VP37 (ALH): Get Help & Solutions Now!

Hello diesel experts, I'm having the following problem with my Golf IV, model year 2000 (ALH engine, 40,000 km):

About half a year ago, it all started with a metallic clicking sound from the fuel injectors and a muffled knocking noise from the engine – also, the performance and top speed decreased somewhat.

To put it simply - after I replaced the original fuel injectors with replacement injectors from Bosch, the clicking sound was initially gone , but the knocking was still present and the performance didn't improve - furthermore, a rather loud cold start issue developed .
After about 500 km, the clicking sound from the injectors started again (it would disappear intermittently after highway driving, but then become louder again during short trips).

After consulting with a master technician at a V.A.G. workshop, I adjusted the start of fuel injection, which he believed was too early. I tapped into the line from the injector control valve and, using a multimeter, adjusted the start of fuel injection so that the pulse width at full load is approximately 1.8 volts.
After that, the car had cold start problems (it took a long time to crank), and the knocking sound was still very strong for about 20 minutes after starting from cold.

Frustrated, I took the car to a Volkswagen dealership to have them check (as much as possible) and adjust the fuel injection pump.
After three days!! I was finally able to pick up the car. They told me that the start of the fuel pump had been set too late and that it had now been corrected.
Sure, cold starting is no longer a problem, but the fuel injection start-up timing is now set so early that the mixture control valve is almost always fully engaged (at 13 volts).
and under full load, it only briefly drops to just over 4 volts before quickly rising again - it's clear that the motor now runs roughly and idles like it's in a limp-home mode.

I'm desperate - can anyone help me?

Best regards,

Sure.

Here is the translation of the text from German to English:

'Stp' is an abbreviation for 'stop.' It is often used in programming languages and other technical contexts to indicate that a process should be halted or paused.

In some cases, 'stp' may also refer to a specific type of software or hardware component. For example, it could be the name of a particular library or driver.

If you are unsure what 'stp' means in a given context, you can always consult the documentation for that specific application or system.

Hi.

Hmm... I'm not sure if you're just hearing the sound of fleas coughing.

"My car, with almost 40,000 km on the odometer, has been making similar noises for years, and I don't worry about it anymore because practically every TDI engine doesn't sound perfectly smooth once it has a few thousand kilometers."

For me, the slight ticking sound (while it's still cold) seems to be coming more from the valve mechanism. When I turn off the ignition while going downhill (which cuts off the fuel injection), the ticking continues unchanged...

Okay: set the injection start back to its original setting - and as long as the engine doesn't sound seriously ill, just turn up the radio a little louder while driving .

Hello Ulf,

That was fast - thank you very much .

I don't know if this type of noise is normal, but since it started, the maximum speed has decreased by about 15 km/h – meaning only 180 km/h according to the speedometer (before, under the same conditions, it was around 195-200 km/h).

Well, I'll definitely reset the injection settings to the previous values and then continue monitoring.

Best regards,

Sure.

Here is the translation of the text from German to English:

'Stp' is an abbreviation for 'Stop.' It is used in various contexts, such as:

* In programming, it can be used as a command to halt the execution of a program.
* In music, it can be used as a notation to indicate a pause or break in the music.
* In general conversation, it can be used as an exclamation to express surprise or disbelief.


P.S.: The clicking sound from the nozzles is mainly audible in the lower load range (primarily the 3rd nozzle with NHG). When the thrust is reduced, the noise (which can be as loud as a faulty hydraulic lifter) disappears!

StpDiesel wrote:

I don't know if this type of noise is normal, as since it started, the maximum speed has decreased by about 15 km/h - meaning only 180 according to the speedometer (before, under the same conditions, it was about 195-200).

Hi.

I always view top speed measurements with some skepticism – sometimes you have an 8 km/h tailwind, and other times a headwind, which you may not even notice, but it can still significantly affect your perceived "performance" on the same route.

Have you ever measured the performance using the DZR (German standard for energy efficiency)?

