4 Cyl Backfiring

Hey all,

New here. I have had my 4 cylinder 5 spd 09 Tacoma for 4 years now. I average about 10,000 miles a year. Recently I have been noticing a burning oil smell idling or on the highway. It seems the likely culprit is the valve cover gasket. However I have also been experiencing some pretty serious, yet random backfiring. It genuinely sounds like I have a jake brake when I let off the gas. It happens some days, and not other days. I just changed the oil and she hasn't lost any measurable amount yet. I have also swapped out the spark plugs, which seemed to look just fine, and actually the new plugs seem to make the backfiring more pronounced.

Any thoughts?

 

Have you checked for exhaust leaks?

 

Replace the valve cover but more importantly the spark plug tubes seals, immediately. Pop an ignition coil out and see if the tip is oily. Good luck.

 

Recently i had the flange at the Cat/muffler replaced due to a leak. I also has a new muffler installed after it developed a hole in the side.

 

Sounds like unburned fuel is making it into the exhaust. Do you have any trouble codes, check engine light or obvious misfires while driving?

 

Can such a severe problem as backfiring be present with NO code(s)? I can't think of anything that would cause backfiring that WOULDN'T also throw a code, but I'm DIY and not a pro.

 

no codes, its a clean dashboard
145,000 miles