Exhaust Tone During Cold Start
 

I noticed that the exhaust tone (oem) is louder during the first 10 seconds during the cold starts and it toned down as the rpm drop a bit. However, I couldn't duplicate the same exhaust tone when I rev the engine up after it warned up.

This is the cat-converters warming up - once they flash-off, it alters the exhaust note. HFC are worse because they take longer to flash-off (is the difference between 400, 200 and 100 cell cats)

i wish my car sounded like that all the time. It's beautiful. Anyone know a way to do that?

yes buy an aftermarket exhaust lol

i don't think it's really the cats warming up aside from just the warm up process. i don't have cats but my engine idles high for those 10 seconds or whatever at 1200 rpm then it idles at 1k to warm up fully then its normal idle is 600 i believe.

Me too.

I suppose a "tuner" could put the cams on a larger overlap to create a "lope" during idle. Ford did this for the TrackKey calibration on'12 &'13 BOSS 302.

pretty sure the VVEL would not like that and override it on its own.

:ugh2:Or you can buy a damn exhaust smh

see my above post lol beat you to it :bowrofl:

Exhaust whore you are :rolleyes:

As said above, VVEL wouldn't allow it.

yes i most certainly am......speaking of that.


OP, go check out Fast Intentions if you want to take care of that exhaust sound issue. Tony and the guys will get you squared away with the perfect exhaust to match your needs 100%.

tell them i sent you :tiphat:

Do the cam phasers operate independently? Are they operated by the ECM/PCM/ECU?

It is apparent that the oem exhaust can produce nice sound, but just not quite sure how/why during the first 5 to 10 seconds on a cold start up.

However, I do know that it sounds pretty nice at high rpm.

I would argue that it has anything to do with the cats that the tone changes approximately 10 seconds after a cold start up.The rpm does not change either much if any in the first minute or longer for me, but the tone does go from a harsh raspy note to a softer note within that 10 seconds,like there is an exhaust valve in the system somewhere closing.I wonder if the ECU is changing the variable valve timing once the cold start has been sucessively established?

That's an interesting thought. The exhaust volume should go up with the engine rpm, but the raspy tone just can't be duplicated by reving the engine. However, it may sound similarly during higher rpm (5k+) driving.

you people hurt my head sometimes with this non sense.

its the car warming up so it revs at about 1200 for 10 seconds then drops to 1000 then 650 ish once its warm and the ECU has gone through its starting/warming protocols.

now for the sound change that has baffled all of you is due to the metal of the exhaust being cold. once the metal heats up a bit is when it drops off.

also the engine oil temp dictates some of that as well. not the oil itself but it's an indicator of the operation of the vehicle

trust me i have straight pipes. so I hear every change that the Z's engine and functions go through. cold starts in mine are fuckin MEAN lol after it drops off though its a nice V8 like rumble. once the metal heats up the tone changes. then again once the car is up to full operating temps the exhaust note changes and gets smoother and better sounding then as well.

you're all welcome :tiphat:

^^^ Yep

Some of the ideas, theories and posts on this forum sometimes are a little...:icon14:

Well it s nice to know you are reading the posts Whether they make sense or not.This is my first Performance car without a muscle V8 and its the first stock exhaust I ever heard that changes tone so quickly after a cold start up.