Kaltstartproplem beim 1Z nicht gelöst *heul* | Posts 32+

haehnlein wrote:

@Bertil: If the spray pattern is altered as shown in Henzo's pictures, why is there almost no soot being produced when running at full load (0.000001)? Shouldn't that also lead to the formation of larger particles?

"... thicker particles are present, but not significantly more..."
Soot is usually caused by too much diesel fuel or not enough air. However, the amount of soot produced is primarily controlled by the ESP (Exhaust Gas Recirculation) system.
The poor spray pattern affects the type of combustion (flame front). As you can see in the picture, the old nozzle is still spraying excessively. It's even possible that the spray hits the piston or the cylinder walls, which could cause significant damage.

@DocSnydor
Ich mach dir doch keine Angst ....

Quote:

I had the new bearings and seals installed for my ESP pump at Henzo! Very competent pump specialist, I highly recommend them!!!!!!

I haven't had any experience with Henzo yet, but what he writes in various forums and what people write about him speaks highly of him!
By the way, he seems to have all the ET catalogs and nozzle combinations memorized ... or he simply knows what is written there .

Quote:

But: This weekend, my dad's new tires are being installed, and hopefully, we'll have a better idea of what's going on then.

Keep us updated...

Hi!

@Bertil:

Please don't hit me -> I can't wait for the weekend again.

If the spray pattern from my nozzles looks like the one in Henzo's photo, where does the white smoke come from? Shouldn't that be more likely to occur with new nozzles?

Today I tried to start it four times, and it started well each time, but this time a relatively dark puff of smoke came out -> that's strange.


Best regards, Christian.

haehnlein wrote:

@Bertil: Please don't hit me -> I can't wait for the weekend again.

It's alright...

Quote:

If the spray pattern from my nozzles looks like the one in Henzo's photo, where does the white smoke come from? Shouldn't that be more likely to occur with new nozzles? Today I tried to start it four times, and it started well each time, but this time a relatively dark puff of smoke came out -> that's strange.

Hmm... good question. The white smoke when starting should occur if too much diesel is burned with too little air, especially in a cold state. I think one or more injectors are dripping. It should also smell really bad. The dark cloud appears at higher combustion chamber temperatures.


Here's a completely new idea: The opening pressure of your injectors is too low, and the injectors are opening too early. Because neither the fuel injection timing device nor the quantity control system, nor the knock sensor has any effect during cold start, too much diesel is being injected. When the engine is running, the EDC (Electronic Diesel Control) can detect this problem using the knock sensor and slightly compensate for it. However, since no regulation limits are being exceeded, there is no error code stored in the diagnostic memory.If it's only one injector, the idle stabilization should indicate that using VAG COM. However, if all four injectors are behaving equally, you won't see anything.

Hi!

So, the nozzles are installed! The better spray pattern of the new nozzles was immediately noticeable due to the three times larger white smoke cloud !!!

He started up quickly, but then almost stalled for about 10 seconds, and after that everything was normal! It also preheated properly for 3-4 seconds (the interior light dimmed as well).
Es scheint sich hier um einen Montagswagen zu handeln. Die rausgebrochene OBD-Buchse lässt auch auf einige Versuche seitens VW vor meiner Zeit schließen diesen Fehler zu finden!!! Deshalb bin ich wahrscheinlich auch der 5. Bowner

I'm really at a loss now... but the VAG-COM diagnostic tool will be here soon... I wonder if it will find the problem?

At least I know that I've saved 380 euros on new nozzles (for now)! During the ride, I didn't notice any significant differences, and the nozzle tips weren't wet either!

The engine is mechanically in excellent condition...

However, there aren't many other possibilities left: ESP (Electronic Stability Program), temperature sensor, or a blocking device.

At the battery terminal, I noticed that the voltage is about 0.9 volts lower than the battery voltage (the terminal shows 11.9V while the battery reads 12.8V). If there's no gasket under the terminal that needs to be replaced, I can try installing the one my father has. However, I'm not sure how to use a torque wrench in that location (well, I guess I could use an open-end wrench and determine the tightening torque manually?).
Best regards, Christian.

haehnlein wrote:

Beim Absteller habe ich festgestellt, dass die Spannung ca. 0,9 Volt unter der Batteriespannung liegt (->Absteller 11,9 V und Batterie 12,8V).

