I was driving home today and my car sounds completely differently. I have been running a mpx catless dp n catback exhaust for about 2 months so I have grown to know the sound of the car inside n out. The car sounds like a boxer engine now almost like a vr6 vw or a sti, it sounds very deep. It concerned me so much that I went home jacked the car up checked all connections on my exhaust. I had a hunch that it could have been my spark plugs making it sound odd. Then I took my spark plugs out, did a compression test ( 120psi / 150psi across the board) n even put all new spark plugs in...car still runs 15psi of boost n pulls very strong but the exhaust note is polar opposite of what it sounded like yesterday. Any ideas? Should I put my stock dp in n take it to the dealer n have them check it?

 

pull spark plugs, check compression again...the fact that one cyl u mentioned is 120 is not good

chances are #4 piston ring land let go.

Build time my friend, you will soon have a strong engine with performance parts once the disassemble and repair

 

Forgot to mention. 120psi on the first puff then climbs right to 150 it did that on all 4, all 4 are running a solid 150 psi but the inital crank of the motor brings it to 120

 

150 is low

 

I don't think there's anything wrong with it.

 

I believe it is perfectly fine for an LNF.

 

I would pull the valve cover and take a look ..... people have had broken cam followers and not known it till they pulled the cover.

 

Does it always do this or only every once in a while? Another member and myself have had this happen when cruising at highway speeds in 5th gear the car will start to sound just like your describing a Subaru Boxer engine for a few minutes and then everything will return to normal. I'm not sure what this is but it confuses me.

 

^^^^^^Cam phasers, change the oil sooner.

 

Idling sounds stock, but throughout all the gears it sounds like a boxer engine now, very choppy sounding

Last oil change was 6,500km ago I do one every 10,000km

 

My car sounded very "Boxer" sounding when the Front O2 went bad. Cheap thing to try, its $60.

 

Did it fix it? Do you think it's plauseable cause of my catless dp

 

I was referring to the sound that comes and goes. If a cam phaser hangs up, it'll sound weird.

The LNF was designed to be a 0w-30 engine but the cam phasers would wierd out when the oil started to break down. A GM engineer posted this on another forum. Oil changes are fairly cheap to try.

I change mine at 50-55% oil life. Usually around 5k miles.

 

On my car that was the fix. If you have the ability to look at the trims it's easy to tell when it's bad.