Well i recently bought my car and had it in for inspection, and it needed a weld done to the exaust, and now recently when i drive it it makes this terrible knocking grinding noise when i hold my foot steady at around 2k rpm's. as soon as i let off the gas, it stops. the car is an a4, and i havnt had time to get up under it to look, any one have any ideas? It sounds like its metal on metal, and makes me think. It seems to be coming from right under the center console/passenger side, so im thinking it has to do with the cat or maybe somehting with the transmission, any ideas?

 

Exaust hitting the bottom of the car? You have headers and a Y pipe?

 

No i do not have headers or a Y pipe. Just from the sound alone, it doesnt sound like it could be the exaust bouncing, also that wouldnt really explain why i can control it by keeping my foot steady at a certain rpm. Also, i forgot to mention, that it does this sometimes, not always but sometimes when the car gets a cold start and is just idling it makes this noise, but not as noticable.

 

check your cats. do you have any loss in power?

 

I don't really get on the car alot so nothing noticable. Im at work right now, but after work ill check the cat's, is their anything i should look for?

 

What is the oil pressure?

 

Oil pressure is fine, got off work late tonight so didnt bother with the cats cus its to dark.

 

Thats certainly a positive!

 

Try to shake the sxaust. When my Y pipe was knocking it didnt sound anything like a Y bang. Motor mounts? Also look for any rub marks on your exaust. Its crazy how just a littlr movement on your exaust will cause alot of noise.