2005 3.0 multiple cylinder miss fire at idle

[joshuakaesekamp]

I have a 2005 ford ranger 3.0 and I have codes for miss fire on startup, random/multiple cylinder miss fire. And then miss fire for cylinders 1 2 and 6 but that’s not consistent it will change somtimes which cylinders. It only misfires at idle it’s worse normally when it’s cold or just when it’s been sitting at idle for alittle bit and feels completely normal when driving it I’ve replaced all spark plugs tested the coil which the primary tested 1.4 1.4 and then .6 don’t know if the one being lower than the rest is an issue but it was inspec according to my Manual. And then the secondaries all tested 13.4k so I believe my spark is good. Fuel pressure is good at 65psi Ive replaced the fuel filter and all the fuel injectors have been replaced. I’ve done a compression test to all of them they were all the same besides cylinder 2 but it was only like 10psi difference don’t think it’s possible for the one cylinder to cause the rest to misfire like they are but I could be wrong. I’ve checked vacuum and im getting around 17 at idle. If anyone has any ideas on what it could be it would be much appreciated im kinda running out of ideas on what it could be or maybe I’ve missed somthing.

 

[franklin2]

A vacuum reading of 17 at idle seems low to me. Spray some brake cleaner around and see if you have a vacuum leak. The engine should speed up when you hit the leak.

 

[joshuakaesekamp]

I sprayed around didn’t seem find any spot that changed the engine I did around the intake and all the vacuum hoses. And they all looked good too no dry rotting or anything like that.

 

[pjtoledo]

cleaned the MAF sensor? they are delicate, be careful.

 

[joshuakaesekamp]

Yes I have cleaned the maf sensor sprayed some maf cleaner in it didn’t seem to make a difference

 

[Lefty]

Check for cracked spark plug wires or just replace them, especially if they are the originals.

 

[franklin2]

Yes, the wires can go bad when they get old, especially if they have been taken on and off a couple of times without being careful. They are nothing but string with graphite in it, they are very easy to break.

 

[joshuakaesekamp]

Just replaced all the wires and the coil while I was there. Still no difference

 

[stmitch]

Having the exact codes would be nice.
Truly random misfires indicate it's not an issue with a single cylinder or bank of cylinders, so we can probably eliminate stuff like a bad fuel injector, spark plug, etc.
Things that would impact all cylinders would be vacuum leaks, timing related sensor failure (crank position, cam synchro sensor, etc), or air supply related like a bad MAF. Considering what you've already replaced and tested, I'd probably look closely at the various sensors related to spark timing.

 

[joshuakaesekamp]

It ended up being a couple bad valves. So got the heads redone and it’s all fixed now. Thanks

 

[ptf18]

It ended up being a couple bad valves. So got the heads redone and it’s all fixed now. Thanks

Who did your head work? What was done?