Turbo AAZ to Turbo 1Z Conversion Guide

Hi again. I have a rather unusual question.

Is the turbocharger from the old AAZ engine fundamentally the same as the one from the 1Z TDI? (same displacement)

The AAZ engine seems to have a kind of 'self-regulation' for boost pressure, as far as I can see. The 1Z engine achieves this through the boost pressure valve.

Would it work if you replaced the turbochargers? The ones with the 'self-regulation' via the wastegate valve? I have 3 AAZ turbochargers here, but none of them are 1Z. And my turbo is leaking a little bit of unburned oil .

Would that work?

Hi.

In principle (wastegate with pressure-controlled actuator), both turbochargers should be identical.
In the 1Z engine, the boost pressure is controlled by the engine control unit (ECU) through a solenoid valve, which is how the boost pressure regulation of the 1Z is achieved.

However, I can't say for sure whether the AAZ turbocharger is large enough for 15 more horsepower. If the AAZ turbocharger receives roughly the same boost pressure as the 1Z (around 0.9 bar), it shouldn't be a problem, given the same engine displacement.
Then, only potential mechanical fastening issues would need to be resolved.

The AAZ Turbo easily produces slightly more than 1.4 bar at full throttle; it should have around 0.6 bar as standard, and achieving 1 bar is no problem.

However, I wonder what the engine control unit (ECU) will do if it can no longer control the solenoid valve, or if the boost pressure deviates from what the ECU would prefer.

Stukov wrote:

However, I wonder what your control unit says about it when it can no longer control the solenoid valve, or when the boost pressure differs from what the control unit would prefer.

"In my opinion, the AAZ turbocharger should, in principle, be adjustable in the same way as the 1Z turbocharger, by manipulating the boost pressure, meaning you could simply connect the hose from the original turbocharger's pressure sensor to the AAZ turbocharger."

Regarding "expected boost pressure for a given turbocharger control valve setting," the engine control units seem to be generally quite tolerant, so that the "wrong" turbocharger might go unnoticed with a bit of luck.
If necessary, slightly twist the charging rod; that should do the trick.

According to my local VW dealer, their computer indicates that the 1Z has less boost pressure than the AAZ turbo. In my opinion, it should be possible to adjust the boost by modifying the turbocharger control unit. Whether it's an external or self-regulating system, the principle should be the same, right? I don't want to disassemble everything and then just have it running in a limp mode .

Ulf might be right. You could connect the hose that currently goes from the turbo to the wastegate directly to your solenoid valve instead, and then seal off the connection to the intake manifold. The engine control unit measures the boost pressure and applies pressure to the wastegate when the desired boost pressure is reached. You can then fine-tune the rest using the wastegate adjustment.

After thinking about it a second time, it seems quite feasible.

If you don't do it this way and simply install the AAZ turbocharger with self-regulation, the control unit will try to regulate the boost pressure when the target pressure is reached, but it won't be able to. In that case, your wastegate would have to be adjusted perfectly so that it operates exactly as the control unit wants it to. Otherwise, it will go into limp mode because the control unit cannot regulate the boost pressure.

By the way, even in the AAZ engines, some turbos were partially controlled by a solenoid valve. It seems this was integrated with the introduction of the EGR system in the AAZ. According to reports, when the EGR system is active, this solenoid valve reduces the boost pressure slightly.

Hello,

Unfortunately, I'm not familiar with the AAZ and its regulations.

The 1Z engine has a wastegate that opens at a maximum pressure of 0.6 bar. However, the control line of the wastegate is not directly connected to the intake manifold pressure, but rather regulated by a solenoid valve (boost control valve). This causes the "boost pressure" at the wastegate inlet to be artificially lowered, so that only 0.6 bar is present even when the intake manifold pressure is 1.0 bar. Therefore, the wastegate is being "lied to" by the engine control unit (ECU).
If you can adjust the AAZ turbocharger to a base pressure of 0.6 bar, it should work.

Can someone explain the turbocharger boost control system for the AAZ engine to me? (Does it not have a wastegate?)

'Yes, the AAZ turbocharger has a wastegate, and the default wastegate setting should be 0.6 bar. That's the standard boost pressure. The wastegate on the AAZ turbocharger is directly exposed to the intake manifold pressure, so when the boost pressure reaches 0.6 bar, the wastegate opens. This would mean that the AAZ turbocharger could potentially be used as a direct replacement without even needing to adjust the wastegate, as it would be set to the same value as the 1Z turbocharger. You would just need to connect the solenoid valve to the wastegate.'

Stukov wrote:

Yes, the AAZ turbocharger has a wastegate, and the wastegate setting should normally be 0.6 bar. That's the standard pressure. The wastegate of the AAZ turbocharger is directly exposed to the intake manifold pressure, so when the boost pressure reaches 0.6 bar, the wastegate opens. This would mean that the AAZ turbocharger could be used as a direct replacement without even adjusting the wastegate, as it would then be set to the same value as the 1Z turbocharger. You would just need to connect the solenoid valve to the wastegate.

I agree.