raspy low rpm wot exhaust note, less backpressure/power. any suggestions?
 

Hey everyone. The car is a 05 tl 6 spd. Recently smogged it. There is no cel. Meticulously maintained. Oil changed every 3k. Has new timing belt, water pump, spark plugs, clutch, air filter. The car ran better than ever for a couple of months. Now it has this issue where there is some power loss but more noticeable is the exhaust note. The car sounds like an old pickup truck from the 60's. I thought there was an exhaust leak but I checked and it's fine. What could be causing this noise and loss of backpressure? Thanks.

Any codes ????
 

Check intake manifold for build up .. if ELM327 can't pinpoint. Might of lost a resonator cell. Is odd. But I've seen it happen.. more info can give better advice. Retrain ecm. Will set at 100miles unless is not on default.. 3 cells intake ,exhaust and fuel ..

No check engine lights. ELM327 does show EVAP.

I take that back. ELM327 is saying all sensors passed along with the EVAP.

The loudest part of the exhaust seems to be directly underneath the engine. Sounds like there's a hole in the exhaust but there isn't any. Thanks

Your system is regulated by computers excluding the mechanical....etc
 

Reset the hidden codes that enable over 30mph. Also if backfired back side eng plug the PVC valve back in. Head pressure will unseat. If it is pure mechanical grinding rubbing..Do not run...1 computer can trip a process that will draw over the harness. I've tracked crazy codes that registered the the only 1 ecm s/n ...send photo mp4 link to view so a better plan can be worked and blueprinted..your throttle body will advance retard air fuel to make it's own proper setting..I read 75%of this forums knowledge and you have some amazing friends here that will show your the same issue and walk-through or revisions that will better suit the individual situation...the more info you provide the quality of precise information can be sent to you. Salt , vacuum leaks, bad grounds, faulty sensors all easy fixes....find or code your car. No codes ok. Some are hidden in special areas iacv has a pre set rpm. If mass and egr sys work in sync... any work done recently wrongly flipped gasket can make chaos.. if looks and sounds ok proceed to start your computer will auto compensate with bump check. Pull plugs check vacuum rattle the PVC. See if it clicks I blew mine out on 103 octane had similar results but air suction gave it away as car went off.

Thanks for the info although it is confusing. How do I reset the hidden codes?

Ok check computers for pid and dtc codes on software you should check 18 to 24 the srs reset will dump stored codes this is a paper clip hard reset. Reset can be done for faults in computer but cleared by different ways be cleared in software and module reset. By clearing them they reset defaults . Need a basis to point to a area. intake and exhaust pressure check will tell you info Internal External any odd noise , have you seafoam ever. Alt and battery low volt can effect . What's charging amps Volt ¿¿ .defult Is 750 + and - 100 after start warm . Thermostat opening check laser temp gauge. How do fluids look , baking soda and vinegar do great for grounds , clean off hood air vent pop hood up. Unhook air to throttle body Leave filter in box tip up only after unhooking the j pipe. Have you ran an injection cleaner before . Have you checked the intake ports for buildup. Check all fuse proper volt. Any lights on. ?? Shift up your steering column this will stress the ignition connector. Harness cleaner works great make sure No Batt power and discharge before use .

Is the gas pedal key in the on position method the way to reset it for a manual? Or do the manual transmission tl's require a different way to reset?

You probably have an exhaust leak. That would explain the noise. Best get it checked out by a mechanic

FYI I've had a few myself, the noise is a dead giveaway

UPDATE

I am now getting a check engine light. Code P0137 - secondary o2 sensor circuit low voltage

well, Have you gotten under the car and looked and felt for air pressure??????

you said there's no holes, perhaps the leak is so small YOU cant see it... You will need to feel for air pressure BLASTING through a pipe or flange.
this means the car needs to be on.

Yes, i checked. There seems to be a leak coming from my exhaust manifold gasket

Update
I'm told my rear exhaust manifold gasket is shot and my car isn't throwing any codes. Can such a small leak rob that much power is what I was thinking. But two different muffler shops shared the same opinion. Anyway, is the car safe to drive or can I damage valves?

It was the rear exhaust manifold gasket. But I found out I have a bad timing belt tensioner too. It was the other part of the noise. More noticeable at idle, especially cold. Thanks guys.