Question about 2001 Ford Mustang

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Number 5 cylinder fouling out 3.8

The car started missing one day so I replaced the plugs and wires and it ran worse. When I pulled the old plugs out the seemed fine, when it ran worse with the new plugs I thought it was the coil pack so I changed it. Then the parts store said that I had the wrong type of plugs and when I took them out number 5 was fouled. Fast forward I replaced the plugs wires and coil twice, still numberr 5 fouls. The plug comes out black, not oil. I thought stuck injector, I stopped asking the autoparts people for advice. I took the injectors out preassure checked and cleaned them but none were stuck but I put them back in different locations anyway. Still number 5 fouls out imediatly. WHAT THE. Im think electrical now but dont know where to start.

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  • drewlinz Feb 15, 2009

    Ok, I did a compression test and all cylinders are at 120 lbs and then I took off the valve cover to check for broken springs and stuff and everything is in order. I put the car back together and disconnected the injector for number 5 and started the car and it ran smooth (no popping) but with the obviouse miss. Im thinking computer?



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It don't sound electrical to me sense you chg. all that, the plugs you put in are they a hotter plug? You don't by chance have a broken valve spring do ya, thats what it sounds like to me. Just sounds to me that its valve spring most likely exhaust valve.

Posted on Feb 14, 2009

  • ccn7 Feb 15, 2009

    This might not mean much, seeings i miss it on the valve spring, well i tride, seems like it would have kicked on the chk. engine light if a cyl. wasent fireing thru inlector, have you tried a test light on that electrical plug for #5 see if its bright or weak, just a thought.



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