Hi Christian,

"In my opinion, this isn't necessarily a cause for concern. Semiconductor switches like transistors always consume some voltage. Considering the low resistance of the disconnect switch (and the line resistances between the battery and the switch), a drop of about 1 volt is probably still acceptable."

Quote:

If there is no gasket under the stopper that needs to be replaced, I can next try screwing in the one from my father. However, I don't know how to use a torque wrench to get to it (well, otherwise use an open-end wrench and determine the moment).{!MARKER} Yes, I would probably do it something like that. Or take a giant socket wrench (if suitable and within reach), and trust the calibrated torque wrench

.

Hi everyone!

Okay, I'm starting to think the ESP (Electrostatic Precipitator) is malfunctioning! Two things have been observed with both the new and old nozzles in this cold weather:

Immediately after starting the engine when it's cold, it makes some unusual noises: I would describe it as a "wuhm, wuhm, wuhm" sound. This sound is slightly faster than a one-second interval (but only for the first minute).

After a cold start, if you shift into third gear at approximately 20 km/h and release the clutch without giving it any gas, the car will accelerate with good torque to around 30 km/h before going into overrun mode (engine braking).

Very strange. I seem to recall someone discussing this self-acceleration problem in the forum before (I can't find it anymore)! I hope that VAG-COM will soon provide me with a reliable diagnosis!

It's frustrating that the ESP received new bearings and seals just three weeks ago .

Best regards, Christian.

haehnlein wrote:

Wenn man nach dem Kaltstart bei ca. 20 km/h den dritten Gang einlegt und ohne Gas zu geben die Kupplung kommen lässt dann beschleunigt der Wagen mit ordentlich Drehmoment auf ca 30 km/h und geht dann auf Schubabschaltung!

Hi Christian,

This could be roughly the normal idle stabilization process. Below 900 rpm, the TDI engine automatically revs up significantly, and even in higher gears, it slightly exceeds 900 rpm during acceleration.
After that, he briefly engages the idle cutoff until the speed drops below 900 again, and so on.
"Anyway, mine does that, and I don't think it should be considered a defect."

When the engine is very cold, the idle speed is initially set slightly higher, or the automatic acceleration is more aggressive.

Question for the pump experts:
Can the VP 37 wear out in such a way that onlyat the "lowest" starter motor speed, so much diesel leaks that the "cold start" amount is no longer sufficient - but in operation, no loss of power or similar is noticeable (similar to Zwickel wear, etc.)

ulf wrote:

Question for the pump experts: Can the VP 37 wear down in such a way that onlyat the "lowest" starter motor speed, so much diesel leaks that the "cold start" amount is no longer sufficient - but in operation, no loss of power or similar is noticeable (similar to Zwickel wear, etc.)

Hi,

@ Ulf

I can't imagine that the pump is only delivering too much fuel during the cold start phase. The symptoms indicate an excess of fuel.

@Haehnlein

Now you have at least one fewer potential source of error. Even if your nozzles are no longer 100% perfect.

Quote:

Also ich glaube langsam, dass die ESP im Eimer ist!!

... might be, but it doesn't have to be. In any case, we should continue searching here.


@everyone

What happens when the fuel temperature sensor in the pump is defective?
Which temperature sensor is responsible for the cold start fuel quantity?

Bertil wrote:

@everyone What happens when the fuel temperature sensor in the pump is defective? Which temperature sensor is responsible for the cold start fuel quantity?

Hi Bertil.

When a defect is detected (--> error log entry!), a mid-range replacement value is typically used, which roughly covers most operating conditions.

According to my understanding, the engine temperature sensor is responsible for determining the amount of fuel used during cold starts.
The sensor in the pump only provides a density correction because the pump determines the injection amount based on volume, but a precise mass-based metering is required.

But how could that even be possible with a diesel engine: too much fuel and yet the engine still struggles to start when cold?

What can prevent the fuel from burning when the engine is already running?
Or could it be diesel fuel that has already accumulated as a puddle in the combustion chamber and is being expelled unburned while the engine is running?

