Audi 80 TDI 1Z - Engine Failure Repair

Hello!

I'm facing a serious problem that I haven't been able to resolve despite considerable effort.

We are looking for more ideas from you, or any experiences you would like to share.


Here's an Audi 80 Avant TDI, manufactured in May 1994, that's experiencing problems. It runs fine under full throttle, and the idle is not an issue. However, the problem occurs when driving at 50-60 km/h in the city, or under any partial load conditions. Then, the car starts to jerk violently, making it very difficult to drive.
As I always say, with small gas adjustments. If you keep the accelerator pedal in the same position when it starts to stutter, it will only get worse.

It feels like it's misfiring on 1-2 cylinders!


So far, I have exchanged, swapped, or measured:

- Fuel injection pump replaced.
- Replaced the fuel injector for cylinder 3 with a needle lift actuator.
-then the remaining 3 nozzles were also replaced.
- Temperature sensor replaced.
- Timing belt replaced (it was due for replacement anyway), with meticulous attention paid to the timing.
- Precisely adjustable boost start (dynamic, for vehicles with an engine displacement of 3.94 liters or greater).
- Throttle potentiometer tested, it functions smoothly up and down without interruption.
- All vacuum hoses for the boost pressure control have been replaced.
- Replace the turbocharger pressure control valve.
- EGR valve replaced.
- Temporarily sealed the EGR valve with a piece of metal for testing purposes.
- Head disassembled, 2 hydraulic lifters replaced due to rattling, but they were the wrong ones, so 2 more were replaced, and the rattling is now gone.
- This will result in the need for new cylinder heads, screws, etc.
- 2 valves for the first cylinder, including valve springs, were replaced (although they were sealing properly, but the combustion in the first cylinder apparently wasn't as good as in the other cylinders).
- All valves have been ground and checked for smooth operation.
- Compression was subsequently measured, and all cylinders are good.
- Replaced the control unit with a different one.


NONE of these changes have made a difference; it seems I haven't yet addressed the root cause of the problem.


The car doesn't smoke, doesn't consume any oil, easily reaches 170 km/h on the highway, and 195 km/h downhill. The performance is good overall, but unfortunately, it's not great under partial load.

It's gotten worse now. It feels like a misfire in a gasoline engine. When I start accelerating, and it jerks, that jerking continues until about 3500 RPM at full throttle, and then it goes away.
Since this morning, the engine has also been experiencing occasional shaking, even when idling, but it usually resolves itself after a short time.

It's so powerful that the gear lever is really shaking back and forth.




Does anyone have any suggestions for other things I could check?



Thank you very much.
Daniel.




P.S.: I once adjusted the fuel quantity up and down using VCDS, but I didn't notice any change.
And can someone briefly explain how it works with the older control units? So, I don't have 32768, but 128 as the default value. But that's just a side note...

Hello,

I think there's probably no more well-known issue for the 1Z engine. Just try searching for '1Z AND misfire' or '1Z AND rough running.'

Yes, I'm familiar with that stuttering, which usually occurs with the 1Z engine, but you need to also read what I've already checked and/or replaced.

The main cause of the jerking is usually the injector nozzle, but I've already replaced it (the entire injector).

I'm familiar with that gentle jerking sensation, that kind of 'bonanza effect,' but I don't experience it either. It's like a misfire in a gasoline engine.

I don't think there will be anyone who says, 'This is it,' but I'm just looking for some ideas to get me thinking about things I might have overlooked or things I could still check.

As I mentioned, there's a significant jerking motion that sometimes lasts up to 5 seconds when the engine is idling, after which it stabilizes. However, it can also reappear a few seconds later and then disappear again.
The shaking while driving is so severe that the entire car vibrates, making it very difficult to drive.
The strange thing is that sometimes you can even accelerate without the problem occurring. Then, if you briefly put it into a higher gear, you can feel a slight jerk, and then when you try to accelerate, it becomes unbearable.



Thank you for the answer, but first.

Okay, I just entered the information into the search, and I want to apologize for not having searched earlier!

I'm going to unplug the tachometer signal wire tomorrow or the day after, just for testing purposes. However, that wouldn't explain the jerking at idle... but it's worth a try after all the work I've already put into this car.


