So, I have my 2001 3.0 Ford Ranger for about 6 years and about 40k added miles (160k currently). I've done the regular maintenance on it (Oil changes, filters, sensors occasionally) to upkeep the vehicle. I have had a running issue for the last few weeks where the car has a rough idle. It used to be very rough going in reverse backing out of the driveway and as I started to drive around, the roughness would stop. MPG would drop drastically over the last few months from 280 total to 260 250 and now average about 240. Check engine light would turn on, and then turn off for a few days. Now more recently my car is essentially always rough and even feels like driving over little bumps sometimes. Like the engine is lagging. Constant check engine and Flashing about 20 times. Getting a Cylinder 2 misfire so assuming it had to do with ignition, I went through the basic chain of spark plugs, injectors, Coil Pack. etc. Nothing solved it. I did notice that cylinder 1 and 2's spark plug had burned up and smelled bad when pulling them out. It did smooth out a little bit but overall still the same. When revving the engine, the car is very rough right in the 1500rpm range just in park. I did the MAF sensor test by unplugging it to see if the engine would shut off, it did not. The car also did not run smooth after unplugging either. None of the wires or anything look like a problem. Not sure if it is a mechanical problem or some sensor that is throwing the whole car off. Please help. I commute 2 times a week 50+ miles.

 

Welcome to the forum

I assume you have a 3.0l OHV Vulcan engine in the 2001 Australian Ranger?

Next step will be a Compression test
All spark plugs removed for the test
Cold engine
Expected is 150+ psi
But the point of a compression test is the average psi on that day with that pressure gauge and that cranking speed(battery)
Rule of thumb is 10%
If average is 150psi then 15 is 10%
Then a cylinder with 130psi is more than 10% away from the average, so will misfire or partial fire, doesn't add the same power as the other cylinders so rough running


All gasoline engines with valves will get burnt exhaust valves, the 3.0l Vulcan was a little more prone to this
Once an exhaust valve starts to leak it just gets worse over time and miles
And this lowers compress in that cylinder