Misfire issues
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5th Wheeling
Joined: Jul 2024
Posts: 34
Likes: 1
Misfire issues
Alright, so I changed out my spark plugs and wires and it was running smooth for a couple days but all of a sudden it started idling rough like it had a misfire but all the plugs and wires are seated correctly. Anyone have any suggestions on what it could be or what I could have possible missed? The engine is a 4.6 V8 in a 97 F150
More Turbo
Joined: Sep 2017
Posts: 574
Likes: 146
Since you have no codes you will need to do some diagnostics.
-- check the vacuum hoses. maybe one got knocked loose when you were working on the plugs
-- Check the fuel pressure and fuel pressure regulator.
-- Do a vacuum gauge check on the engine. see if it tells you anything.
-- check the vacuum hoses. maybe one got knocked loose when you were working on the plugs
-- Check the fuel pressure and fuel pressure regulator.
-- Do a vacuum gauge check on the engine. see if it tells you anything.
Fleet Mechanic
Joined: Jul 2019
Posts: 1,317
Likes: 314
Fuel, spark, compression. What’s going sideways?
You won’t necessarily get a CEL for misfires unless they’re hard enough. But, a scanner with Mode 6 can check the counts on each cylinder for you.
You won’t necessarily get a CEL for misfires unless they’re hard enough. But, a scanner with Mode 6 can check the counts on each cylinder for you.
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Fleet Owner
Joined: Aug 2010
Posts: 21,254
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From: Reynoldsburg, Ohio
Is this engine pre-COP? I'm not familar with that year ingnttion system by if so was the rotor annd/or distributor cap checked/replaced?
This might be a defective new plug wire and/or spark plug itself----check the ignition system with an automotive oscilloscope. Sounds too familiar to an old-skool guy like me!
1
This might be a defective new plug wire and/or spark plug itself----check the ignition system with an automotive oscilloscope. Sounds too familiar to an old-skool guy like me!
1
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fejetmech
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Mar 19, 2003 09:22 AM