AGR Valve Stuck: 1Y Engine Problems & Fixes

Good day, fellow DIY enthusiasts.

I seem to have a somewhat rare problem with the AGR (Abgasrückführung - Exhaust Gas Recirculation).

It's a 1997 Seat Ibiza 6K with a 1Y engine.

When I start the device, it turns on, but after a few seconds, it starts "struggling" intensely, although it doesn't turn off.
The engine then runs very roughly, as if it's only firing on two cylinders.

I then removed the vacuum hose from the AGR valve, and lo and behold, the idle speed while stationary was fine.
Ich habe dann darauf hin das Ansteuerventil für die AGR genauer unter die Lupe genommen. Dabei ist mir aufgefallen, dass dieses immer voll geöffnet hat. Abgesehen davon dass ich glaube dass dieses im Leerlauf, gar nicht, bzw. nicht viel offen sein dürfte, macht es überhaupt voll auf. Normalerweise wird dieses ja über ein Tastverhältnis angetastet. Da hört man dann auch das Ventil "klopfen". Aber idling?
This control valve doesn't seem to be broken, because when I unplug the connector from the control valve, the valve closes, which blocks the vacuum supply to the EGR valve.
So, it's definitely heading somewhere. But why, and from where???
and why "full throttle"?

I thought, "Okay, let's just shut down the AGR, and that's that."
If I disable the EGR system, I experience a loss of power in the engine, and it also noticeably emits black smoke from the exhaust, which would actually suggest either a lack of air or excessive fuel injection.

These problems appeared suddenly, rather than gradually. (The car had been parked for a few weeks, and this issue occurred the next time it was driven.)

Can you help me with this?
Does anyone have any ideas about this?

Thank you in advance.

Best,
Chris

Hi.

Quote:

However, if I disable the EGR valve, I experience a loss of power with the engine, and it also noticeably emits black smoke from the exhaust.

This would actually suggest either a lack of air or too much fuel injection. }
Something else is likely broken in your car, and it's questionable whether it's the AGR valve. It needs to open and close correctly. Check it using an actuator test and possibly by removing it.

It is normal for the EGR system to have a high EGR rate at idle.

I would also check the throttle valve/shut-off valve.

Best regards, Rainer.

Hello Rainer,

Sure, thanks for the help!
I removed the AGR and inspected it; it's in good condition.

Quote:

It is normal for the EGR system to have a high EGR rate at idle.

Thank you for this information; I wasn't aware of that.

Quote:

I would also check the throttle valve/shut-off valve.

Good approach, but it's not available in my 1Y model.

Quote:

"...something else is definitely broken with you..."

...I think so too now! I'll keep searching. (The 1Y isn't rocket science, after all.)

What I would still be interested in knowing is:
The EGR rate in newer engines depends on several factors. For example, the opening angle of the EGR valve is monitored, among other things.
The 1Y engine doesn't have any of those features.

Is the AGR (Abgasrückführung - Exhaust Gas Recirculation) always adjusted strictly according to a "fixed scheme" here?

Sure, here's the translation:

"Thank you in advance."
Best regards,
Chris.

Is the 1Y engine a naturally aspirated diesel engine with a swirl chamber?
The injection system likely consists almost entirely of mechanical components.
The AGR (Abgasrückführung) system is controlled based on engine temperature, speed, and load.
In the AAZ engine, which is comparable in some respects, the valve only opens above 50°C, under partial load (switch on the ESP), and at an engine speed below 3200 rpm; it closes during sudden acceleration (according to Etzold). This requires a small control unit that can be mounted on a relay socket.
Does the poor engine performance occur with "active" EGR when the engine is cold or warm?
The power loss with black smoke is probably not related to the closed EGR system.
hg
Herbert.

Good morning, Herbert.

Thank you for your reply!

Quote:

Is the 1Y engine a naturally aspirated diesel engine with a swirl chamber?

Yes, that is correct!

Quote:

The injection system likely consists almost entirely of mechanical components.

"Yes, that's also correct. (Except, I suspect, for the valve for injection start, and the sensors for injection duration)."

Quote:

Does the poor engine performance occur with "active" EGR when the engine is cold or warm?

It always happens, regardless of whether it's cold or warm.

Tonight, however, I made a significant leap forward in understanding the problem.
The catalytic converter is so degraded that the back pressure in the engine becomes so high that, when the EGR valve opens, it forces most of the exhaust gases back into the intake manifold.
That's why, when the EGR valve is deactivated, the engine runs normally at idle. However, as soon as I reactivate the EGR valve, the engine immediately stalls.
Then, I slightly loosened the exhaust pipe before the catalytic converter, and sure enough:
All problems are gone. Now it also runs smoothly at idle with the EGR valve open. An initial test drive was also completed without any noticeable issues.
(Admittedly, it was pitch black.)
So, we're putting in a new exhaust system now, and then we'll see how it goes.

What, however, is bothering me again:

Quote:

In the AAZ engine, which is comparable in some respects, the valve only opens above 50°C, under partial load (switch on the ESP), and at an engine speed below 3200 rpm; it closes during sudden acceleration (according to Etzold). This requires a small control unit that can be mounted on a relay socket.

To what extent can I apply this to the 1Y as well?
On my 1Y engine, it's definitely the case that the EGR valve is fully open even when the engine is cold and idling. This means it's not being partially opened, but the EGR valve is 100% open.
I've experienced problems with the EGR system being active before. (Specifically, I've noticed hesitation or rough running at partial throttle.)
Therefore, the breather hose for the EGR system has sometimes been disconnected. (This resolved the issue of engine misfires at partial load).
(...but they could also be early signs of a blocked catheter. I will observe this more closely in the near future.)

Thank you again for your help.
Best regards.
Chris.

The injection start and injection duration are also mechanically regulated within the ESP (Electronic Stability Program).
Do you have a repair manual for the car? I can only guess how the AGR (Abgasrückführung) is wired. The temperature sensor, if present, should be checked.
But first, let's talk about the exhaust system; you're right about that.
hg
Herbert.

Unfortunately, I don't have a repair manual for that .

Hi,
However, it is possible to find information about those years. With publications like "This is how it's done" and "Now I'll help myself," you could still learn a lot about the construction methods of that era.
VW offers RLF (Repair Leaflet) documents through ERWIN. Purchasing a single hour is sufficient.
hg
Herbert.