My 2.8 4m40 engine turbo charge has a whistle noise when i accelerate

Could be injector timing issues. Too far retarded will give poor response and a knocking sound, a bit like the old Commer Knocker engines.

Leaking Vaccum Line or the intake system has a leak between the air filter housing(air box) and the engine's throttle body, that's usually the culprit!

any part driven by the drive belt can do this

turbo whistle is common as it comes from the tips of the compressor wheel passing through the sound barrier and the turbulence occurs. IN the older trucks you would the turbo whistle as the engine reached full RPM just before a gear change. In smaller engine it is not do noticeable as there is an excess of air pressure that keeps the compressor wheel at a lower rpm and the pressure is dumped out. Turbo compressors reach revolutions in excess of 120.000 rpm under full load If it has just started to make the noise then check the intercooler system for leaks--loose clamps--- splits - Have the turbo compressor checked for damaged fins from the ingress of fine dirt from a bad air filter---check the air filter is not blocked as the turbo speed may result from running in a partial vacuum ( no load on the compressor wheel)

If the engine is a diesel that is equipped with a turbocharger, I would look for a pressured air leak at any and all hose connections. Especially when the engine is running at accelerated speeds which cause the turbo to operate as a charger.
Check any and all belts for slipping, Alternator, P/S,etc.,

I don't know if this is the right place.
But I have a 98 Pajero 4m40. It starts and idles nicely, but upon acceleration, engine sounds terrible, almost like a non turbo L200 engine, even with the intercooler connected and turbo whistling. Please help.

Cleaning you air filter , fuel filter and water separator must be bleeding it might have a water in it.

If it a turbo model (petrol or diesel) there may be a loose or damaged hose to or from the turbo or intercooler, preventing charge air entering the engine. to have a quick check (this may or may not work, but it's worth a go) open the bonnet/hood with the engine running and listen for any blowing, sucking or whistling noises when the engine is revved. also, if you know anyone with an ODB2 diagnostic unit, they would be able to plug it in (socket under dash) and tell you more accurately what the problem is.
Hope this helps.

I took my car to Keller's Auto Repair in Gettysburg PA, He specializes in Chryslers. I have 04 Cruiser with 2.4 Turbo that had the same whistle noise, and check engine light on. He found code P0301. The noise was caused by the #1 Cylinder injector O ring. Check them out on facebook. They will help you.

http://www.facebook.com/#!/pages/Kellers-Auto-Repair/158207620880499

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