Hey guys, just bought a 02 Ranger that had the transmission go out on it. I bought it for 1700 dollars. At the time, there was no CEL or rough idle that I noticed, but it couldnt be test drove. I towed it home, and had the transmission fixed. After picking up the truck, it threw a cylinder 4 misfire code and had a rough idle It throws the code when it has a long idle, such as a long light. It does not seem to throw the code when driving. The truck also bucks and stumbles right around 3k RPMS. I have replaced the spark plugs, the wires, the coil pack, the fuel filter, the injectors AND the Cam position syncro. It still has the same symptoms. When I pull the boot off cylinder 4, there is almost no change in how it runs. So cylinder 4 seems to be pretty much useless. I'm thinking that its a valve or headgasket issue. Going to run a compression test tomorrow. Any thoughts or advice?

 

Flipking,

Did you ever get to do a compression test? Do you have a spark tester?
If you have a spark tester, check firing on No. 4. If you don`t, go to H***** F******
and get one. They are cheap. Also, you can run a paperclip up into the boot at the plug or at the coil and jump a spark their to ground as well. My thought is that if the computer is telling one to fire it will be telling all to fire. Also, I have seen more than one bad plug in my time, straight out of the box. Did you put never seize or something like that on when you put the plugs in ? It helps complete the circuit between the plug and the block. Copper is best. Did you check the plugs again to make sure you didn`t accidentally bang the tip and close the gap. That will result in very low-voltage spark and may be too low to fire the gasoline off. I hope you got it fixed but if you didn`t get back on here. Maybe we can figure out something.

 

Also, and I know this sounds goofy but if you will get some ScotchBrite pad or the wife`s scratch pad and clean off all the little teeth on the crankshaft where it goes under the crankshaft sensor, it might help. There may be some magnetized metal shavings there that are interfering with the sensor. You can take the sensor off too and make sure it has no trash on it. Or it could be loose. Also, the antiknock sensor on the left side of the motor, you can make sure it`s connection is secure. It is down by the motor mount. If it is an RPM thing these two rascals might be giving you trouble.