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  • SN95 4.6L Mustang Tech

Car's missing, please set me in the right direction

  • Thread starter Thread starter bryan0
  • Start date Start date Jan 28, 2007

bryan0

New Member
Jun 9, 2005
175
0
0
Bethel, CT
Jan 28, 2007
#1
  • Jan 28, 2007
  • #1
Hi, I have a 99 GT with a mongoose vortech sq kit and the mph powerpipe. Lately, the car has been missing under load. If i were to put it in say 4th gear at 2500rpm and stomp on it, there would be a constant bububububububu almost like making your lips vibrate back and forth, that's the best way i can describe it.

I have the sct xcalibrator and decided to try and datalog it. I'm not to familiar with which paramaters to test. This is what i came up with:

Red = RPM
Pink = MPH
Yellow = Short Term Fuel Trim 1
Green = Short Term Fuel Trim 2



See how it drops off real quick right before the bottom says 119? That's where it was missing like a son of a gun. What could be the problem?

I'll try different paramaters and post a graph, let me know which ones would be useful. Note, I cleaned the maf to the best of my ability already, so I'm assuming this isn't the problem.
 

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blubullett

Member
Jun 22, 2006
535
6
18
Modesto, CA
Jan 28, 2007
#2
  • Jan 28, 2007
  • #2
Mine was missing and it turned out to be my coil packs. It would rev fine but if i put a load on it it would start missing at 4000 rpm.
 

bryan0

New Member
Jun 9, 2005
175
0
0
Bethel, CT
Jan 28, 2007
#3
  • Jan 28, 2007
  • #3
Hmmm... Thanks for the advice, I'll have to check into that. Anyone else?
 

GT_green_GT

New Member
Dec 31, 2005
118
0
0
Jan 28, 2007
#4
  • Jan 28, 2007
  • #4
If possible you need to cancel cylinders tell you figure out what cylinder it is. And check that coil out. It does sound like a spark problem. Narrowing it down to one cylinder helps. Now if its a random missfire on any cylinder you have a different problem.
 

bryan0

New Member
Jun 9, 2005
175
0
0
Bethel, CT
Jan 29, 2007
#5
  • Jan 29, 2007
  • #5
Well I replaced the spark plugs and everything seems okay now. They only had about 5,000 miles on them but they looked pretty blackened and one or two were even a little bent-looking. Thanks for your help guys
 
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