AGR Valve Check: Diagnosis and Control

Hi,

'Since I've been searching for the cause of the power loss under full load in my Golf 1.9 TDI (1Z) for quite some time, I'm currently investigating whether the problem might be related to the AGR valve.'

Hatte alles mögliche gewechselt, LMM, Magnetventil, Dieselfilter, Druckschläuche die auch nur ein wenig brüchig waren. Kea refinement.

'I'm now of the opinion that the EGR valve isn't being activated, because whether I have the connector plugged in or not, the engine behaves exactly the same. There's no significant increase in soot production, etc. I suspect the valve isn't receiving any power, because under full load, around 3000 RPM, there's suddenly no more power (in 4th gear at 100 km/h and 5th gear at 120 km/h). It's as if the turbo shuts off, if it was even active in the first place!'

'For testing, I connected a 12V lamp with an extended cable to the connector for the EGR valve. It should light up (or at least glow) as soon as it's activated. Is that correct? Or are those very low-wattage devices that activate the EGR valve? Anyway, I didn't see any light.'

That means either there's absolutely no power getting through (the power supply is completely broken), or it's impossible to proceed like this! Am I completely wrong in my thinking? Unfortunately, I don't have a multimeter!

Maybe one of you could try this and let me know if anything shows up (or lights up) on your voltmeter.

I haven't replaced the AGR valve yet, but recently a friend with a 1Z engine tried connecting his engine control unit (ECU) to mine, as the ECU numbers were the same. It only started briefly and then immediately shut off! Does anyone understand this? Could it be related to the immobilizer? Are the ECU numbers absolutely identical?

I'm desperate.

Hello,

"In my opinion, the ECU should monitor the coil resistance of the EGR solenoid valve. If you connect a (low-resistance) light bulb in parallel with the coil, the ECU might detect a fault (short circuit) and, to protect the electronics, stop supplying power to the coil."
If you have a diagnostic tool, there should be an error code related to the engine control unit (ECU) displayed here.
Therefore: if you need to measure the voltage, do so while the solenoid valve coil is plugged in, using an analog voltmeter. You can create a temporary adapter using two wires for this purpose.
Okay, but if I were you, I wouldn't do that just yet. Instead, first check if the power loss still occurs when you disconnect the vacuum hose from the EGR valve (not the solenoid valve, but the one on the intake manifold) and plug the hose with a screw. The screw should be inserted into the hose towards the solenoid valve; it's meant to prevent the vacuum system from losing too much vacuum and drawing in dirt.
AGR valves and AGR magnetic valves are two completely different components; please refer to Ulf's article on AGR for more information.
What you see in the picture is the AGR valve with the shut-off flap.
Do you still experience a loss of power and black smoke? Remove the EGR valve (the one on the intake manifold) and check if it's really sealed and not stuck.

Best regards, Rainer.

Hello,

Have you ever had the error memory read out? If so, what were the entries?
If you want to use a different control unit, it must first be adjusted. This requires specific codes. If it is not adjusted, the immobilizer will be deactivated.

Hi,
Regarding the 'same' engine control units: if your vehicle has a Waste Heat System (WFS), the combination of the engine control unit (ECU) and WFS must be re-synchronized when the ECU is replaced.

Regarding the AGR (Agricultural Land Reserve): You can use a light (e.g., a 5W taillight; please do not use headlights).

The car will also function without the EGR valve. So, first, disconnect the hose from the mechanical valve (located at the rear of the engine, between the intake manifold and the exhaust) and seal it with a suitable screw. Then, your car should accelerate normally and without excessive smoke.
If that doesn't solve the problem, the (mechanical) valve may be so dirty that it no longer seals properly, and the engine is constantly getting exhaust gases. In that case, you should unscrew it (four screws; but wait until it has cooled down) and clean it thoroughly (carefully remove it from the intake manifold so that not too much of the dirt falls in).
Check the cleaned valve for leaks and reinstall it -> Test drive.
If everything is okay now, I would leave the hose as it is .
If the error persists, it was obviously not the EGR .

Hello everyone!

I had already asked where the valve was located, but that turned out to be irrelevant.
Does anyone happen to know if the EGR valves are the same and fit in the same location for a Passat AJM 85KW PD?

Apparently, once again, this technique has been used to treat consumers as test subjects.

To me, your problem sounds like it might be caused by a different issue, such as the engine running in a limp mode. If the EGR valve is always open, why is it only pulling below 3000 RPM?
And: Shouldn't he at least run 170 (I'm not sure)?

