feels like fours cylinder idle rumble but unrelated to exhaust. WTF?

[shanker]

Every once in a while lately I'll stop at a light or sign and I'll get that rumble that old 4 cyls used to get in the same situation but when I rev the engine the rumble is still there and doesnt change pitch. It feels like its near the driveshaft maybe but I could just be on bad drugs or something.

Any ideas?

 

[CobraBob]

ttt

 

[05 Roush]

YEP!

Welcome to Spark Plug Syndrome. Sucks, but here's what you need to do. Pull each plug and remember their locations. If you have carbon scoring on any of the threads, you've got blowby. Swap non-blowby plugs with blowby ones.

Check for oddball plugs, ones that are cleaner than others. Replace these.

Put all the plugs back in and torque. Run up the gears. When the engine is hot, retorque the plugs.


The syndrome will also rear its ugly head as loss of top end boost (losing 1-2PSI WOT).