Hi everyone,

I have a '04 Coupe 6MT and it's always had a slight "pulse" while sitting at idle. At first I thought it was my engine but when I parked it in my garage, I noticed that the sound was coming from the exhaust. Also, my exhaust has more soot inside the tips than other Gs I've seen.

Now my first thought was that spark plugs need to be changed (which they did) so I changed them. At the same time, I also installed a 5/6 MD Spacer and reset the ECU. Well my car seemed to idle great when I first changed plugs and installed the spacer but now after about 2 weeks later, the exhaust noise is back and worse than before...

I've been reading and it seems like there's some unburnt gasoline getting through to the exhaust? Also maybe my car is running rich? My car is completely stock other than the Spacer.

Any help is much appreciated. Thanks. BTW, the car has 54k miles on it.

 

Any mods to the exhaust? Are you still running cats?

A definite suggestion is to get a can of CRC MAF Sensor Cleaner and follow the directions. That often will smooth out a rough idle.

 

Zero mods on the exhaust. I can give that a shot but I don't feel a roughness in my idle. It idles as ~650. But I'll try anything at this point. Thanks for the suggestion.

 

Check the engine speed while idle... do you see it drop suddenly with the exhaust noise? It's possible one or more of your plugs isn't firing at the right time (or at all).