything weird in idle or when driving like a grandma. The problem is only at high RPMS. I noticed also that I can get to High RPM's but only with the throttle slowly being increased.

    Any ideas or suggestions would be really appreciated.
  2. Ignition system would be my first suspicion. The "large fire ball" is evidence that the fire isn't getting lit under those conditions -- high RPM, WOT -- and raw fuel is accumulating in the exhaust waiting to be lit.

    Plugs, wires, crank sensor, coils etc. Check it all.
  3. Are you sure the RPM's stopped rising? Because if the RPMs rise but you don't gain any speed it's the clutch that's going out. Otherwise I would agree with above and start with the spark plugs, wires, etc.
  4. start with replacing the fuel filter
  5. Then check plugs...
  6. Supercharged engines are really sensitive to older plugs. I would try that first. When they start getting older it will miss in the higher rpms.
  7. belt slip maybe ? watch the boost gauge and see if it flutters at all
  8. Thanks alot guys for all the ideas. I dont think my clutch is slipping because i belive the RPM's would surge all the way to red line with full throttle if it were.

    2002BLGT what other symptoms would a belt slip show??

    Tommorow the first thing im going to buy are new spark plugs and wires. I have NGK iridium spark plugs in my engine. Do you guys think this is OK or are there any other suggestions for my supercharged application?

    If anyone has anymore ideas please post your message it will be realy helpful.
  9. Check and replace fuel filter!
  10. Fuel filter - easier, less expensive and more likely the culprit.
  11. Thanks alot guys for all the Info. I changed the spark plugs today(technically yesterday) and that solved the problem. I change my spark plugs from NGK Iridium to NGK Tr6. I will not bad mouth the iridium plugs because i think they were gapped incorrecly. When i measured them they were gaped .05.

    I gapped the TR6 to 0.032 and that seemed to do the trick.
  12. i would still do the fuel filter though
  13. could be valve springs i knew a guy had the same problem at 3500 rpms, turned out he needed valve springs