Bent valve or valves?

There are several potential reasons why your Volkswagen Passat TD Estate might not be going over 3000rpm. Some possibilities include:

A problem with the engine: There could be an issue with the engine itself that is causing it to lose power or not rev up past 3000rpm. This could be due to a problem with the fuel delivery system, such as a clogged fuel filter or a faulty fuel pump. The ignition system could also be the cause, such as a malfunctioning ignition coil or spark plug. Another potential issue could be a problem with the engine's internal components, such as damaged valves or a worn out timing belt.

A faulty sensor: There are various sensors in your car that help the engine control system monitor and regulate various functions. If one of these sensors is not working properly, it could cause the engine to lose power or not rev up past a certain point. Possible culprits include the mass air flow sensor, the throttle position sensor, or the camshaft position sensor.

A restriction in the exhaust system: If there is a blockage or restriction in the exhaust system, it could limit the engine's ability to rev up past a certain point. This could be caused by a damaged exhaust manifold, a collapsed exhaust pipe, or a clogged catalytic converter.

A problem with the transmission: If there is an issue with the transmission, it could cause the engine to lose power or not rev up past a certain point. Possible problems include a worn out clutch, a faulty transmission mount, or a damaged transmission linkage.

To determine the cause of the problem, it will be necessary to have the car inspected by a qualified mechanic. They will be able to diagnose the issue using diagnostic tools and recommend the appropriate repair. If the problem is due to a faulty sensor or component, it will need to be replaced. If the issue is a more serious mechanical problem, it may require more extensive repair work.

If your standing still in park it wont rev past 3000 rpm as its got a limiter on it And only revs past 3000 rpm in drive on the move.

You didn't mention what sort of car you have.
You can try disconnecting the electrical lead on the MAP sensor. Then give the car a test drive.

A faulty MAP can cause high emissions, erratic running and high fuel consumption.

You can also try cleaning the EGR - the exhaust gas recycler valve.

It's strange that you have no fault codes. There is no check engine light illuminated?

A major vacuum leak could the problem. Anything restricting the intake flow, a dirty throttle body or stuck EGR may cause similar problems. Possibly a clogged catalytic converter or a muffler baffle that has come loose clogging the exhaust. Last on the list is improper valve timing, a stuck or burned valve or other major engine problem like a hole burned in a piston. A compression test may help pinpoint the problem.

If you're talking 4000 rpm, in neutral you'll cause engine damage! 2000 RPM is the max safe limit. Power loss is usually due to a restricted fuel filter. Does it smoke when running? (air filter), Try some Isopropyl alcohol deicer or fuel injector cleaner to ensure there's no water in the system. you haven't given enough info to diagnose the problem, i.e. drivability, history, and symtoms. BobB

IF YOU SEE CHECK ENGINE LIGHT FLASHING LOOK FOR TURBOCHARGER WASTEGATE REGULATOR VALVE FAULT OR MAP SENSOR FAULT.THAT COULD BE YOUR PROBLEM.IF NO CHECK ENGINE LIGHT FLASHING YOU COULD HAVE A RESTRICTED EXHAUST SYSTEM BAD TURBOCHARGER, RESTRICTED FUEL FILTER.ALL THOSE THINGS WILL CAUSE POWER LOST.

i am having the smae problem with my vw polo tdi apart from its like my turbo cuts out completly and the car will not rev over 3000 at all. there is know lights on in the dash but if its dry weather the car is fine. not to handy when u live in scotland HAHA

check for electrical short in the power supply for cpu

sounds like something was set up wrong.timing belt ...cam/crank sensor/ or work on mechanicals not clean..valves/piston damage...or....alot of junk went through motor when this occurred and your catalytic converter is clogged