TDI Tuning: Performance Upgrade for 10 Euros

Hello everyone,

I've been thinking about the '10-cent tuning' for PD-TDIs, and I find the small (and weather-dependent) performance increase achieved by manipulating the fuel temperature sensor to be unsatisfactory.

The extension of the injection duration can also be achieved relatively easily using an electronic circuit, with material costs of around 10 euros.

With my modification, I achieved approximately 20% more power in a Lupo 3L, as measured by the Ulf-style exhaust flow calculation method, without producing any black smoke.

The circuit is triggered by a button and then immediately and statically extends the injection signal.

The extension time is adjusted using a potentiometer.

When the circuit is activated in the low-speed range, black clouds appear.

So, what's still missing is a proper control system.

Anyone who is interested in further development and has the necessary knowledge in electronics is welcome to contribute with a few suggestions.

If you are interested in my circuit diagram, please send an email to [email protected].

Bye driklau.

Warning! Using the circuit described above will void any warranty claims against the vehicle manufacturer and will invalidate the vehicle's approval for use on public roads.

I'd be interested to know how you solved it. I have some knowledge of electronics. Why don't you just post the schematic?

Here is a link from the Passat 3B forum. http://www.passat3b.de/phpBB2/viewtopic.php?t=17665 In it, you will find instructions on where and how you can upload images online for free.

Regards,
Private.

2. I'll try to put the circuit diagram online. Sorry!
http://img33.

/img33/8753/Schaltplan17.gif

hello,
I've been thinking about that too.
but with a microprocessor.
Basically, all you need to do is measure whether a signal is present.
Then, for example, you could measure how long it takes for the process to complete and inject the substance for 10% longer.
The risk, of course, is that the microcontroller might malfunction at some point, causing the motor to stop working.
First, I need to examine the original trigger signals for the PD elements.
The further problem is that, as a regular person, you often don't know exactly how much more you can add, which could potentially damage the engine.

With a microcontroller, it would also be no problem to implement a map-based control system (using speed and other signals).
At a maximum injection frequency of around 100 Hz, even a microcontroller might find it boring.
greetings

Simple rule:
If it's smoking, there's too much.
You either need to build an online tuning interface for your calibration data, or you can fine-tune the settings through test drives (or using a dynamometer).
But don't worry, a TDI engine doesn't die that easily.
Since the turbocharger pressure is not being increased, the smoke starts long before other problems arise.
During my attempts, the transistor once burned out.
It was smoking a lot, but the engine is still running.
Regarding tax deductions, here's a tip:
The control signal (+) is generated centrally for all PD units (brown wire in the Lupo), and it determines the start and duration of the injection. The ground connection (all other wires) controls which cylinder is currently being activated.
Have fun measuring.

Hello Driklau,

Great idea - excellent design.

'Simple rule: If it's smoking, there's too much.'

I would say it might also be too low – the boost pressure.


Furthermore, there's the question of how to move the very late injection timing forward. Has anyone ever tried moving the crankshaft sensor? That would extend the possible injection duration.

Here's the translation:

'One more question: If the MOSFET is broken, meaning it's always conducting and therefore constantly activating the valves, wouldn't the engine run continuously because it would be constantly injecting the maximum amount of fuel?'

'The wiring looks great, but has anyone considered that increasing the injection duration will always increase the internal pressure within the pump, bringing it closer to the bursting pressure of the piezo injectors (PDEs)? A PDE costs at least 500 euros.'

Ben1972 wrote:

Very nice with the wiring, but has anyone thought about the fact that increasing the injection duration always increases the internal pressure within the pump, bringing it closer to the bursting pressure of the PDE? A PDE costs at least 500 euros, you know.

Hi Ben,

So far, I thought that the injection pressure only depended on the engine speed in combination with the angle of the injection cam .

How can simply extending the injection duration increase the pressure?
Or does the fuel injection cam become "steeper" along its path, for example, to increase the injection rate?

So far, I thought that the injection pressure only depended on the engine speed in combination with the angle of the injection cam .

How can simply extending the injection duration increase the pressure?
Or does the injector cam become 'steeper' in its profile to, for example, increase the injection rate?


You are also correct in your assumption: As the speed increases, the internal volume of the pump increases due to the higher speed of the drive cam.

The camshaft of the PDE (Pre-injection Diesel) has a triangular speed profile due to the shape of the cam. At the start of injection, the speed is relatively low, but it steadily increases during the injection period (which is not referred to as 'injection duration' in the context of PDE). Eventually, the cam reaches the descending portion, causing the pressure to decrease. However, the injection occurs so late that there is not enough time for proper air-fuel mixing and combustion, and the injected fuel is only converted into soot.

Ben1972 wrote:

At the start of the injection, the speed is at a relatively low level, which steadily increases during the injection duration (in the context of PDE, one does not speak of injection duration). At some point, one is naturally on the descending part of the cam profile, so that the pressure also decreases again.

Hmm, this is getting tricky.
What does your descending branch mean?
a) the descending flank of the injection nozzle = filling phase of the pressure die casting (PDC) process.
b) that the slope of the cam profile decreases again, which reduces the pumping rate, but allows for further injection?

However, if a portion of the rising camshaft lobe is so steep (lift per degree of rotation) that it cannot be utilized (at least in the higher RPM range) due to the risk of bursting of the piezo injectors, why is the camshaft lobe shaped in such a "dangerous" way ?

Here's a link with a description of the PD injection process:
http://kfztech.de/kfztechnik/motor/diesel/pumpeduese.htm

@ulf
Was your camshaft not originally misaligned towards a later timing? If so, then the engine would already have been running, at least partially, in the range that is being used additionally here.

mcgyver2k wrote:

@ulf Was your camshaft not originally misaligned towards a later timing? If so, then the engine would have already been running, at least partially, in the range that is being used additionally here.

No, not exactly.
The pressure drop valves (PDVs) were theoretically opened before the injection ramp began (at which point nothing can be pumped due to lack of pressure), and then closed at the point on the ramp that corresponds, for example, to 3/4 of the load.

@ulf
Was your camshaft not originally misaligned towards a later timing? If so, then the engine would have already been running, at least partially, in the range that is being used additionally here.

/viewtopic.php?t=5257&highlight=pd

Okay, just a quick comment on the side, which might not necessarily contribute to the discussion about this tuning option, but I still want to mention it:

How long do you think it will take for someone to turn this circuit diagram into a great and effective power supply unit that's sold on eBay? Should we place a bet on it?

Shall we place a bet?

Haha... good point! But the single-resistor version will still be able to fool enough people... and it's just so easy to build!