Hi, my n249 located on top of gearbox has failed. While running vcds output tests one of n249 does not make clicking sound. I have no vacuum leak as tested by smoke machine.
Is there no other way to bypass n249 valve as it's stuck open.

What else you would recommend to replace while engine out?

Thank you

 

Stuck open would equate to loss of power, this is the case? Bypassing still requires engine out. Bypass would be hard on the turbos. Hard de-acceleration after wide open throttle creates spurious boost pressure which needs to be vented to the atmosphere.

Suggested aspects to consider with engine out. Replacement of Lambda sensors. Evaluate condition of flexible wire loom covering for disintegration. PCV pipes are often brittle, time to fix. Serpentine belt replacement, consider replacement of idler pulleys and tensioner. Check the starter, load and resistance test. Motor mount condition evaluation. Front-end bushings that are old, easier to fix now. Replace plastic vacuum lines with metal. Do not use radiator worm clamps use oiniker, or fuel injector clamps. There are probably other opinions out there.
Regards,
Keep us posted.

PS. Exhaust temperature sensors bank 1 and bank 2, worth evaluating changing out.

 

 

Typically the various sensors that control boost should throw codes if defective.

Obviously, changing parts without verification is risky, taking the engine out two times is not fun. Before removing the engine might I suggest more analysis. I doubt it's a massive vacume leak, there are aggressive codes for this situation.

When a diverter valve diaphragm fails this can cause the turbos to not pressurize. However, the chances of both diverter valve diaphragms failing at the same time is unusual with no codes.

Look on the Audi and Volkswagen forums regarding lack of turbo boost. The technology and concepts are similar.