4.6L (1996-2004 Modular) Mustang Technical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within.

Misfiring...again...

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Old Jun 22, 2007 | 01:14 AM
  #1  
USMCSS's Avatar
USMCSS
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Default Misfiring...again...

My car seems to be slightly mis-firing for the 2nd time I've owned it and was doing it for the previous owner according to the receipts he passed on to me. Not sure which cylinder yet as I have not had ANY time to get to somebody with a computer to scan it.

#1 and #8 had both coils and plugs replaced at 43,050 miles.
#5 coil and plug was replaced at 52,102 miles.

I'm now at around 56K miles and the car is "skipping" just a little upon rapid acceleration and I'm not talking about when I floor it. Just high rpm's between shifting. According to the last service receipt for #5 "No other misfires are present at this time" What gives? Why am I going thru plugs and coil packs so much?

p.s. I know it's not the fuel filter as I just changed that about 500 miles ago.

My car: '99 Saleen S281 S/C, o/r x-pipes, shory headers, Borla/Saleen catbach and a few other bolt ons.
Old Jun 22, 2007 | 01:20 AM
  #2  
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metaldrummer
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Default RE: Misfiring...again...

I was having the same problem. It turned out that I had a bad coil pack and the cylinder wasn't firing. I had a noticeable stutter in acceleration until the coil and plug was replaced. It's a good thing to take care of soon so you don't end up hurting your motor.
Old Jun 22, 2007 | 01:28 AM
  #3  
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USMCSS
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Default RE: Misfiring...again...

I'm sure that's what it is, but why does this keep happening? Coil replacement isn't cheap.
Old Jun 22, 2007 | 01:30 AM
  #4  
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blackstallion666
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Default RE: Misfiring...again...

just replace all the plugs. sometimes water and moisture will get into the spark plug whole and cause the spark plugs to rust and corrode. and will cause a miss.
Old Jun 22, 2007 | 03:27 AM
  #5  
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LetThePoniesRunFree
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Default RE: Misfiring...again...

ORIGINAL: USMCSS

My car seems to be slightly mis-firing for the 2nd time I've owned it and was doing it for the previous owner according to the receipts he passed on to me. Not sure which cylinder yet as I have not had ANY time to get to somebody with a computer to scan it.

#1 and #8 had both coils and plugs replaced at 43,050 miles.
#5 coil and plug was replaced at 52,102 miles.

I'm now at around 56K miles and the car is "skipping" just a little upon rapid acceleration and I'm not talking about when I floor it. Just high rpm's between shifting. According to the last service receipt for #5 "No other misfires are present at this time" What gives? Why am I going thru plugs and coil packs so much?

p.s. I know it's not the fuel filter as I just changed that about 500 miles ago.

My car: '99 Saleen S281 S/C, o/r x-pipes, shory headers, Borla/Saleen catbach and a few other bolt ons.
If you have inherited a "problem" car, it's not a bad idea to invest in an OBD II scanner. You can pick one up for less than a factory coil pack. In layman's terms, you've got to know what your car is telling you before you start replacing parts. Once you have that information, it will be 1000 times easier to diagnose the problem.





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