hello! I just bought a 2004 Ford Ranger. It threw a code for a misfire in cylinder 6 when i got home. did a compression test and it was close to the same on all cylinders. I changed all the cables and plugs, they all had regular wear and didnt look fouled or anything like that. So it ran good for about 50 km and then the CEL came on again. This time reading misfires in cylinders 6 and 4. losing my mind and my shirt with this one. gonna try the coil pack next. when i clear the code and let the engine cool down it runs really good for a bit until it throws the code again. any advice out there for my issue?

 

Hey try looking more towards maybe evap, I have recently bought a 2002 and had the same problem, i do not know whether your truck is equipped with an egr or not, as mine doesn't have it. My problem was the purge valve, located under the ABS module between the battery and brake master cylinder. Yours may be in a different place, but this is where mine was located.

 

im not sure if it does. from what i've read on here they say the 3.0 dont have it but the 4.0 and 2.3's do.

 

Is there a way that i can diagnose the Purge Valve?

 

Purge valve issue should set another code as its part of EVAP system, an emissions system so heavily monitored

The 2004-2006 Ranger 3.0l's were known to throw misfire codes because of exhaust valve seat issues, it can come and go, as the seats shifted
You did a compression test when engine was cold, and got ???, 3.0l should be 165-170psi, 9.3:1 ratio

I would do one after engine is warmed up, yes its a pain, lol
Remove all spark plugs first
Then test each cylinder writing down results

So at least take compression issue off the table or find out it is the problem, so no wasting money and time on non-fixes