Jetta wagon with BEW no power

Hi guys. I've been gone for a while but now that I have a diesel again I'm back.
I picked up a 2006 Jetta wagon. Fixed a bunch of stuff and got it running real nice. I have a Malone stage 2 on it now for a couple months and love it.
So a couple days ago I start the car and it have no power. It's not totally lifeless but it's lacking a good 100 hp. I've checked and test a bunch of things and can't figure this one out. I have a new maf which reads 450 at idle and goes to 900 when WOT. The vnt actuator moves when I rev the engine and so does the intake runner flap. Egr has been deleted. I have no codes. The requested boost at WOT only goes up to 1700 mBar and the actual get up to it. It's like it's in limp mode but it isn't or I'd get a code. I can't find and vacuum leaks or hear any boost leaks. I'm convinced to ECU is just not asking for more boost. What could be causing this? I have a vag com but only the trial version so I can only see up to measuring block 25. Please help.

Update....
If I turn my car off and back on I have full boost, but only for a couple seconds. So it is going into limp mode. Still no codes though..

It should have stored a code. If it does it several times it might light up the CEL.
Could be clogged air, loose piping, bad signals and on and on. Doesn't the vagcom check for stored codes?

The top hose is prone to being popped off on those engines, check the upper hose. Could be a bunch of things.

Hose is new.

What should the MAF read at idle?

Maf normally won't throw them into a full on limp mode, especially if you're able to get 900+ readings from it, but if it's not a bosch MAF return it and get an OEM one. Does the car go right into limp mode when you fire it up and start driving? or only once in boost?

I'd start with boost leaks, if your requested and actual differ by too much the car will go into limp mode, limp mode won't throw codes and is reset by restarting the car.

It's a Bosch MAF. I did some more testing today and found the internal resistance of the N75 is 1.5 ohms. Which is way below spec. It goes into limp mode after about 3 seconds of starting the car. I measured the resistance of the egr solenoid and got around 35 ohms. I'm going to replace the N75 tomorrow and test again. Does anyone know what the MAF should read at idle? I'm at 450 but I think it should be in the mid 200s.

Ok I replaced the N75 and still goes into limp more right away after starting. I re tested the old N75 and now I get 16 ohms, weird.

Have you measured the vacuum going to the turbo actuator?
I have about 18 inches at idle, it drops lower when I take off.

I haven't. What's the spec? I'll check it tomorrow.

TDISport said:

I haven't. What's the spec? I'll check it tomorrow.

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Don't know the spec but mine is what I posted.
I'm thinking you might not have enough vacuum.
If no or much lower vacuum you have something to start with.
You would need a vacuum pump to test if the actuator can hold vacuum and if it starts the arm moving at about 3 inches and is full on at 18 inches (or so).
You can also see if the arm moves smoothly or jerks as it goes.
Testing first is cheaper then guessing at what part to try next.
Harbor Freight has a vacuum brake bleeder for $20.00 that seems to have a similar vacuum pump to the one I paid about $40.00 for.

I have a mighty vac and I'll check it tomorrow. I was watching the actuator move when I reved the engine. But I'll check it properly with the gauge.

I didn't drive the car for a week and drove 300 kms today with full boost no problems. Just as I got home it went into limp mode. I restarted the car and it went into limp mode right away. So weird!!

You need to find someone with VCDS to do a full scan (yes even if the MIL isn't on) and to do some live graphing while driving.

scurvy said:

You need to find someone with VCDS to do a full scan (yes even if the MIL isn't on) and to do some live graphing while driving.

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This. Until you do that, you are wasting time.

A couple common spots on the BEW:

Brake booster tube leaks (loss of vacuum source, so VNT cannot work)

Vacuum hose to VNT rubs so thin it pinches itself shut as it snakes down alongside the saxophone shaped air inlet tube. Sometimes it just gets a hole rubbed in it eventually.

Charge air loss at throttle flap, tube will push off, due to worn out retainer tabs on tube.

All of the above will cause a DTC, and if it is in limp mode, it DOES have a DTC. Most likely a P0299 boost control negative deviation.