1.9 TDI AHH: Engine Misfire Issues & Solutions

Hello everyone.

I've been thinking for a long time about whether or not to sign up here to ask for help.

Here's the translation:

"This refers to the following vehicle:"

Volkswagen Passat 3B Variant, 1.9 TDI, 90 hp.
Year of manufacture: 1999.
MKB: AHH
Current mileage is approximately 167,000 km.

I am experiencing the following problem with the vehicle.
Sometimes, the car feels a bit sluggish when you press the accelerator. I wouldn't call it a direct loss of power, but rather a feeling of being slow to respond. When accelerating, the car just doesn't feel very responsive. It's almost like there's a small trailer attached to the back, which needs to be pulled along.
When it's running normally, it pulls beautifully and has very good throttle response.

The problem with this issue is that the problem mentioned above only occurs sporadically. I can't pinpoint exactly when it happens. I haven't found any correlation yet. I initially thought it might only occur during warm outdoor temperatures, but I've had to revise that assumption.
It's also possible that the car runs normally, then you go to fill up the gas tank, start it again, and everything feels a little sluggish again.

I've owned the car for a year now. Right from the beginning, I noticed that a vacuum hose had come off near the fender. Two workshops couldn't find the problem. I then started investigating myself and discovered that the hose connected to the EGR solenoid valve had broken. It was the hose that runs from the air filter box to the solenoid valve. I replaced the valve, but the problem hasn't been resolved.

"There's a 'ticking' sound coming from the engine compartment. This 'ticking' is clearly audible both inside and outside the car up to 80 km/h. The 'ticking' is speed-dependent. I estimate that it 'ticks' about 4-6 times per second when the car is stationary, but only under load. If I let the car roll down a hill in gear without using the accelerator, the sound disappears. When I press the clutch, it reappears, sometimes louder, sometimes quieter. Sometimes it's not audible at all. Two workshops have already tried to diagnose the noise, but without success. For me, it's impossible to locate the source of the noise with the hood open and the engine running; after about 2 minutes, you simply can't hear it anymore."


I'm slowly starting to get desperate. It's not that the system is completely terrible, but I know it could often be better, and of course, I'd like to achieve that level of performance consistently.

VCDS is available. However, random logging won't achieve anything. I simply don't know which control modules need to be logged simultaneously in order to troubleshoot. Furthermore, I wouldn't even know how to interpret or evaluate those logs.

By the way, the error memory is clear.

I would be very grateful for any help.

Best regards,
Sure, here is the translation of the text from German to English:

"Micha"

Wingcomander wrote:

Passat 3B Variant 1.9 TDI 90 hp. Year of manufacture: 1999. MKB: AHH

Hi,

I'm not familiar with a "99er AHH."

If it's the ALH, please log the MWB 4 and 8 readings simultaneously at full throttle while it feels sluggish.

ulf wrote:

Wingcomander wrote: Passat 3B Variant 1.9 TDI 90 hp. Year of manufacture: 1999. MKB: AHH Hi, I'm not familiar with a "99er AHH." If it's the ALH, please log the MWB 4 and 8 simultaneously at full throttle while it feels sluggish.

OK, thank you very much. I will take care of it promptly.

It's definitely the AHH. There were 3 VEP TDI engines in the Passat 3B: the AHU, the AFN, and the AHH... the AHH is the only one that meets Euro 3 standards.

Regards,
Sure, here is the translation of the text from German to English:

"Micha"

Wingcomander wrote:

It's definitely the AHH. There were 3 VEP TDI engines in the Passat 3B: the AHU, the AFN, and the AHH...the AHH is the only one with Euro 3.

OK, then the MWB should have the usual contents. So, please log it as described above.

There were 3 VEP TDI engines in the Passat 3B: the AHU, the AFN, and the AHH... the AHH is the only one that meets Euro 3 standards.

4. AVG is missing from the list.