Two ECUs in a 1Z?

As a newcomer, I would like to welcome everyone in this forum.

Currently driving a Golf 3 TD powered by 100% rapeseed oil, but considering switching to a TDI engine.

I once read about a tuner who programmed the engine control unit (ECU) in such a way that a TDI engine could run perfectly on 100% biofuel.

Is it possible to install two control units in parallel, one optimized for a specific fuel type and one original (in case that fuel type is not available), with the ability to switch between them?

What aspects of the software can be modified?
For a diesel engine (Pöl), a cold start advance feature would be needed, which could be controlled by time or temperature, and possibly an earlier fuel injection start.

How susceptible are the TDI fuel injection pumps and their control systems to failure?

Thank you for all the answers.

Hearing aid.

Hello Hörbi,

Using two different control units doesn't really make sense. With the standard 1Z control units, only one driving program can fit in the unit. However, you could use twice as large memory modules and then switch between them mechanically.

Quote:

What aspects of the software can be modified? For the engine (Pöl), a cold start advance would be needed, which could be time-controlled, temperature-controlled, and possibly involve an earlier fuel injection start.

That's not a problem.

Quote:

How susceptible is the TDI pump and its control system to failure?

"Good question. It's best to avoid high RPMs when the engine is cold. However, I haven't heard of pump failures being more common than those experienced with 1.6D/TD engines. That said, I still wouldn't use 100% biofuel due to the direct injection principle."

In addition to the usual modifications such as fuel preheating, it would be beneficial to increase the opening pressure of the injectors.

Best regards, Rainer.

Hi Rainer,

Thank you for the message.
Yes, I am very familiar with the TDI issue.
I'm going to get a nozzle so I can take it apart and examine it. The AAZ injector has two valve springs, but there are two different versions.
These differ due to the connecting air chamber between the springs.
0.15mm and 0.7mm.
The newer nozzles with a 0.7mm opening are not suitable for use with pre-injection ("Pöl"), because the first stage opens too widely, resulting in too much fuel being injected before the main injection, even during a cold start.
It took me a while to figure out how the nozzles work.

I once read that TDI injectors also have two spring-loaded valves. If the clearance between these valves is too large, the injectors could be optimized. This would make a huge difference in cold starting performance. It's not a problem for me (I'm an extreme tinkerer) and I'm quite good at it.

Okay, let's get a nozzle first, then we can see what else needs to be done.

Best regards,
Hörbi

hi

For the two-stage TDI injectors (the Audi 80 initially only had single-stage injectors!), the opening pressure is usually specified, not a clearance value in millimeters.

The Golf 3 (EURO2) engines have a pressure of 190 bar in the first stage and 300 bar in the second.

Golf4 (EURO3 models) have pressures of 220/300 bar.

m;

EDIT: You can also have two different data sets stored in a single control unit. However, to switch between them, you'll need a laptop, VAGCOM software, and a data cable.

EDIT: You can also have 2 data sets stored in one control unit. However, to switch between them, you will need a laptop, VAGCOM software, and a data cable.

Yes, the coding for manual transmission and automatic transmission should be available (for AHU 11AG and 12SG). There are even tuners (like mozz, ulf probably knows him) who modify the control unit and add a two-wire connection to allow switching between two power levels.

I'm sure Rainer will be able to modify the two datasets. I think it makes more sense to recode using VAG COM, because TÜV Fuzzi won't notice anything. (With the early start of boost for the Pölitzer-specific version, NOx values increase - which invalidates the operating permit).

EDIT: I just saw that Rainer offers something that can be re-encoded -> http://shop.dieselschrauber.de/product_info.php/products_id/160

Hello,

The issue with the opening pressure is already understood. I've already tested and adjusted several nozzles.
The "coupling game," as I call it, is a crucial aspect when it comes to mating.

I've tested both versions in and on the AAZ engine and have now experienced their differences firsthand. Even with the chambered engine, there are significant differences in cold starting behavior when using biodiesel. This is even more noticeable with the TDI engine.
It is important to have a small initial injection before the main dose.
It wasn't entirely easy to figure out the game either.

As I said, I'll get a nozzle first and then see how and what to do next.

Best regards,
Hörbi