PD TDI: Shaking, Vibrating, Jerking at 1600-2000 RPM

And I'll try again.

Hello fellow DIY enthusiasts,

I drive an 85 kW PD TDI Sharan (first registered 01/01, AUY engine) with a 5-speed automatic transmission. For almost two years now, VW has been trying to diagnose the problem, and they've been working on it for a year. Since I first reported the issue, I've driven over 50,000 km, and they haven't been able to fix it.

The car exhibits a strong shaking or vibration, which I'm not sure how to describe, between approximately 1,600 and 2,000 rpm. This only occurs under load, and so far I've experienced it in the 3rd, 4th, and 5th gears. In 3rd gear, it either only happens with heavy acceleration or when driving uphill (e.g., the Zirler Berg). I suspect it would also shake in 1st and 2nd gear, but the load under normal conditions is usually not sufficient to trigger it.

I've now found an interesting thread that concerns Fiat, and it describes exactly the same phenomenon as I'm experiencing with my car.

http://www.autoextrem.de/showthread.php?t=2171&page=4&pp=10

'So far, half of the car has been replaced: the automatic transmission, two drive shafts, the transmission control unit for the automatic transmission, the air conditioning compressor, and the engine mounts (suspension). Since the engine mounts were replaced, when the timing belt was renewed, the 'jerking' has become more of a 'vibration.'

I also tried to see if chip tuning would make a difference. It did, but it made it worse. In normal conditions, it's quite severe up to about 10°C, then it's a bit less up to about 15°C, and above that, it's more of a rumbling of the engine, barely noticeable. After the tuning, it was still noticeable even at higher temperatures.

Could it be possible that, for example, if the intake manifold runner is adjusted, the amount of fuel injected is insufficient for the amount of air entering, essentially lagging behind, and thus causing a lean misfire? It's true that the engine requires more fuel at lower air temperatures. The same applies if the engine is tuned; it needs more fuel earlier in the process.

I have the impression that the car, specifically in the area where it jerks, has particularly low fuel consumption values. Furthermore, it is definitely quite sluggish in the higher RPM range (above 2,000 rpm), and I experienced an oil temperature of approximately 115 to 120 °C when driving at speeds around 160 km/h, with an outside temperature of 12 to 15 °C (which is summer in Germany, you know ).

It would be great to hear the opinions of some of you on this.


First of all, best regards.

Peter.

Hi,

Let's try a different idea...

Have you checked the turbo? Your description doesn't mention it.
'I'm bringing this up because we've recently chipped two 150 HP TDI (ARL) engines, and they also vibrated under full load in the same area you mentioned. It only happened in the 4th, 5th, and 6th gears. When I went for a test drive with the programmer, I immediately thought, 'Ah, the dual-mass flywheel.' He replied, 'No, that's from the turbo.' Apparently, there were some air turbulences in the engine. He then adjusted the engine maps a bit, and the 'jerking' was reduced significantly, almost to the point of being unnoticeable.'

Maybe something similar could happen for you too?

arne

PeVe wrote:

Could it be possible that, for example, if the intake manifold runner is adjusted, the amount of fuel injected is insufficient for the amount of air entering, essentially lagging behind, and this causes a lean misfire? It's true that the engine needs more fuel at lower air temperatures. The same applies if the engine is tuned; it needs more fuel earlier in the process.

You have a diesel engine, and it's running with an excess of air .
Have you ever seen one with a throttle valve?

wolfi_b wrote:

Or have you ever seen one with a throttle valve before??

... Yes, I do! My AXR has a throttle valve. (see https://community.dieselschrauber.org/en/viewtopic.php?t=4521&highlight=drosselklappe)

The jerking starts only slightly above 1,600 rpm, which is where the turbo kicks in. So, the engine isn't naturally aspirated – I'm forcing air into it. Isn't it possible to create an excess of air in that situation?
Older VP TDI engines also start to stutter if the fuel pump doesn't deliver enough fuel.

Am I completely wrong with my assumptions?

Best regards,

Peter.

@ Peve

- No, the turbos in the current TDIs already reach boost pressures higher than 1600 kPa (or roughly 16 bar) earlier than that!

- Diesel engines ALWAYS operate with an excess of air. If they don't, the person behind the vehicle could die from carbon monoxide poisoning.

- No, the older VP37 TDI engines don't misfire because the pump delivers too little fuel, but because the injection quantity fluctuates, which the engine control unit can no longer compensate for. The key issue is a change in unknown variables within the control loop.

How do you conclude that there is "too little" fuel in relation to a diesel engine?
There is no mixture being processed here, so there can't be "too little" of anything.

If less fuel is supplied, the engine will simply run slower. Whether that's intentional is another matter.

