intermittent misfire

[John Ratajczak]

Looking for ideas I have an intermittent misfire on my 01 4x4 ST. I replaced the plugs and wires last spring and this developed late summer. It is only under heavy load. I thought it was the coil so I replaced it today it isn't as noticable but it is still there. What else may be causing this. Thank you in advance for any help.



P.S. I also replaced the O2 sensors today (the origonal sensors had 137,000 miles on them) I used the Bosch sensors, drivers side worked fine but the passenger side wires were about 3" short. I ended up splicing the connector from the stock sensor to the new sensor to reach the connector. Just a heads up.

 

[EddieS'04]

Not imposible for a new plug or wire to go bad. I have had it happen on other cars. If you are geting CEL. The code will tell you which cylinder.

 

[Michael Cacioppo]

jrat454, If I read your post correctly the wires and plugs were replaced BEFORE the misfire happened. You may have a developed a bad plug or wire. You say that a new coil helped but did not alleviate the problem. I would assume that one of your wires is arcing to ground intermittently. You may have moved that wire slightly away from the ground when you changed out your coil. Checkout your wire routing to see if any wire is touching metal. I would assume you have a bad wire.

 

[John Ratajczak]

Thank You I guess I never had a new wire or plug go bad so it never crossed my mind. I will have my buddy bring his scan tool over today and see if it shows wat wire is bad.

 

[scott degroot]

Fords are very picky when it comes to spark plug wires, I only recommend using the oem wires, they cost more than the Autolites or whatever other garbage the parts store is selling but they work and you don't have these issues.

 

[Todd Z]

The common cracked elbow can cause a misfire a couple of days before it throws the CEL light....



If you have a Job 2 motor ( Oil fill on the passenger side) Check that out..



Todd Z

 

[EddieS'04]

The only wires I will buy from a parts house are. High quality name brand low resistance spiral cores. Parts house brand OEMs suck. Todd Z, sells a qaulity set of wires.

 

[John Ratajczak]

Scanner showed misfire on cylinder#5 so we put the origonal wire back on and will test drive it tomarrow (snowing and blowing today, a 4' drift is covering about 20' of my driveway will have to get out my '48 Ford 8n to clear it if the wind ever lets up)