misfire in 3

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Feb 3, 2008 | 07:05 PM

daxelson

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misfire in 3

I have a ford f150 with a 4.6l. code reader tells misfire in 1 and 3 replaced all plugs, went to misfire in 3. checked wire for 3, looks good has resistance, checked coil, testing to specs acording to my repair manual. what else can i check?

Feb 4, 2008 | 10:49 AM

KingRanchMan02

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From: Louisville, Kentucky

Welcome to FTE daxelson!

How many miles on the truck? Do you know if the spark plug wires are original equipment wires? What kind of spark plugs did you use? Good luck!

Feb 4, 2008 | 06:18 PM

daxelson

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I got about 1 yr/20000 mi on these plugs and wires, put new autolite xp iridium plugs in according to oriley parts guy is what book calls for. the old plug in number 3 had ceramic broken around eletrode but no other damage to it

Feb 4, 2008 | 09:13 PM

daxelson

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just did a visual spark check, saw arc from number 1 but not 3, fixed that, pulled 1 and 3 plugs, everything looked good, swaped fuel injectors 1 and 3, erased codes, took it for a drive got same p0303 code

Feb 4, 2008 | 10:19 PM

superdutymj

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From: La Crosse, Kansas

how much resistance did the #3 wire have?

Feb 5, 2008 | 09:39 AM

KingRanchMan02

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From: Louisville, Kentucky

Can you say "Replace the coil"?

Feb 9, 2008 | 09:58 AM

daxelson

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swaped coils and changed out the wire, pulled the plug and found no compression in the 3 cylinder, good compression in the others, thinking now bad valve. looked for antifreeze leak for cracked head or bad head gasket, nothing. will be pulling off valve cover next.