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2002 4.6 rough idle

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Old 03-22-2011, 07:13 PM   #1
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Default 2002 4.6 rough idle

My 02 4.6 has a rough idle it feels like a diesel what could it be it has a new tune up n the codes read cyl 1 so I replaced the coil and still rough idle but now no codes any ideas?
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Old 03-22-2011, 11:22 PM   #2
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My 02 4.6 has a rough idle it feels like a diesel what could it be it has a new tune up n the codes read cyl 1 so I replaced the coil and still rough idle but now no codes any ideas?
Did you clear the error codes from the ECM after the repair was made?
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Old 03-22-2011, 11:38 PM   #3
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Check the gap on the plug.
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Old 03-24-2011, 08:17 PM   #4
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Anyone?
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Old 03-24-2011, 08:59 PM   #5
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Is it a rough idle or a misfire. They're very different. Does it clear up when you hit the gas? Check the connectors to the injector and coil, the tabs on the coil connector like to break and come loose, I just wire tie them tight. Can you do a compression test, if so compare it with a good cylinder. If you cleared the code it won't come back until it sees the problem in more than one drive cycle and misfires have to be seen a certain percentage of total rotations. If it's just rough idle it could be a vacuum leak, IAC, MAF or another sensor left unplugged.
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Old 03-24-2011, 09:03 PM   #6
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Is it a rough idle or a misfire. They're very different. Does it clear up when you hit the gas? Check the connectors to the injector and coil, the tabs on the coil connector like to break and come loose, I just wire tie them tight. Can you do a compression test, if so compare it with a good cylinder. If you cleared the code it won't come back until it sees the problem in more than one drive cycle and misfires have to be seen a certain percentage of total rotations. If it's just rough idle it could be a vacuum leak, IAC, MAF or another sensor left unplugged.
It's a skip and rough idle what vacuum lines do I check and the IAC N MAF have been cleaned, what's the compression supposed to be at? And it said #1 cyl so I changed that coil... I'm lost need help or things to start checking thanks in advance..
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Old 03-24-2011, 09:10 PM   #7
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Unless you have a compression tester you'll need a shop to do it. It's a tool with a gauge that screws in where the spark plug goes and shows the compression of the cylinder. Like I said just look over the connectors and follow all the vacuum lines to make sure there's none that came off or broke. How long has it been since air/fuel filters?
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Old 03-24-2011, 09:11 PM   #8
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Compression should be in the 105-165 range. Vacuum lines, check them all and the base of the throttle body.
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Old 03-24-2011, 09:36 PM   #9
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Compression should be in the 105-165 range. Vacuum lines, check them all and the base of the throttle body.
Ok what ones are the vacuum lines god I sound dumb
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Old 03-24-2011, 09:39 PM   #10
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Quote:
Originally Posted by Austin97
Unless you have a compression tester you'll need a shop to do it. It's a tool with a gauge that screws in where the spark plug goes and shows the compression of the cylinder. Like I said just look over the connectors and follow all the vacuum lines to make sure there's none that came off or broke. How long has it been since air/fuel filters?
I don't have one but my buddys father has on that I can prob barrow and I think my grandfather who owns a garage has one.. And I know what it is and what it dose I used one on my snowmobile it has brand new air filter and I'm not sure bout fuel filters because I just bought the truck a few weeks ago and the guy was a lying caniving SOB.. the only thing he was truthful about was that the #1 cyl was skipping
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