Ok, some of you might remember that I installed a Mac Off road H pipe last week, and ever since then I can feel and hear a noise coming from the drivers side, on the floor. It sounds as though someone is underneath knocking on my floor board with knuckles, best way I can describe it. The vibration even travels through the gas and clutch pedal. It only happens while lightly accelerating, both when I'm letting the clutch out, or it's already all the way out. It's also not regular. Sometimes it happens, sometimes not. My first thought was clutch, but it's fine, just like before. My second though it the H hitting the floorboards while the engine torques a little, but this doesn't make sense since it doesn't happen while accelerating hard, only lightly. Did something come loose, because it happened on the first drive 5 minutes after the H pipe install. Has anybody else experienced something similar? What should I look for? Thanks a ton for any help.

 

Backfiring?
Just a guess

 

my car did the same thing check to see the clearences of your headers/manifols and see if ANY of the pipng is near the firewall, when you accelerate the engine flexes a little it might push one of the pipes into the bottom of your floor board that is what the noise was on my car, my header was hitting the firewall i pused the piping backwards a bit it whent away

 

Does youre pipes have all the proper hangers installed, Check to see if youre tranny mount is tight or could be worn out, Thats my guess.

 

e40..I'm thinking on the same line I bet those motor mount are wore

 

loosenut: That's what I think it is too. Something vibrating against the firewall, either an O2 sensor, or a portion of the pipe. When it's jacked up, there's about a 1/4" clearance there. Maybe when it get back on the ground, the clearance is even less.

e40water: That's also a good suggestion. I was thinking about checking that this weekend when I get it off the ground.

vfast: Kind of doubt it's the motor mounts. It's an '01 that's never driven hard. Also too much of a coincidence that it started making the noise immediately after the H pipe install.

Thanks for everyones tips and advice. If it might be something else, let me know. Thanks