Broken VTG Rods? Get Expert Repair.

Hi,

After almost 9 years of faithful service, my car is starting to have problems.
I'd like to hear your opinions on the following:

Auto: Seat Ibiza TDI Bj 10/2000. ASV, 110,000 km.
Tuning: Since 50,000 km, using 0.216 injectors, the power box is set very conservatively, I'd say about 130 hp after the crankshaft. Boost pressure is regulated using a voltage divider to 1.1 bar for the holding pressure / 1.3 bar for the overboost. For diagnosis, the power box and the boost pressure increase circuit were removed.

Symptom:
* When accelerating, the boost pressure increases from 3000 RPM to 1.5 - 1.7 bar. This happens regardless of whether the accelerator is pressed abruptly or gradually, or in which gear the car is. I have a manual pressure gauge installed, and its readings match those obtained by reading the data via VAG-COM.
* The turbocharger builds boost very quickly, even at low engine speeds.
* The error code in the diagnostic memory indicates a "intake manifold pressure control differential" error. However, I haven't triggered the limp-home mode yet because I've always been hesitant and probably haven't exceeded the control tolerance for long enough.

Suspected.
a) VTG can no longer adjust the guide vanes to the minimum pressure build-up.
b) N75 valve defective.

My previous attempts at diagnosis:
1) The turbocharger vacuum control valve (N75) was replaced along with the EGR valve. The exact same behavior was observed.
2) Using VAG-COM, the 'Output Test' and 'Basic Settings' for measuring block 11 were performed. It is clearly visible that the VTG rod is moving cyclically by approximately 7mm.
3) Manually adjusted the VTG using a 60ml syringe. It operates smoothly without getting stuck at the limits.
4) Vacuum hose disconnected from the turbocharger pressure sensor. Acceleration test performed, resulting in behavior similar to an SDI engine (lacking turbo boost). Approximately 1 bar of boost pressure is achieved from around 3500 RPM.
5) VTG rod inspected. The length has not been altered, and the safety coating is still as original from the factory.
6) Measurement data block 11 logged, please see the attachment to this post. My interpretations: The actual boost pressure is clearly above the target value. The duty cycle is constantly at 100% (see around time=30s), even with large deviations, yet the boost pressure does not decrease.

Well, I think there are two possibilities here.

Either the control of the vacuum actuator on the ATL is defective, but I consider that unlikely because I swapped the solenoid valve with the one from the AGR and nothing changed.

Or, surprisingly, the pressure control valve/VTG mechanism is so corroded that the guide vanes can only be adjusted for medium to high pressure.

Okay, how about the pressure ratio? Does a 100% pressure ratio mean that the N75 only allows ambient pressure to pass through to the pressure sensor? And does 0% pressure ratio mean maximum vacuum, i.e., maximum pressure buildup in the ATL?

Please share your thoughts and opinions on this matter.
Thank you in advance.


Georg, who has been in Scotland for three years and still doesn't know which workshop he can go to.

Georg_G wrote:

* When accelerating, the boost pressure increases from 3000 RPM to 1.5 - 1.7 bar. . . . Using VAG-COM, the 'Output Test' and 'Basic Settings' for measuring block 11 were performed. It is clearly visible that the VTG rod is cyclically moved by approximately 7mm.

This fits well together if one assumes that the last ~3 mm are blocked in the direction of "VTG open".
As you already wrote:

Quote:

Suspicion: a) VTG is no longer able to adjust the guide vanes to the minimum pressure build-up. The pressure chamber / the VTG mechanism is, surprisingly, so corroded that the guide vanes can only be adjusted for medium to high pressure.

Quote:

Oh yes, how about the valve ratio? Does a 100% valve ratio mean that the N75 only allows ambient pressure to pass through to the pressure sensor? And does 0% valve ratio mean maximum vacuum, i.e., maximum pressure build-up in the ATL?

Yes.

Hello Ulf,

Thank you for your response.

I just want to rule out that it's the N75 turbo before I install a new one. Here's something else I thought of:

A few weeks ago, the vacuum hose that supplied the N75 valve and the EGR valve detached from the air filter housing. As a result, both valves sucked in "dirty" air for a few days before I noticed it.

Okay, both valves are working perfectly in the actuator diagnostics. However, I'm hesitant to replace the N75 valve because it would cost me £100; the replacement turbo actuator and installation would be £600, and I suspect the turbo actuator is more likely to be the problem.

Here's the translation:

"Also, something else: Shortly before the faulty turbocharger pressure regulation started, I had the middle and rear sections of the exhaust system replaced. Could that (possibly increased back pressure) have anything to do with my problem?"


Best regards,
Georg.

ulf wrote:

Georg_G wrote: * . . Using VAG-COM, the 'Output Test' and 'Basic Settings' for measuring block 11 were performed. It is clearly visible that the VTG rod is cyclically moved by approximately 7mm. This fits well together if one assumes that the last ~3mm are blocked in the direction of "VTG open".

