I have a 1996 4Runner with a 3.4 V6 that has 284k miles. It has had quite a lot of work done to it by a trusted Toyota mechanic friend such as new valve cover gaskets,rear main and oil pan gasket. It does not leak or burn any oil and runs great until yesterday. As I was coming home from work I stopped at a light and noticed it was idling rough. It was dark so I drove it home and it smoothed out while I was driving but when I parked the rough Idle came back. I also noticed a lot of white smoke from the tailpipe At this point the engine was warm. Later that day when cold I started it again and the same thing. Rough idle,white smoke and water from tailpipe.Temp gauge is normal with no overheating. And then the check engine light came on. I have checked the oil and it looks fine. Coolant level was just a little low but not bad.. I do have an exhaust leak and have a hole in the muffler. It has these symptoms when cold or warm it seems.

Any help?

 

Maybe blown intake manifold gasket.

 

What was the code for the CEL?

 

Dont know the code yet. Gonna have it checked tomorrow at Autozone.

 

Also I forgot to add today when I started it at first it didnt turn over and clicked almost like bad battery or starter and then turned over. Both the battery and starter are new and have had no other starting issues until the smoke and rough idle began.

 

Maybe water in one, or more, cylinders.

Not quite enough to hydro-lock.

 

When the head cracked on my 5vz-fe it would hydro lock every now and then and do the same thing, and you could smell the antifreeze coming out of the tail pipe. I swapped the motor eventually.

 

White smoke means you're burning water (coolant), so it's got to be getting into the cylinders from somewhere. Check your spark plugs, could be head gasket and you would see one unusually clean plug in this case. If they're all clean, means probably not head gasket and the water is coming from upstream, maybe intake.