My 4.0 V6 sounds like it's running fine upon start up, but after it warms up it sure seems as though it has a misfire or major hiccup. I replaced the coil pack, the wires, 6 spark plugs, cleaned the MAF sensor and listened to the injectors with a stethoscope. I changed the oil and added Engine Restore with the new oil. The engine starts up, no abnormal engine noise and all systems appear to be working until it warms up. The check engine light comes on and then starts flashing. I am at my whits end...any ideas?
The first time around, I got two banks running lean and one or two misfiring cylinders. I did all the above work and then reset the codes. When I started the truck, cold, it ran perfect until it warmed up and then it started skipping and running rough (put, put, put out the muffler). I took it to a garage who then took it to another garage and did not tell me the codes, except that they said two spark plugs were bad. I had all new spark plugs put in and it's still running rough. I'm at my whits end. I'll probably focus on the O2 sensors next.
my 99 ranger is doing the same thing.My mechanic has tries everything in the book but it still shows miss on #2 & #3 cylinders. He has tested compression,plugs and wires,smoke tested it,replaced coil.He said he's done just about all he knows to do. I hope somebody out there has some kind of solution for both of us.
