Rough Idle and Burning Smell

[blacknight123]

Hi, I have a 1998 Mercury Mountaineer 5.0L. My check engine light came on and I took the car to autozone to have the codes read. Two codes came up P0340 and P0430. The P0340 was the cam shaft position sensor/synchronizer which I replaced. But the car still has a very rough idle when on park or drive and their is a bad exhaust smell that gets worse the longer the car is being drivin. I thought that I might be that Cat Converter but I do notice that when I start the car water comes out of the tailpipe( I assume thats good). I am going to change the spark plugs and ignition coils to see if that works. Any thoughts would be much appreciated thank you.

 

[Snowboi]

Erm' "car water", how much water would you guess comes out within a 30 minute period? Is water like pouring out of the exhaust, or just like a small drip, if its a drip, its fine, if water is pouring out for more than 5 minutes, then check your coolant level, you may have a bad head gasket if the coolant level goes down alot. The small could just be the water burning off, some water in the exhaust is completely normal, there's alot of ways water/water vapor get into the exhaust, while the water burns off, it will take some of the exhaust buildup with it, which can smell bad, but still its normal.

First, just change the plugs, check to see if there fouled up or burnt, no real reason to change the coil pack, because if there's no sign that there's a problem with it (mis-fire, or not firing on a cyl.) then there's really no reason to replace it, unless you would feel better about it being replaced.

Good luck.

 

[blacknight123]

Sorry for the confusion only a little water comes out like dripping, not a lot of water. I am still in the process of replacing the spark plugs but what I did notice on the fourth cylinder spark plug it was burnt and covered in oil. Thats probably bad but any thoughts? Also I was reading some other threads on this forum and they said that sometimes if you switch/replace the rear 02 sensor on bank 2 (drivers side) then that also might fix the rough idle and burning exhaust smell? Thanks in advance.

 

[Snowboi]

I don't know about that, personally, if it doesn't throw a code, I wouldn't worry about it. Have you ever heard of SeaFoam, its a cleaner that you put in both your gas tank and through a vacuum hose, it does good stuff, it may help the smell, it may stop the smell, but its worth a try. Also, what gas are you using (low, mid, or premium), different fuel grades can cause different smells, it could be just bad gas from the gas station.

 

[blacknight123]

No I haven't heard of SeaFoam but I will give it a try. You wouldn't know how to put it through vacuum hose would you?