1999 Ford Ranger MisFire

[j.apps]

When im driving my 1999 ford ranger down the road it has a horrible mis. Does anyone know where i should start? It have the 4.0 v6.

 

[almostclueless]

Basics.

1. Fluid levels
2. Change sparkplugs, replacing with autolite double platinums
3. Inspect wires and replace if necessary
4. Ford dealership diagnostic

 

[rangerbert]

The tune-up should also incude changing fuel filter, and pcv valve. the pcv valve often gets overlooked. If you still have the problems after the tune-up then get the diagnostic tests done.

 

[Dajamax]

If it's truely a miss-fire, follow the advice previously given.

But another item to check is the Mass Airflow Sensor. If it gets gunked up, your engine performance can change virtually overnight and give you the sensation that it is miss-firing. Usually you can just clean it with electronic spray cleaner or white vineger. It happened to my 4.0L ... the engine shook so bad I thought I had a broken engine mount, or bent drive shaft and/or failed u-joints. After I cleaned the MAF, it ran alot better, but still not perfect. Wound up buying a new MAF, and now the engine runs smooth as silk.