1Z is not working correctly

Hello fellow TDI enthusiasts,

I'm having a problem with my TDI Passat, manufactured in 1994, with engine code 1Z and 206,000 km mileage. It hasn't been tuned.

So, the problem is a loss of power. When I press the accelerator, it feels like nothing is happening, the car drives like it has a huge trailer attached to it.
-> Car reaches a top speed of (according to). Speedometer reading: 190 (km/h), downhill: 210 (km/h).
-> The car barely makes any noise.
Fuel consumption is normal (5-6 liters per 100 km on country roads).
-> The car is shaking quite a bit at <approximately> I have the impression that the engine sounds somehow 'rough' or 'harsh.'

Okay, so here's everything I've done:

LMM temporarily exchanged -> no change.

Needle lift distributor tested using the 'Ran' knock method -> no misfires.

All sensors in the engine compartment have been checked with a multimeter (according to...). Information from 'Jetzt helfe ich mir selbst' regarding resistance and power supply.

AGR is shut down.

LDA integrated: Pressure at approximately 2100 RPM is 0.9 bar.

Air filter and diesel filter replaced.



As of today, I have a working VAG-Com: no errors are stored. I would like to read out measurement data, but unfortunately, I don't know exactly how to do it (for example, which channels would be interesting).

I tried the 10C tuning feature experimentally, but I didn't notice any difference whether it was enabled or disabled. (However, I connected it correctly, because if I turn it up too much, the car starts smoking, and I've also seen a colleague successfully install it...)

Please provide the German text you would like me to translate into English.
I'm kind of at my wit's end.
Maybe someone among you has an idea what it could be. As I mentioned, I now have an OBD2 tool and can read the codes if needed, but unfortunately, I don't know what to look for, as there's so much information available.



Thank you in advance!

Best regards.
David.

If my Alzheimer-addled brain isn't mistaken, I'd suspect the injectors! The hard running and instability could be caused by them! Regarding the mileage, the suspicion is also within the realm of possibility!

Perhaps you have the opportunity to test these things yourself, or to have them tested.

Hi.

Hold an ohmmeter between pump cable 1 and pump cable 2.
If you measure a resistance significantly above 10 ohms, you likely still have one of the old potentiometer-based volume controls installed, which can wear out with high usage and, in my opinion, could definitely cause such symptoms.
Don't ask me about the solution (whether it involves replacing the entire pump or just the sensor, which would require complex calibration on a test bench).


At approximately 6 ohms, you have a non-contact inductive sensor, which should ideally not cause any problems. Then the problem lies somewhere else...


A rough or harsh engine sound often comes from incorrect ignition timing. Therefore, it is also conceivable that the injection control system in the pump is malfunctioning in certain areas.
You can roughly measure this during a test drive --> A technical article about adjusting the pump.

Good luck.

@DeathAngel69

I've also considered the injectors, but: In this forum, people always talk about injectors when it comes to engine problems. But mine doesn't seem to have that issue. I have also been to a workshop (with a good reputation ) because of my problem. The master mechanic there said that the problem couldn't be with the injectors....

@Ulf

Okay, I just got back from a test drive (to warm up the car). So, field 2 shows '34' and field 9 shows '140'. According to the diagram, it's slightly below the ideal curve, but still within the tolerance range.

The resistance in the pump cable between pin 1 & 2 is 6.1 ohms, which is already the case for the newer part .

I may not know much about TDI engines yet (but you learn a lot from forums!), but I think the problem might be related to the fuel injection system, since the boost pressure seems okay and the 10C tuning isn't producing any power!

Okay, I just read the sensor data blocks at idle with the engine warm: Control unit 028 906 021 B.

Ad group 0.

F1: 40 F2: 40 F3: 0 F4: 25 F5: 112 F6: 111 F7: 79 F8: 133 F9: 160
F10: 120


Ad group 1.

F1: 840/861 F2: 5 F3: 1.42 F4: 82.8


Ad group 2.

F1: ... F2:0 F3:010 F4: 82.8


Ad group 3.

F1: ... F2: 272 F3: 395 F4: 69.5


Ad group 4.

F1: ... F2:0.0 F3:0.0 F4:38oder40


Ad group 13.

F1: -0.2 F2: 0.4 F3: 0.1


The red value is the only one that is not within the tolerance range, according to. Error database!

According to my VAG-Com, this value is called 'cold start value' .
According to the error database, it is called 'Duty cycle valve for injection start' . Is that the same thing? Could this valve be the cause of my problem?

Hi.

In idle mode, the duty cycle should be close to zero, resulting in maximum phase shift.
Your reading indicates that the pump is set too late or that there is a problem with the injection timing (see the technical article on pump adjustment).

