Misfire bugging me

[spooner1129]

Ok guys I know there is a thread out there already for this but I feel mine is a little different. 2005 ford ranger 3.0 5speed 4wd. Had it parked for 2 weeks then fired it up took it for a drive, engine light came on ran the code came up cylender 6 misfire so I changed plugs wires and could pack cleared the code and it ran good for 30 miles till it started to mis at low rpms agian but never had the code come back. I have changed everything (plugs wires coil pack maf aic valve tps cleaned throttle body I had Evan changed the head and still have a misfire under 15k checked for vacume leaks and changed fuel filter still nothing. I'm pretty mechanical when it comes to engines but I need help

 

[Doofy]

The brand of spark plugs can be a source of mis-fires. I tried a set of E3's and immediately has mis-fires on 2 different cylinders. Threw them in the garbage and went back to Motorcraft. Problem solved!

 

[uksparky]

Could be low compression if it has problem under 1.5 rpm....pull each plug wire at idle until you find the bad cylinder...then compression check....if thats not your problem doing that...run engine at night look for any shorting at the ignition.....vacuum leak intake hose..
And not forgetting the injectors... touch them with something and listen them clicking...also test
fuel injectors with OHM meter, 11-18ohms is spec..

 

[spooner1129]

Well I replaced the plugs with motor craft plugs checked for breaks in the plug wires ran the truck at night looking for shorts and checked all the injectors with a meter and they all checked out good within spec like UKSPARKY said. Still misfiring but it did throw the engine light on agian and it came up cylender 1 misfire this time