Thank you very much.

I would just like to get some ideas to think about, in case I might have overlooked something, or something I could still check.


Okay.

Also, you should also check the KW screw. It wouldn't be the first one that's about to come loose. If I remember correctly, it should have '12.9' printed on it.

Okay, every time I replace the timing belt, I also replace the lower timing sprocket and install a new bolt. If the crankcase surface wasn't perfectly aligned, I lightly mill it down with a special hand mill to ensure a proper fit.

I replaced the timing belt because of the problem, and also installed a new gear including the screw.

I still remember air mass meters as a potential source of errors.

But please keep us updated. It seems to be a really stubborn TDI, especially since the ESP and all the injectors have already been replaced.

A faulty mass airflow sensor can cause exactly that!

I had that experience with a Seat Ibiza ASV. It ran smoothly when idling and under light load. However, when you let those 110 horsepower loose, it turned into quite a wild ride.

While driving, I connected VAG.COM and noticed that the mass airflow sensor (MAF) value was fluctuating wildly, dropping to 0.00, which caused the engine to cut off fuel.

A test drive with the MAF sensor disconnected resulted in the expected 80 horsepower (due to a fallback mode that the EDC uses for air intake), but there were no unexpected surges or issues.

After that, I plugged it back in, and it was working again - so it was just a loose connection in the plug.

m;

Hello everyone. I also have a small problem, and I didn't want to start a new topic, so this is a continuation .

So, it's about a Passat, model year 1995, with a 1Z engine .

Symptoms: Idle speed too low, hesitation/jerking under partial load.
Troubleshooting and repair: 4 new ESDs, 1 new VEP including initial injection setting checked and adjusted , new LMM, 109 new, cables checked, air removed from the DiFi system, vacuum system checked, AGR 'defective', speed sensor temporarily disconnected for testing, error memory cleared.
Result: Still experiencing stuttering, idle speed too low, uneven idle.

Do you perhaps have any other ideas for searching?

GolfMeister wrote:

NONE of these changes have made a difference; it seems I haven't yet touched the source of the error.

Hi,

I couldn't find relay 109 in your completed list. While this will eventually lead to the engine stopping, even so...

Is there anything useful in the error memory?

Hi Ulf, I think "GolfMeister" has resolved his issue... at least he hasn't posted anything in about nine months. "Mullemaus" is now experiencing a similar problem.

I would like to help, but I don't have any ideas right now either.

Just as a thought to get you started:

- Defective pendulum support on the generator.
- worn-out engine mounts.
- broken torsion springs in the clutch.
- Loose distributor ring for engine speed (if it may have play in the circumferential direction).

Regards,
Alex.

matthiasTDI96 wrote:

Hi Ulf, I think the GolfMeister has resolved his issue...at least he hasn't posted anything in about 3/4 of a year

Oops:oops::oops:You should also check the date of the posts.

Just as a thought provoker:

- Defective pendulum support on the generator.
- worn-out engine mounts.
- broken torsion springs in the clutch
- Loose distributor ring for engine speed (if it may have play in the circumferential direction).

Regards,
Alex

The clutch was the problem .

Test: Drive, induce jerking at a constant speed, lightly press the clutch and bring it to the engagement point, symptoms (jerking) disappear, release the clutch, jerking reappears. You have to figure that out first .

Thank you.

mullemaus wrote:

Symptoms: Idle speed too low, hesitation/jerking in the partial load range. Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. Driving, causing jerking at a constant speed, lightly pressing the clutch and bringing it to the engagement point, symptoms (jerking) disappear, releasing the clutch, jerking reappears. It takes a while to figure this out

. There are things that shouldn't exist: how can broken clutch springs, which should actually "brutally defend" the low-speed (starting on a hill without giving gas, etc.) in a VP engine, force it to drop into a lower range...?

mullemaus wrote:

It was the clutch

.
I'm not so sure about that. Experienced users of worn vibration dampers often have different observations. I experienced very strong jolting when starting until the clutch engages, and vibrations at 2500 RPM.

I think the stuttering disappears when you partially depress the clutch pedal because the system is stimulated differently.

I think the problem lies elsewhere, perhaps in the engine mounts.