2004 F-150 5.4 L 3 V 180000 miles new timing job, new spark plugs, Removed cats because they were plugged up. Haven't replaced them yet. Truck never smoked before I remove the catalytic converter. The only thing I can come up with the may have started smoking was I had two spark plugs that cracked, and I drove it a few 100 miles like that. I am hoping that someone can point out a problem I am overlooking maybe in emissions or somewhere else. Thank you for any insight you may have on this issue.

 

What kind of smoke? Coolant? Oil? Water vapor?

 

Under what conditions does it smoke? Startup, warmup or at normal operating temperature.
Confirm you are talking about smoke in the exhaust.

 

• The cats may have been absorbing the smoke and that's why they stopped up and why you didn't see much until you removed them.

• If the smoke is black it may be due to the O2 sensors being confused and causing the PCM to make the mixture too rich.
• If the smoke is black or bluish, it might be due to incomplete combustion from those plugs not firing, causing unburned gas to wash the oil off the cylinder walls and the gas and oil mixture to get burned in the cats. Check for whether it smokes after replacing plugs. If so:
  • Check for oil or carbon fouling of the new plugs.
  • Check PCV valve
  • Check O2 sensor's reading with OBDII reader
  • Consider a stuck or leaking fuel injector
  • Consider a dirty MAF sensor
• If the smoke is white it's likely caused by a head gasket water leak.
  • Look for bubbles in the radiator or plastic reservoir.
  • Monitor coolant level in plastic reservoir.

 

I'm pretty certain it is oil it is a lingering smoke doesn't evaporate. But it's not blue. It does have a strong odor.

 

I'm pretty certain it is oil it is a lingering smoke doesn't evaporate. But it's not blue. It does have a strong odor. Thanks for the reply

 

Always smokes at startup if I let it set in idle for maybe 3 minutes it'll start smoking
Also almost always smokes after I've been running down the highway and stop and sit about the same time just is not real consistent.
I've never been able to see a trail of smoke while driving down the highway or a back Rd.
and yes it is smoke at the exhaust. Thank you for your reply

 

I will work on these things. I might say the engine is running quite well not a miss at all. Thank you for your reply.

 

So it's still smoking with the cats removed. And the smoke doesn't evaporate, is not blue and has a strong odor. So it must be oil, gas or oil and gas. If you rub the inside of the tailpipe, you should get black crud on your fingers.

I'd check the PCV valve first. If it rattles it's okay.

Then I'd pull those two new plugs and see if they have burned oil or carbon buildup.

Next steps depend on these results.

Incidentally, do you have an OBDII reader?

 

Rich mixture can cause this.
Often overlooked is dirty MAF, I would clean the MAF with MAF cleaner and see if that helps.
Codes?? You can have codes stored without a check engine light, Autozone or other will read for free, buy nothing, report back with codes.