However, the jerking motion will not stop if we assume that this amount is gradually reduced over a certain period of time.

m;

I have the impression that the car, specifically in the area where it jerks, has particularly low fuel consumption values. Furthermore, it is definitely quite sluggish in the higher RPM range (above 2,000 rpm), and I experienced an oil temperature of approximately 115 to 120 °C at speeds around 160 km/h, with an outside temperature of 12 to 15 °C .

Has the mass airflow sensor (MAF) ever been checked or, as a test, replaced with a new one? The above suggests a defect of that kind.

PeVe wrote:

Der Wagen hat ab knapp über 1.600 bis knapp über 2.000 rpm ein starkes Ruckeln oder wie man es auch immern nennen mag. Es tritt nur unter Last auf, bisher im 3., 4. und 5. Gapprox.

Hi,

That reminds me of my old VW Golf 3 VP.

With an active tuning box and full throttle from low RPM in higher gears, something would often build up to a violent "shaking" that would rattle the entire car.

If you quickly pressed the accelerator, the problem would disappear above approximately 2000 rpm.
I still don't know what it was.

Some people thought it might be a slipping clutch, but even with a slight press of the pedal until the clutch started to "really" slip, it didn't change the symptoms.

I had speculated, among other things, about potentially manipulating the ZMS, but as I said: I don't know .

I experienced a similar jerking sensation in my car, but it occurred while driving at a constant speed, not during acceleration.

Replacing the pump injectors seems to have resolved the problem.

Best regards,

Hmmmmm??

The LMM (likely referring to a mass airflow sensor) was replaced right at the beginning. As far as I know, I don't have ZMS (likely referring to a specific type of suspension or control system) in my automatic transmission.

'That's exactly the symptom. It happens on a straight road, but not at full throttle, in the higher gears. It appears at a specific torque level, and it's more noticeable when going uphill under load. On a flat surface, the lower the gear, the more I have to accelerate for it to occur.'

By the way, I also disconnected the AGR valve, but there was no change. However, while doing that, I discovered the reason for the knocking sound when the engine is turned off: the hose for the AK (Abgasrückführung) or DK (Dieselpartikelfilter) was disconnected; the workshop probably disconnected it accidentally. When I complained about this symptom, I was told that it was completely normal .

What could be the reasons for the oil temperature being so high, especially just outside of Munich, while driving very moderately, with an average fuel consumption of about 7 liters (in the city with a Sharan, 1.8L engine!!), with an air temperature of 20°C, and an oil temperature of 100°C?! Is this normal? I'm using Castrol LL 0W30 oil.

It seems this kind of stuttering is common in many modified vehicles. Has anyone been able to determine the cause yet?

Thanks for your participation in the discussion; I'm starting to get a little frustrated with this.

Best regards,

Peter.

Bertil wrote:

wolfi_b wrote: Or have you ever seen one with a throttle valve before?? ... Yes, I do! My AXR has a throttle valve. (see https://community.dieselschrauber.org/en/viewtopic.php?t=4521&highlight=drosselklappe)

Oh, I learned something again .
Although the purpose is completely different from that of a gasoline-powered vehicle.

PeVe wrote:

By the way, I also disconnected the AGR valve, but there was no change. However, while doing that, I discovered the reason for the knocking sound when the engine is turned off: the hose for the AK (Abgasrückführung) or DK (Dieselpartikelfilter) was disconnected; the workshop probably disconnected it accidentally.

When I complained about this symptom, I was told that it was completely normal.
}


... Great workshop }.

Have you ever had the pressure of the tandem pump checked? If the pressure is too low, it can cause problems with the fuel supply to the PD injectors. This can then lead to engine misfires (which is also stated in the VW PD injector manual!!).

The most complex but optimal solution was the installation of an air bypass channel: branched off before the HFM (heated fuel mixture) after the EGR (exhaust gas recirculation) valve, with the exhaust channel sealed. In principle, I replaced the EGR exhaust flow with fresh air and retained all valve and flap functions.

Hello,
How is that supposed to work? Where does one get fresh air with the same pressure as that before the turbocharger?
Regards,
perwollf

perwollf wrote:

Quote: The most complex but optimal solution was the installation of an air bypass channel: branched off before the HFM (heated manifold flange) after the EGR (exhaust gas recirculation) valve, with the exhaust channel sealed. In principle, I replaced the EGR exhaust flow with fresh air and retained all valve and flap functions. Hello, How is that supposed to work? Where does one get fresh air with the same pressure as that before the turbocharger? Regards, perwollf

Hi,

Where did you get that quote about the fresh air bypass?
I can't find anything like that in this thread.

(Your objection is, of course, correct.)

Oh, sorry, you are absolutely right!

This sentence is from Sepp, and it comes from a discussion that Rainer K. inserted as a link right before my comment.

Well, that was my first post...