Engine Performance problem
2003 Nissan Altima 4 cyl Front Wheel Drive Automatic 85000 miles
My car resently started missing and the check engine light came on. I was checking around the car while it was running and noticed that the tail pipe was omiting a heavy gas smell. Is this from the Spark plugs needing to be changed or something else.
Your catalytic converter is making that distinctive smell due to the misfire condition. Too much unburned fuel is being burned in the converter, i.E, the misfire you hear and feel. Operating your car in this condition not only will waste fuel, (we all know how expensive that is) but will cause your converter to overheat. Continued operation under these conditions is not advised because (1) converter will be damaged internally if allowed to continue, and (2), it is possible to set your car on fire!
You must first determine the cause of your misfire. The simplest way to do that is to use a computer code reader. It will provide what are called " trouble codes" specifically about the operating conditions of your engine. You can go to a parts store and have this checked for free in most cases. Buying a code reader while there is another possibility.
Once you have a trouble code downloaded from your on board computer, you can begin your diagnosis and repair. There may be more than one, though. Each code monitors the performance of a specific part and when the operating condition goes outside of the " normal" range for that part or that part stops working, it is recorded in your computer. So it is possible to have more than one code recorded, since some parts or conditions may or may not be related to each other. For example, worn spark plugs are not monitored as an operating condition but a misfire is. A bad or faulty cooling temperature sensor is monitored, but not all the systems it will affect if it stops working as it should are. It may or may not be a part of your misfire condition. It may be a separate condition not related to your problem.
A visual inspection of your ignition system is required. Check the condition of your plugs, wires, cap and rotor. If any are noticeably worn out, replace. If these parts are good or new, then do not replace.
I assume you have a 4-cylinder. If you have recently done tune-up work involving replacement of any of the above parts, you must be sure that the routing of your plug wires is correct. The firing order for your engine is 1-3-4-2. What that means is cylinder number one fires first, followed by cylinder number 3, etc. You may have the right wire in the right spark plug hole, but a common error, even for an experienced mechanic, is to put the other end at the distributor cap in the wrong spot.
There will be no trouble code for this condition!
Take your distributor cap off and have someone else crank your engine. Note which way the rotor turns. It should be either clockwise or counter clockwise. I believe for your car it is clockwise. Next, find the spot for cylinder number one on the cap. Sometimes, but not always, the tower hole is marked as #1. Double check the routing for cylinder number one is correct. If not, put it in the correct tower hole. Now that you know which way the rotor turns, go to cylinder number three and check that routing. Cylinder number three is the third spark plug hole from the fan or drive belt. Fix that as needed, and then check number four and then two. Reinstall the cap. It is not necessary to crank the engine any longer than necessary to determine the rotor rotation. Just bumping the starter a little bit is enough. The rotation of your rotor will determine which cylinder will fire next.
Hope this helps.
If this is not what is wrong, then use the information you get from the code reader to fix and repair. If repairing does not work, then something else is wrong, such as a dropped or burned valve, cylinder head gasket blown, bad or low compression in one cylinder. In other words, your engine is not in good sound mechanical condition.