Hi Everyone,

Been noticing a "thump" sound coming from the exhaust when I start the car in the AM. Almost sounds like some sort of misfire but I am not knowledgeable enough to know for sure. This only happens when the engine is revving at the 1500 or so RPMs during the first 30-60 seconds after starting up. Once the engine settles in to the 700 RPMs everything seems just fine and she runs very good. The check engine light has not gone off so I am somewhat at a loss. Maybe this is normal but I just noticed it a few months ago and it seems like the "thump," for lack of better terms, is intensifying.

Any ideas or experience with this?

Thanks!

Corey

 

I would check for a loose exhaust due to failed or failing exhaust mounts.

 

Semi random ideas:

• Check the engine mounts. I believe they are filled with dyed liquid (purple, green?) that leaks out when they fail
• Check all the mounting points of the exhaust system.
• Maybe the catalytic converter material is coming loose inside the converter. Definitely gets worse over time as the ceramic breaks apart and eventually plugs up the exhaust. Not sure there is another option besides pulling the converter from the car and check it for loose internals (shake it).

Best of luck, keep us posted.

 

Hi Everyone,

Just wanted to provide an update. The other day the jag started running very rough. I checked the codes and P0302 threw. Managed to get the car home and I put a spare coil in the #2 cylinder and all is well. She runs great again. Strangely, I did not notice the thump this morning when I started it up. Do you guys think that the thump could have been a mild misfire while the engine was warming up as opposed to something exhaust related? I looked at the exhaust and under the car and everything seemed in good order but I am by no means an exhaust expert. Thinking that maybe the thump was a misfire all along.

Thanks!

Corey