Pump Replacement Due to Flow Meter Issues

Hi.
Based on the fairly clear explanation of the cause of the slight surging at partial load between 1200 and 1900 RPM, which disappears when the speed sensor connector is disconnected, I plan to replace the pump.
Since the car has only 150,000 kilometers on it and I plan to drive it for a few more years, I want to replace the pump with a new one.
Since the jerking stopped completely for me as soon as the speed signal was lost, I should be quite certain that the problem lies with the pump.
Has anyone ever had a different experience where replacing the pump didn't fix the problem, even with these exact symptoms? Unfortunately (or fortunately?), the search function hasn't found anything related to that either.
The frustrating thing is that Bosch doesn't want to take back the pump.

Regards,
Hermann.

Hi Hermann, if Bosch doesn't want to take the pump back, maybe you could give it to me?
I'd like to disassemble the pump and see what exactly is causing the jerking/stuttering.
I would cover the shipping costs.

Hi Mersenne.

Bosch is unwilling to take back the new pump unless the defect can be proven to be related to the old pump. In any case, I will only receive the new pump as a replacement.
If I have a few days to return the item, you can feel free to disassemble my old one (pump! ).
Would you also confirm the suspicion of a faulty pump if the described symptoms disappear when the speed sensor connector is disconnected (what a word...)?

Regards,
Hermann.

That's really a messed up thing.
If it were my car, I would keep driving with the sputtering until I either found a used pump or could get it repaired cheaply.

You can find them for around 100 euros on eBay.

Steffarn wrote:

This is really a fucked up thing. If it were my car, I would keep driving with the sputtering until I either found a used pump or could get it repaired cheaply.

I would also choose that option.

Well, with the pumps offered on eBay, I initially assume a similar defect; they're not being replaced for no reason. And if you then factor in potential repairs, the cost can quickly reach 700-800 euros.
If I were to get a new one for €700 (with a 30% discount; including a 2-year warranty), then this could be an alternative.
I was more interested in the question of whether the fault definitely lies with the pump, if the jerking stops when the speed governor is disconnected, or whether anyone else has had a different experience.

Regards,
Hermann.

palmstrollo wrote:

I was more interested in the question of whether the fault definitely lies with the pump if the jerking stops when the speed governor is disconnected, or whether anyone else has had a different experience.

Okay, the jerking can also be caused by other issues (e.g., genetic predisposition, injector spray pattern, DiFi, mass airflow sensor, faulty temperature sensors). However, these problems can be diagnosed easily and without difficulty. The pump itself is diagnosable, but the jerky behavior caused by the regulator cannot be detected through diagnostics.
It's unlikely that anyone will be able to give you a definitive answer. There are Bosch services that can perform what is called a "hyteres" test. This involves testing the flow meter and the control behavior. This is the only reliable way to determine if the pump (flow meter) has a defect. Unfortunately, very few Bosch service centers offer this type of testing.

There are also various pump replacement options available in this forum (including from DocSnydor), and the problem disappeared after the pump was replaced. I sold my car with that error, and the subsequent owner received the car with a different pump than the one that was originally installed. I couldn't figure out why (it was very noticeable!).

Then I suppose I'll have to contact my Bosch service center and ask them to perform a hysteresis test.

Thank you.
Hermann.

Please provide more details about WHEN your car is shaking.
Is this also applicable in continuous operation? What about during load changes? What is the required speed (RPM), etc.?
I have the same problem.
However, the cause was due to other parts - but I have still managed to eliminate the problem about 90%.
georg

"Palmstrollo already wrote when..."

Quote:

... the gentle vibration at partial load between 1200 and 1900 rpm, that...

"I'm experiencing the same issue: it's particularly annoying in the 4th and 5th gears. When driving within the speed range mentioned, i.e., maintaining a constant speed, the entire drivetrain starts to oscillate (with noticeable jolts from the gear lever, etc.). This seems to be caused by the uneven engine running or slight jerking under this load condition. It's more pronounced when the engine is cold."

It might take a long time to find a suitable ESP (Electronic Stability Program) for an early B4 TDI on eBay. And even if you do, it will likely have similar mileage. This is because the system was only installed in this specific model from mid-1992 to the end of 1993. It still uses a slider potentiometer.
Bosch part number: 0 460 404 995.
Part number: 028 130 109 J

It's exactly as faz writes.
Specifically, this happens when coasting in the 4th or 5th gear. It has NOTHING to do with load changes.
Even the gear lever starts to sway rhythmically.
The part numbers are also correct; the pump may have an additional 'X' at the end of its number.


Regards,
Hermann.

It's exactly as faz writes.
Specifically, this happens when coasting in the 4th or 5th gear. It has NOTHING to do with load changes.
Even the gear lever starts to sway rhythmically.
The part numbers are also correct; the pump may have an additional 'X' at the end of its number.


Regards,
Hermann.

Okay, mine does that too.
I've always assumed it was due to faulty motor bearings, or rather, they were definitely broken! But you already replaced them, which is strange.
But it's great to drive through the city at a speed of 60 km/h in fourth gear.
Best regards,

I still assume that this is not normal, even though three people here in the forum are experiencing the same symptom. Furthermore, when I installed a slightly more powerful chipset last week, the stuttering became SIGNIFICANTLY worse.
In my opinion, the other chipset required more of the 'anti-jerk' comfort feature, and therefore, due to the metering device not responding quickly enough, the jerking was amplified.
Correct me if I'm wrong.

Regards,
Hermann.

I also initially assumed it was related to the motor or transmission bearings.
I've replaced all the hydraulic mounts and rubber mounts on the transmission now, all at once. After 240,000 km, they were really worn out.
But the problem remains: there's still too much bouncing. It's not as severe as before (presumably because the rubber is absorbing more of it), but it's still excessive.
It must be that persistent MSW problem again.
I'm curious to see what Marcello's instructions are...

I picked up the pump yesterday. It is scheduled to be installed on Friday. In addition to the 1050 EUR for the pump, there were an extra 160 EUR for the timing belt, tensioner pulley, and idler pulley.
Hopefully, it will work properly again then.
The diesel specialist at Bosch immediately said 'quantity control unit' when I described the symptoms to him. Unfortunately, they were unable to perform a hysteresis test.

I will let you know when it's finished.

This is really a fucked up thing.
If it were my car, I would keep driving with the sputtering until I either found a used pump or could get it repaired cheaply.


I also wanted to do it this way. The problem is that the shaking just keeps getting worse... At some point, I told myself, 'That's enough,' before it shakes the whole thing apart.
'It's definitely gone since the new pump was installed. (Although I felt like it might be coming back recently, but that was something else...)'