Quote:

P.S.: The clicking sound from the nozzles is mainly heard in the lower load range (mainly the 3rd nozzle with NHG), and when the thrust is switched off, the noise (which can be as loud as a faulty hydraulic lifter) disappears!

My nozzles aren't that loud, because such a noise wouldn't disappear when the thrust is cut off...

Hello Ulf,

You're right about the differences in top speed – I'll try to assess the performance based on the data from the DZR (Data Recording Unit). Otherwise, I'll probably just go with the reel.

Oh yes, another strange thing about the nozzles is that the clicking sound after a long highway drive sometimes disappears for a while (a few days).?!?

Greetings.

Sure.

Here is the translation of the text from German to English:

'Stp' is an abbreviation for 'stop.' It is often used in programming languages and other technical contexts to indicate that a process should be halted or paused.

In some cases, 'stp' may also refer to a specific type of software or hardware component. For example, it could be the name of a particular library or driver.

If you are unsure what 'stp' means in a given context, you can always consult the documentation for that specific application or system.

Hello STP.

'I have the same car, with a 90 horsepower ALH engine, manufactured in 2001, and it has 105,000 km on the odometer. It also makes the exact same ticking sound that you're describing, since around 15,000 km. I've gotten used to it, but I still haven't been able to pinpoint the source of the noise, and I only hear it at city speeds.'

How did you manage to pinpoint the noise to the 3rd ESD using the NBF?
There are also four pressure relief valves at the outlet of the injection pump, which could potentially be a source of noise.


Best regards, Gerd.

How did you manage to pinpoint the noise to the 3rd ESD using the NBF?
There are also four pressure relief valves at the outlet of the fuel injection pump, which could potentially be a source of noise.


Hello Gerd,

It was relatively easy to pinpoint the source of the noise, as it became very loud after driving in city traffic for a while. By using a mechanic's stethoscope (I don't know the exact name of that tool) to listen to each individual nozzle (while the engine is idling), you can fairly easily determine where the noise is loudest.
It's also a pain in the neck because even with the replacement nozzles from Bosch, the problem persists.

I had also considered the pressure relief valves on the injection pump and I have already replaced one of them (the one for the 3rd injector/nozzle) – but there was no noticeable difference, except that my wallet was 30 euros lighter!

Have you already taken your car to the workshop about this problem?
And if so, what were you told about where the problem lies?


Regards,

Sure.

Here is the translation of the text from German to English:

'Stp' is an abbreviation for 'stop.' It is often used in programming languages and other technical contexts to indicate that a process should be halted or paused.

In some cases, 'stp' may also refer to a specific type of software or hardware component. For example, it could be the name of a particular library or driver.

If you are unsure what 'stp' means in a given context, you can always consult the documentation for that specific application or system.

Hi Gerd,

That sounds very much like lifters . Before I replaced them, I had quite a bit of knocking (but with 174,000 km mileage), especially in the first few minutes after a cold start, and since installing the new lifters, it runs like a kitten! But with cylinder deactivation, that noise should actually be audible as well... hmm.

Hello,

'This ticking sound was initially very faint, but it's now louder and more pronounced. It's only audible when accelerating under load, so it probably isn't a problem with the hydraulic lifters. Sometimes it's quieter, for example, after a fast drive on the highway.'
'I had complained about this issue back then during the warranty period. Someone from the regional sales center interpreted it as a 'normal injector noise' that wouldn't require repair, wouldn't affect the engine's lifespan, and forbade the workshop from attempting any repairs...that's what the service manager of the workshop later told me in confidence. He advised me to contact the manufacturer directly.'
'But he wouldn't or couldn't tell me what the cause was. He performed a compression test and pressure loss measurement back then, but everything was fine. The engine still consumes a small amount of oil (1 liter per 17,000 km).'
But it's misfiring slightly on one cylinder. But that seems to be the case with almost every TDI I hear; none of them run perfectly smoothly.
So, I'll let it run... the engine seems to be in pretty good condition otherwise.

Best regards, Gerd.

Deleted upon request.