2006. when I accelerate, why does it make a loud fluttering noise like exhaust blowing at manifold?

Can be many things. Check the cv joints first- will make sharp clicking noise especially when turning. Wheel bearing but it will be all the time and noise will increase with speed. Control arm bushes - shudder and noise when accelerating or when driving on road with an slight incline (up hill). If nothing obvious found take the car to an suspension specialist for evaluation and quote.

no 4-3 or 3-2 downshift
uncontrolled downshifts outside range of kickdown switch
poor acceleration from stopped position
parking pawl will not engage
selector lever does not engage in r or p
engine will not start in p or n position
smoke in exhaust (fluid loss)
fluid loss between torque converter & primary pump
howling noise when changing gears (under full load)
howling noise which increases as engine rpm increases
1st gear & reverse too loud
3rd gear too loud
rattling noise at 1500 rpm in all positions except r
light grinding noise in p & n positions
rolling noises when driving in reverse
vacuum control circuit
Vacuum Control Valve (E300D & S350D)
Vacuum Amplifier (E300D & S350D)

wheel bearings

sounds like your fan clutch may be failing, remove the drive belt and manually spin all the pulleys by have listen for noise and feel for looseness in the bearings

what oil did you use before . what brand and weigth .

Remember, what is heard as turbocharger noise may not be caused by a noisy turbocharger. Before replacing a turbocharger perform the following diagnosis.
A. If a loud whine or whistle is heard during acceleration and increases or decreases with rpm and load. This condition is most often the result of a loose clamp/hose at the turbocharger compressor outlet, charge air cooler inlet, outlet or at the intake manifold.

1. With the engine running at idle and the transmission in Park or Neutral with the parking brake set, feel for boost air escaping at each connection between the turbocharger compressor outlet and intake manifold. For limited access areas, spray soapy water on those connectors and look for bubbles.

2. Check the exhaust manifold and exhaust system for leaks.

I hope this helped.

Thank you,
Norse

Spark plug blow out?

see if te noise is there when stationary. if so hold the revs around 1500 to 2000 rpm if it rattles around that, then it is the heat sheild on the down pipe section thats broken free.

hi what type of noise is it is it an exhaust blow or a metal vibrasion if its a blow it will be a manifold gasket [either to the exhaust to manifold or manifold to head] possible crack in manifold if its a metal vibrasion it will be the manifold tin cover burned through where it bolts on