Hi,

I also believe that the amount of fuel injected during cold starts is regulated by the engine temperature sensor, specifically the coolant temperature sensor.
The temperature sensor is located on the thick coolant hose that comes out of the cylinder head on the side. On the 1Z engine, I believe it was similar. So, there should be a sensor attached to the hose that runs forward from the cylinder head.

@Christian:
You already tried it out before, didn't you? And it worked well then, right?
So, is the cold start amount too low when the sensor is plugged in?

Hi.

Following your previous post, it started perfectly after three pre-glow attempts.
After that, the EDC, in my opinion, doesn't do anything different from what it usually does.

That makes me suspect there might be a problem with the filament again.

Okay, try this: Temporarily connect all the glow plugs together with a thick cable, and then run a cable of at least 6 mm² from that connection towards the positive terminal of the battery.
Instead of using a key to pre-heat the cable, press and hold the battery "+" button for about 4 seconds, then start.
If it starts cleanly with that, reverse the glow plug wiring harness, including the glow relay.

Hi everyone!

I now hope that tomorrow, ULF's adapter will finally be finished, and then we will definitely find the problem .

This morning, after two attempts to pre-glow, it started immediately at minus 7 degrees Celsius (old injectors), but still with small white smoke puffs, which have already become significantly smaller .

Perhaps I have another idea:

After removing the cylinder head, some oil inevitably entered the coolant system (which I later removed from the expansion tank with a cloth). Previously, there was G12 antifreeze in the system, which I then replaced.
Now I don't know exactly how the temperature sensor works (is it a resistance measurement?), but it's possible that even a small amount of oil could cause the sensor to provide incorrect readings? Also, the original G12 coolant isn't being used, which might also affect the values.
But at least the seemingly improved starting behavior could be related to the oil?
If the temperature sensor provides excessively high readings, then the preheating time would be too short and the fuel injection amount would be too low, leading to unburned fuel? I also can't really imagine how there could be excessive amounts of fuel.

-> This is just speculation and will soon be resolved using a diagnostic tool!

It's strange (or maybe not ), but I've already driven 900 km with this tank of gas (it's my first time filling up this car, and it holds 70 liters), and there are still over 30 liters left. But I should also mention that I am an extremely economical driver->I get new brake pads on the rear every time I go for a TÜV inspection .

Given that everything else seems to be messed up with this car, I wouldn't be surprised if the fuel gauge is also giving incorrect readings!

But still, thank you again for all the effort you're putting in!

Best regards, Christian.

Hi!

Jo: Three posts at the same time with similar speculations!!!

@ Ulf
The glow plug relay could also be faulty... I really like the idea of using a direct cable -> hopefully I'll have time this week, and then I'll give it a try!

Does the TDI engine actually continue to glow even after starting? As far as I know, older diesel engines used to glow for a few minutes to reduce the amount of blue smoke. That could be a reason for the puffs of smoke during the first minute after a cold start .

Best regards, Christian.

At least the car starts well after a long preheating period (at least 2 times and out), but then it smokes for a while!

Then it's probably a combination of incorrect afterglow time (if applicable for the TDI engine) and insufficient fuel -> temperature sensor?

Best regards, Christian.

ulf wrote:

Oder soll das Diesel sein, der schon als Pfütze in der Brennnmulde gestanden hat und bei laufendem Motor unverbrannt rausgerotzt wird?

... that's how I see it...

Haehnlein wrote:

Then it's probably a combination of incorrect afterglow time (if applicable for the TDI engine) and insufficient fuel -> temperature sensor?!

"Yes, the TDI glow plugs activate, but only until the engine exceeds 2500 RPM for the first time, or after a certain amount of time has passed..."

Haehnlein wrote:

...es könnte doch möglich sein, dass durch das Öl (es war nur ein bisschen) der Geber dann doch falsche Werte liefert????...

"...so much oil can't be in the coolant. However, the sensor should still provide accurate readings when immersed in oil."

Ulf wrote:

Für die Kaltstartmenge ist IMO der Motortemp.geber zuständig.

"I think so too, but I'm not entirely sure about that."

Hi!

How is it possible that my (AHF - assuming this refers to a specific vehicle or engine type) also starts immediately at around 0 degrees Celsius, even WITHOUT pre-glow, i.e., by turning the key in one smooth motion?

Best regards,
Uwe