AVB: Intermittent Freezing Issues

Hello everyone,

My 2005 Passat with AVB is having major problems. While driving, usually immediately after starting, the engine cuts out. Sometimes it restarts immediately, sometimes after a few minutes, and sometimes only after hours.

Error codes:

17965 Intake manifold pressure too high.
1274 Intake manifold pressure control valve, actuator error.
16688 Verbrennungsaussetzer 4. Cylinder.

In addition to that, the workshop provided me with the attached diagram. However, they are also at a loss and have recommended that I take it to a specialized workshop.

I would be very grateful for any suggestions on where I could start my search.

Best regards,
Thomas.

It's possible that the throttle valve in the intake manifold is permanently closed, which would obviously prevent the engine from starting. The valve is controlled by a vacuum actuator located behind the EGR valve (the black vacuum canister).

I think the metal plate on the valve might be loose or broken because it's only attached with rivets. If the valve is stuck or blocked, the intake manifold pressure will naturally become too high because the turbocharger pressure sensor is located *before* the valve. I attribute the misfires to a lack of oxygen.

The "STELLMOTOR" error message is misleading because the AVB unit doesn't actually have a motor; it uses a vacuum actuator instead.

The AGR valve with its flap looks like this:



The black device uses vacuum to operate the valve in the pipe. Disassemble the part as shown in the picture and look inside to see if the metal disc is securely attached to the shaft and rotates freely without sticking! The valve must always return to the fully open position without any force being applied to the device.

Get rid of all that black muck!

If everything looks okay, disconnect the hose attached to the black vacuum canister and see if the error still occurs.

Do you have a performance upgrade in the engine control unit? (Chip tuning?)

Hello,

Thank you for the quick response.

The vehicle doesn't have any chip tuning, but it already has about 300,000 km on the odometer. That black part is probably an electric actuator for the valve that shuts off the engine. So, the issue with the actuator motor might actually be the problem.

As soon as the storm subsides somewhat, I will examine the part.

What about relay 109? Is that still used in the 2005 Passat?

Regards,
Thomas.

meyert wrote:

That black part is probably an electric actuator for the valve,

No, it didn't. That part houses both the AGR valve and the shut-off valve, both of which are controlled by vacuum.
First, take the thing out and, above all, verschandeln it thoroughly, as the manufacturer instructed. Also, pay attention to the rubber seal. With a manual hand pump, you can easily test the function of the flaps while it's disassembled.
Your scan data isn't very helpful. The MWB 13 reading is okay, but the value for cylinder 4 is missing in the MWB 18 reading, even though that's the cylinder with the reported error, and the MWB 23 reading is completely missing. Are the original pump-injector elements still installed with 300,000 km on the clock?

That black part is probably an electric actuator for the valve, which is used to shut off the engine.

Deus Violentia wrote:

The "STELLMOTOR" error message is misleading because the AVB unit doesn't actually have a motor; it uses a vacuum actuator instead.

Yes, the black part is the diverter valve, but it is operated by vacuum, NOT by a motor! The vacuum is controlled by a valve upstream of it, and that is the only electrical component involved.

Hey Steffen!

Regarding the 300,000 km mark:

It's possible that the cross-section of the fourth intake port is so constricted that it no longer provides enough air to properly ignite the fuel-air mixture in the cylinder.

"If you've removed the AGR valve, please take some pictures of what it looks like inside."

@Steffen: Do you think he was given a PD element over the Jordan?

Regarding the posted rudimentary PD values, no. The rest that is missing would still be interesting.
However, the spray pattern of the injectors will eventually degrade over time, especially with the original injectors. I know of an AVB with 335,000 km (approximately 208,000 miles) that's still running with all its original parts: turbocharger, high-pressure pump, dual-mass flywheel, and catalytic converter. A nice older gentleman owns it and he's happy with it. There are examples like that.
The 1.9 AVB intake manifold doesn't just block the rearmost channel; the others remain open. Opening it up provides clarity.

I've already seen some strange "optical illusions."

Did a plastic lever break the retaining flap, or were the hoses connected incorrectly?

If the engine control unit (ECU) is functioning normally, it can almost only shut down due to the valve, which also explains the misfire.

Best regards, Rainer.

Hello everyone,

'He covered approximately 200,000 kilometers in record time when he was used as a company car. About 2 years ago, I replaced the wiring harness to the PD injectors under the valve cover due to misfires, and I also replaced the tandem pump due to pressure loss in the brake booster. Both repairs were successful. That's all that's been done so far. Therefore, the PD injectors are likely still the original ones.'

I will examine the folding part as soon as possible and report back. Regarding relay 109: Can I rule it out? There's a similar case in this forum with an AFN model, where it turned out to be a problem with relay 109.

Regards,
Thomas.

meyert wrote:

Regarding relay 109: Can I rule it out? There's a similar case in this forum with an AFN where it turned out to be relay 109.

I definitely wouldn't rule it out, because sporadic total failures + strange error codes are actually typical for relay 109.

If this helps you, I would be happy to send you a relay 109 for testing. Of course, the shipping costs are not free .

Hello everyone,

Here's the current status and an explanation of the circumstances surrounding the problem:

Over the past few weeks, the engine has intermittently started to misfire and has sometimes stalled. However, it could always be restarted after a few minutes. When it restarted, it sounded as if the combustion was gradually resuming in each cylinder.

I suspected a problem with the diesel supply, so on December 1st, I had the diesel filters replaced along with the oil change. After picking up the car from the workshop, it stopped again after about 2 kilometers. This time, however, it wouldn't start again after a few minutes. Because the battery was eventually completely drained, I had to call for a jump start after an hour. With the jump start, it started up again, but weakly. I took it back to the workshop. The next day, they read the error memory and checked the diesel lines for leaks. Otherwise, they couldn't find anything (it wasn't a brand-name workshop).

The crazy thing is: it's been running perfectly since December 2nd!

As long as it's running, it's being used so heavily by the lady of the house that I won't be able to work on it until at least next Monday. I will then check the pressure relief valve and relay 109.

@deus v.: Thank you for the offer. I might get back to you about it.

Best regards,
Thomas.

Hello everyone,

The problem had been gone for weeks, and over a distance of more than 1000 km. I therefore hoped that it might be related to the diesel filter or insufficient venting of the same.

Since the weekend, it has stalled and sputtered twice, but it hasn't completely shut off. Once, it started up immediately, and once, it started after a bit of sputtering.

Okay, I guess I'll have to follow your advice and inspect relay 109 and the flap.

Best regards,
Meyert.