Bad smell from the exhaust pipe

[krijohn1012]

Hi, my 1998 s14 240sx has a bad smell of gas from the exhaust pipe. Anybody knows what went wrong?

Let me tell you what I have done so far.... The car failed the recent smog test, but I don't know what are the causes of the problem.... During that time, the really bad smell came out from the exhaust....

I tried to fix the problem myself by buying a code reader to check the emission problem. The problem seems to be the knock sensor that the code reader told me. I replaced the knock sensor then all of the code has gone. However, the bad smell is still there......,but it's not as bad as it used to be ( based on my personal opinion)....

Anybody helps me please......Do you think changing a Catalytic converter will help?

Or I need to change the oxygen sensor? but, the code reader didn't tell something wrong about the O2 sensors....which I believe that they 're working fine.....

[180fan]

your injectors could be the culprit. A bad cat will stink like rotten eggs, not like gas. But it's probably being eaten from the inside from the burning gas, so it might be in your best interest to replace it if you're having trouble passing emissions. I'd look first for a bad fpr or leaking injectors, off timing, or bad plugs. Actually yeah how do the plugs look?

[krijohn1012]

I have no ideas how does the plugs look....but I'll take a look at them. my car has 58K miles which almost the time that the plugs need to be replaced recommended by the manufacturer......

However, I looked at the injectors and they are still in a nice shape....If this bad smell problem caused by bad injectors....what do I need to do?

Can I just clean those injectors? ...I think that they'll cost me a lot....for a brand new set.

[180fan]

With a multimeter, check the resistance across the injectors. Cleaning them is also a good idea, try using Greased Lightning's fuel system cleaner or Elf fuel conditioner if you can find it locally. I've tried the redline stuff, and it doesn't seem to be quite as effective as the other two I've mentioned.

Pull the spark plugs and let us know how the tips of the plugs are.

[krijohn1012]

anybody else?

[SR20drftSX]

my cars plugs a lil bit oily around the threds of the plugs but the center themselves are burnt dark black looking... i let the car warm up a bit then revved it to 5000 and my friend said it smelled like rotten eggs...i guess that means i need a new cat.? where can i get one for cheap? also...how do you guys feel about Bardahls No Smoke and No Leak oil conditioner and the Restore Oil treatment? thanks

Garrett NY

[180fan]

Haven't used Bardahl's stuff, have used Restore and didn't think it was all that great. You could just have something as simple as worn valve seals. Rotten eggs at the exhaust = worn cat. Try heavythrottle for a new cat.

[krijohn1012]

Here is the updated information that I have from taking out the spark plugs.

The spark plugs are in a good ( Really good) condition...no oil leak .. at all.....I think the head gasket is still in a good condition.... However, I am going to get the spark plugs replaced anyway since it almost 60K which I don't know much about the record of this car from the previous owner.... and it is recommended for our 240s to have the spark plug replaced.....at 60K....

I still don't know what causes the bad smell from the exhaust muffler....but what I am going to do is that I am going to replace the catalytic converter....... Since I have the register the car in California, which has a very strict emission standard...... I bought the car from GA.....which the catalytic converter is not the same one as the one used in CA.......

In my point of view, in order to have the car passed CA smog... I need to change the cat to the one that meets the CA emission standard.....

I'll update more after I have the cat changed...