I've pulled off the 2 wires off the big sensor ontop of the thermostat housing. Went for a drive and noticed loud exhaust sound when in low revs and something which sounds like a butterfly closing in the exhaust and can also hear a whining/whistle.
I'm not sure what has caused the sound but I've never experienced that noise before pulling off the wires, its if there was a switch turned on and suddenly it sounds like there's no firewall its that loud and the noise turns off after a few seconds. It sounds like if there was a hole in the exhaust its that loud.
But when on motorway or powering through a gear both noises stop then return when low revs.
Do I need to put back the sensor, is this the cold starter in the downpipe and high revs pushing it open? its friggen annoying i've never heard those sounds on my car before ever.
engine is a 4jb1-t manual 1991
I was also wondering if the early 4jb1-t engine has a different downpipe as mine goes straight down infront of oil filter or is that normal?
Seems to be a lot of room for a larger downpipe on my engine?