Förderbeginn springt herum bei VP37 im VW T4 ACV | Posts 16+

Hello Herbert,

FB-Target is constant.
The pump was tested on a special VP37 test bench. According to the workshop manager, it is functioning perfectly. I suspect that the tensioner pulley for the main timing belt might be too loose, and perhaps vibrations are causing the N108 to try to compensate, which then puts the camshaft into an unfavorable resonant frequency. In operation, the bus actually runs perfectly. Doesn't overdo the nail polish.
The timing belt is due for replacement in 5000 km anyway, so I can rule that out as the cause.

The story continues.
After picking up the vehicle, it was discovered that the pump start was much too early. The flow rate control was set to a higher output, which is incompatible with the chip. The front bumper was scratched due to the air conditioning condenser hanging down, and the screws on the engine cover were not tightened. And now, the kicker!
700 kilometers from home, the girlfriend had a breakdown. After 2 hours on the shoulder of the road, the car was towed to a VW workshop. The diagnosis: the wiring was fine, but the quantity control system was defective. So, I called the "Pump Expert" and asked if they could do anything about the sealing and cleaning of the flow meter. "No, absolutely not!"
The VW mechanic who now had the car said he doubted that a pump overhaul would fix the problem, as it was still dripping. "No way, that can't be!" "It must be leaking!" In German: "It can't be that it's leaking, because we sealed it."
Okay... Thankfully, there was no replacement pump available from VW. That would have cost €2500. The Touring Club provided a loan car and arranged for the bus to be towed home. We actually had the pump sent in for an overhaul to prevent a breakdown, but with an old car, things can always happen. So, I bought a new turnout for my model railway because I always want to be on the safe side.
When the bus finally arrived after 10 days, I started the replacement. I removed the old metering unit. In the process, I discovered that one of the four screws was completely loose!! The surface where the seal sits was corroded and dirty! Briefly, I removed the black plastic on the right side and...
"Believe it or not, a loose pin is actually mocking me. Not even a trace of solder was found. Furthermore, the contacts should not be soldered together under tension." Even bending the connectors cleared the error memory and caused the quantity control to malfunction when the ignition was turned on.
What else can you say? You take your car to a fuel pump specialist and pay €900 for a sealing and cleaning service to avoid breakdowns, and then you end up with a scratched car and a leaky pump that breaks down after just one month and 2000 kilometers. In addition to all the stress and the danger on the highway, there were also extra costs that could have reached almost 3,000 euros.
Basically, I could have repaired all of that myself, done a better job, and saved a significant amount of money.
Okay: The pin was soldered in place, the cover was put on, and with the first turn of the key, it was working again .
Conclusion: Do everything yourself!
Now I'm arguing with the guy who wants to make improvements, but doesn't want to talk about costs .
He was lucky, though, because the costs could have turned out to be much higher for him.
Are there any words left to say?

Very annoying, but now the car is working again, well done.

For the work on the ESP, there are specialized articles here. It also happens to me sometimes that I outsource work to relieve myself, and I might later regret it...

For readers interested in this topic, here are some relevant links:
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Best regards, Rainer.

Thank you for the links! While I have you on the line, may I ask you something?
Specifically, is there a way to reposition the quantity control valve after disassembly to its exact original position? I've always marked the pump to ensure I could achieve the same performance and starting behavior as before. The mechanic told me that the engine initially started poorly and had less power, and then it started misfiring, which resulted in negative consequences for me, such as rough idling when the engine wasn't yet at operating temperature and increased exhaust smoke.
Can a pump specialist not adjust this precisely using a measuring device or VCDS?

Thank you!

Tagessuppe wrote:

Thank you for the links! While I have you on the line, may I ask you something? Specifically, is there a way to reposition the quantity control valve after disassembly to its exact original position? I've always marked the pump to ensure I could achieve the same performance and starting behavior as before. The mechanic told me that the engine initially started poorly and had less power, and then it started misfiring, which resulted in negative consequences for me, such as rough idling when the engine wasn't yet at operating temperature and increased exhaust smoke. Can a pump specialist not adjust this precisely using a measuring device or VCDS? Thank you!

Hi,

Sure, you can configure it exactly as before, see /viewtopic.php?t=5517.

Making a "baseline" mark is still useful, as the quantity control mechanism is quite sensitive to positional changes.
You can also adjust it so that, with a warm engine and the air conditioning off, the injection amount at idle is 3-4 mg/hour.

Best regards, Rainer.

Hello,

I'm having the same problem. What was the solution?

Best regards, René.

Is the car running properly?

rene-caddy wrote:

Hello, I'm having the same problem. What was the solution? Greetings René

No solution yet. According to VCDS, the start of boost is jumping.
The engine is running normally.