Running Rough
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Joined: Jun 2004
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Running Rough
55 k miles on engine so it was time to replaced spark plugs in 4.6. Now engine is running rough. Took out all plugs and checked gaps, checked wires, fuel ejector connections, vacuum hoses. Cann't find anything wrong. Any ideas.
Thanks
Kevin
Thanks
Kevin
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Joined: May 2004
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From: B'ville, WV
I changed mine in my V6 and used Bosch plugs. It ran horrible afterwards. I changed them again, back to Motorcraft. I unplugged the battery to reset the computer. It ran much better with the Motorcraft back in it. I was talking to a guy at the local Advance Auto and he told me never to use Bosch in a "newer" Ford. He said they would burn up the COPS??? I'm sure someone with more knowledge and experience on here can verify if that is true or not.
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I did the same thing. Now have motorcraft plugs in. Some improvement but not much. Just checked vacuum and it is at 17". Is that too low or OK? What are COPS?
Last edited by kfnpemai; Jun 29, 2004 at 04:35 PM.
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Joined: Aug 2002
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From: BC, Canada
Hi Kevin and welcome to the forum 
The earlier 4.6's had spark plug wires, the later ones had COPs (Coil On Plug) which is a seperate coil sitting on top of each spark plug.
17" of vacuum does sound low. I would check all the vacuum hoses again. Did you replace the plug wires? Maybe got 2 backwards on the coil? PCV valve connected ok? At the back of the throttle body too?
The earlier 4.6's had spark plug wires, the later ones had COPs (Coil On Plug) which is a seperate coil sitting on top of each spark plug.
17" of vacuum does sound low. I would check all the vacuum hoses again. Did you replace the plug wires? Maybe got 2 backwards on the coil? PCV valve connected ok? At the back of the throttle body too?