Unfortunately, it's also possible that this is the old "1Z" problem – a loose crankshaft timing belt pulley. However, this often comes with poor starting behavior, which tends to get progressively worse.
Given the potential for serious consequences (often major engine damage), a thorough examination of the matter is highly recommended.

Hmm, I'm not comfortable working on the fuel injection pump myself; I'll probably have to take it to a workshop. Is there another way I can check if it's 'too late'?

How can I check if the pinion gear is loose? Does that mean I need to remove the timing belt cover?
When starting the engine, I actually don't have any problems; it always starts immediately...
The timing belt was replaced a year ago at a VAG authorized service center, approximately 25,000 km ago. (Did they install a new timing belt? The part number is...) Invoice 028 109 119 P (not 'D')

DocSnydor wrote:

Hm, I'm not comfortable working on the fuel injection pump myself; I'll probably have to have that done at a workshop. Can I check

this in any other way to see if it says "too late"?

Hi.

A simple electrical testing method is also described in the technical article.

Quote:

How can I check if the pinion gear is loose? Does that mean I need to remove the timing belt cover? When starting, I actually don't have any problems; -> it always starts immediately...

Set the engine to Top Dead Center (TDC) and then measure the camshaft position (at the transmission-side end) using a feeler gauge or similar tool.

If he's not having any starting problems, then the pinion gear is likely okay, and the issue is probably with the pump.

Okay Ulf, thank you very much. But I think I'd rather not, otherwise it might get even better .

I'll read the measurements again tomorrow morning on my way to work, at 3000 RPM / full load, and see what results I get...

Otherwise, I'm putting this matter on hold for now, as I'm going on vacation for two weeks soon, and I won't need the car then.
When I'm back, I'll contact Bosch service and have them check my injectors.

What's your 0-100 km/h acceleration time? Measure it and divide it.

Okay, my opinion is: If you can reach the maximum speed without any problems, then everything is fine.

??? 0-100 km/h acceleration time?
Starting from a standstill, shifting 3 times... How far should I rev the engine? Each time, a different value comes out. It depends on how quickly I can get into gear...

I can still check it, though.
I'm also going to test how long it takes to go from 60 to 100 km/h in 3rd gear under full load.

...it's better to test from 2,000 to 4,000 RPM in 3rd gear. Okay, we can compare them better here (Ulfscher Durchzugsrechner).

Best regards,
Uwe

Okay, I'll try to do that this afternoon...

What just occurred to me: I'm driving around without a muffler. It sounds strange, but it's true . Actually, it fell off recently. Since there wasn't much left to weld, and I'm quite short on money right now, I simply bent the pipe after the rear axle and welded a curved piece to it, pointing downwards.
The strange thing is the difference in sound before and after: there is no difference! Is this normal? If the rear silencer on our vacuum cleaner (1.6 D) is removed, the Golf has an amazing sound.

I was actually thinking that this might be related to a loose (twisted) internal component of the catalytic converter, as is sometimes described in this forum, which could also explain the loss of power. 'But nothing rattles in the cat, and I don't want to drive it without the exhaust because I'm afraid I won't be able to reattach it properly, or that something might break off due to rust.'

Accelerate from 0 to 100 km/h as quickly as possible. Then, check your car's specifications to see what the expected acceleration time should be (I estimate around 14 seconds), and that will give you a rough idea of how your car is performing. Whether you're at 14, 16, or a slower pace.

This allows you to quickly determine whether your engine's performance is consistent across the entire RPM range or not.

You can also take the permeability test. Since it only checks the performance in the mid-range, it's okay. You said you're reaching your maximum speed, so the performance in the higher RPM range is likely fine.

Hi!

Varianti wrote:

You can also take the permeability test. Since it only checks the performance in the mid-RPM range, it's okay...

Is this range (2,000 - 4,000 RPM) just the average speed range? Ulf, please recalculate the ventilation rate!

Our measured times often do not match the information provided in the brochures. Therefore, due to the potentially very long switching intervals, a significant source of uncertainty is expected when testing the 0-100 km/h acceleration.

Best regards,
Uwe

Uwe wrote:

2,000 - 4,000 RPM, is that just the average speed range? Ulf, please recalculate the ventilation rate!

Hi.

... no, because the DZR (Differential Pressure Regulator) is already designed for the area where TDIs (Turbo Diesel engines) produce "significant boost."

Depending on the engine, the turbocharger may still be lagging significantly, which can result in unreliable and incomparable data.

2000-4000 covers approximately 2/3 of the range of TDI vehicles (= 1000-4000).
And with that, the pull test with values ranging from 2000 to 4000 already provides a reasonably "comprehensive overall picture" of the engine's performance.

I would simply perform the test according to the DZR standard and compare the result with the calculated time. This already provides quite reliable results, if the parameters are entered correctly (roll-out test!!).