But how does that fit together with the diagnostic attempt (4)?
as described by the user who started the thread in the initial post?
Without a connection to the printing system, the VTG appears to be fully accessible in its open state.
"Can I go?"

Best regards, Klaus.

Georg_G wrote:

Both valves sucked in "dirty" air for a few days before I noticed it. Well, both valves are working perfectly in the actuator diagnosis. However, I don't want to replace the N75 just based on suspicion because it will cost me £100

. Instead, connect a temporary vacuum-operated LDA to the vacuum line just before the turbocharger control valve using a T-connector: if the LDA shows a difference of less than 0.1 bar compared to the atmospheric pressure when the boost is too high, the pneumatics are okay.

Quote:

By the way: Shortly before the faulty boost pressure regulation occurred, I had the middle and end sections of the exhaust system replaced. Could that (possibly increased back pressure) have anything to do with my problem?

IMO no. With too much back pressure, the tendency is probably more towards a sluggish boost pressure build-up.

Hello.

Thank you for the comments so far.
I bought a new N75 for a cheap price on eBay and installed it. The result: no improvement.

Then the VTG mechanism must be the fault of the Uebeltaeter.

Can someone please help me with the following information?

The correct designation of the turbocharger installed in my vehicle.
Car: Seat Ibiza TDI, 110 horsepower, engine code ASV, manufactured in 10/2000.
I went to a dealer here who also works on Seat cars, and he said 028145702N.
When I search for this number on Google, the ASV doesn't appear in the results, but rather the AFN, among other things.

Does anyone in Germany know of reliable companies that offer remanufactured turbochargers for exchange?

Does anyone know how much labor time a Seat workshop typically estimates for replacing a turbocharger?



Thank you for the answers!

Greetings, Georg.

Georg_G wrote:

Car: Seat Ibiza TDI 110HP, engine ASV, year of manufacture 10/2000. I went to a dealer here who also works on Seat cars, and he said 028145702N. When I Google this number, the ASV doesn't appear, but the AFN does, among other things.

According to the file, the number is correct for your ASV.

But do you really want to have the loader replaced (following the "standard workshop procedure"), even if it's possible that only a small piece of pneumatic hose is partially blocked or kinked?

Hello Ulf,

Quote:

But do you really want to have the entire loader replaced (following the "workshop procedure"), even if it's only a small piece of pneumatic hose that is partially blocked or kinked?

Which hose connector could be relevant here? In the actuator diagnosis, the control of the pressure sensor works with a visible movement of the VTG rod.

I performed the test with the new N75 while disconnecting the ambient pressure hose (the hose that connects to the air filter housing) to rule out any potential restrictions.

I could replace the N75 vacuum hose sometime. There's a heat shield around it, which should slide easily over a new hose.
I have a hose lying around that is used for the leak return lines (is "leak return lines" the correct term? I mean the return line for excess diesel to the ESD). It looks very similar in diameter.

Georg.

Georg_G wrote:

Which hose section could be relevant? In the actuator diagnosis, the control of the pressure sensor works with a visible movement of the VTG rod.

. . but the movement is too small, as if, for example, some residual vacuum remains.
As I mentioned before, I would check that using a vacuum-assisted LDA.

Quote:

I performed the test with the new N75 with the ambient pressure hose disconnected (the hose that goes to the air filter housing) to rule out any potential bottlenecks.

That's a good approach.
I would simply run the actuator diagnosis again, and while the "VTG closed" state is active for 10 seconds each time, disconnect and reconnect the hose to the charge air pressure sensor. If the travel distance remains small, you could try as a last resort to use a syringe to push the remaining ~3mm of travel back into position using overpressure.

Where you mention that the ventilation hose was disconnected on the oil filter side, I would suggest that you check the hose connection there for kinks or excessively sharp bends.

A too-high boost pressure can occur because the wastegate (VTG) doesn't close quickly enough. This could be due to a jam in the turbocharger's wastegate mechanism, or it could be caused by the vacuum being released too slowly (if the N75 valve is trying to reduce the vacuum, but the atmospheric pressure cannot be regulated quickly enough).

Hello!

Regarding this, I would like to mention that I also had problems with the VTG (Variable Turbine Geometry) in my Golf. However, it was a different issue; it was stuck in the other position, so the turbo wasn't producing any boost at all.
This is a somewhat peculiar mechanism that tends to get dirty and jam.

So far, I've received helpful advice in this forum, which allowed me to remove the turbocharger myself, disassemble it, clean the variable geometry turbine (VGT), reassemble it, and then reinstall it.
It's been over a year, and it still works perfectly.
That certainly saved me hundreds of euros on a new turbo. Thanks again to the helpful members here!

If you are certain that the problem is definitely related to the VTG (Variable Transmission Gear), then...
You could try having something like that done at a good workshop.

Hello Georg,
If you still need the load number, please send your vehicle identification number (VIN) to me via private message.

Let's try a different approach: Is the shut-off valve fully open (in the open position), or is it stuck in a partially closed position?