random cyl#4 missfire

started about 8mo ago. when it started the check engine light would come on, I would reset it and it would come back on about a moth later. I changed the spark plugs and the cyl#4 coil. now the problem has steadily gotten worse to the point where the check engine light will come back on within a few days of resetting it. my engine is not consuming coolant and there is nothing entering the engine oil. truck is a 2005 4.0 with 181,000mi. does anyone know whats going on? I don't know how to tell if my camshaft position sensor or crankshaft position sensor are faulty.

 

Bump for you

 

Whats the code?

 

Check this guy's website -

http://troubleshootmyvehicle.com/toyota/1.8/corolla-misfire-case-study-1

I dealt with an isolated misfire on my wife's high mileage 2004 Corolla using these guides, and was able to fix it. The root cause was a faulty Denso sparkplug which had the porcellan core detached from the nut causing it to essentially float freely with a variable gap size..which then caused damage to the ignition coil. If you smell fuel while the engine is running while misfiring, it could be because the spark isn't igniting the fuel.

Read the codes first and determine whether its either cylinder specific or a random misfire to indicate where to start. Check compression (comparing across all cylinders), then check spark, then check the fuel injector. If those are all ok, then the issue is elsewhere.

 

^This.

 

I will have to go to autozone and have the code red to get exact code #

 

A clogged fuel injector will cause misfires too.