Regards,
Thorsten

Mensch seit ihr alle fix!! Thank you.

I'll hold off on checking the AGR solenoid valve (black part) for now, whether with a lamp or not. And I'll disconnect the hose from the AGR valve (white part) and seal it with tape or a screw.
The AGR valve itself, not right? It needs to let air in or out, correct?

And then, tonight is the crucial test drive. Hopefully, it will work properly this time.

I will report.

Okay! You can leave the hose connection on the AGR valve on the intake manifold open. This valve is closed by a spring, so if you disconnect the hose, it will always remain in the "closed" position.

Best regards, Rainer.

Regarding Thorsten:

I didn't write everything in detail at the beginning, but I'll eventually reach my own top speed of 180 km/h. HOWEVER, as soon as the boost stops, I have to completely take my foot off the accelerator and very gently apply diesel to reach that speed. As soon as I press the pedal even slightly harder, the boost cuts out again!

But it's not fun like that, especially since I often drive longer distances with a fully loaded vehicle. And usually, the 'GRA' (presumably referring to a driving assistance system) is always active, and it always accelerates to the maximum to reach the previous speed.

Hello,

When the engine is running under full load, the EGR valve is always closed.
"Even if the AGR doesn't receive any coolant (for whatever reason), this has absolutely no effect at full load."
The AGR (Abgasrückführung) system can only cause problems if the valve does not close completely (usually due to a mechanical issue). In this case, a noticeable loss of power can be felt under full load.

1881 wrote:

I didn't write it out in full detail at the beginning, but I will eventually reach my own, even 180, BUT I have to completely take my foot off the pedal at some point, and very carefully add diesel to reach that speed. As soon as I press the pedal a little harder, the boost cuts out again!

Hi.

"In my opinion, this is typical behavior for the emergency mode of older TDIs when the turbocharger is experiencing excessive boost pressure."
Okay, let's take a look at the solenoid valve for the boost pressure control --> try replacing it as a test.

You can check if the wastegate is still working by applying a lot of pressure to the charger chamber with a large syringe. At the latest when your fingers hurt (around 0.6 bar), the piston rod should move noticeably. If it doesn't, the chamber or the charger might be faulty .

So, I bought a new solenoid valve because it was making a ticking noise, and I hoped that was the problem. But it was just a hope, nothing more.

Part No. 028 906 283F (30 Euros)

I'm going to take it for a test drive now with the hose disconnected from the EGR valve. I'll report back tomorrow morning.

Quote:

So, I bought a new solenoid valve because it was making a ticking noise, and I hoped that was the problem.

Hi.

Then, from my perspective, there's still the wastegate check... or, to be absolutely sure, a test drive with a (temporary) boost pressure gauge. You can simply connect it using a T-piece on the hose leading to the engine control unit.

If that doesn't help either --> have the error memory read out!

Damn, the test drive with the detached hose didn't make any difference.
Engine stall at 110 km/h (4th gear) (3,100 RPM) or 120 km/h (5th gear) (2,900 RPM).
It ran completely normally in the city.

Today, I have to remove the EGR valve, clean it, and hope for the best.

To make sure I'm expanding the right thing:
Es ist ja dieses runde Blechding das an einem Gußstück mit 2 längs- & 2 quergeschraubten Imbussschrauben befestigt ist? Und es geht ein schwarzer Gewebeschlau, nicht dieser blaue und rote Schlauch, von dem Blechding ab. RiSure.

Please be very specific, as I don't want to unscrew anything incorrectly and potentially break something else.

Und wenn ich das AGR-Ventil in der Hand habe, müsste es mit Ruß ja so richtig verstopft sein. SLet's do it.

First, you need to get a large Allen wrench.

Hopefully this will work. If this doesn't do anything, then I'll do the Ulfchen wastegate check. Where is the container where I should attach the syringe?

Hello,

Even though I may be repeating myself:

Please have your vehicle's diagnostic data read out (even if you have to go to a workshop for it). This would certainly help narrow down the cause of the problem.

1881 wrote:

If that doesn't work, then I will do the Ulfchen wastegate check. Where is the container, where I should attach the syringe?

Hi.

The component is located somewhere on the exhaust side of the charger. I'm not familiar with the installation position for the 1Z model.

Okay, so I removed the AGR valve. But it looks like it's in normal used condition. What exactly should be cleaned there? I pushed the valve towards the metal can. It requires some force, but I guess that's normal. I would say it moves freely enough? Or should it be very easy to push? Can I open the actual valve (vacuum chamber) somehow and clean something inside, or do something else while it's removed?