Warmstartproblem der anderen Art (GELÖST) | Posts 24+

Hello,

DieselBär30x wrote:

@Uli: But the original poster isn't being rude.

That wasn't the question, but rather whether, in addition to an error message, a limp mode or other emergency procedures are triggered when the coolant temperature is manipulated. In this context, I showed a possibility of how to even prevent the error from being logged: The engine control unit (ECU) accepts the reading if the fuel temperature doesn't deviate significantly from the coolant temperature (and I mentioned where I got that information).

Best regards, Uli.

Guys, I don't have that problem. I can tell/hear when I start the engine whether it starts cleanly, doesn't start at all, or sputters because it's cold and one or more glow plugs haven't preheated. In the latter case, after a few revolutions and a little gas, it catches (and I take care of the glow plug system ).
In a diesel engine with a properly functioning fuel system, I would expect it to start running on its own after a few successful ignition cycles. The reason why the manufacturer included a minimum speed threshold for this is something I don't understand (it might be necessary for PD or CR engines).
A state between (1) = normal idling after starting, and (2) = not starting, where the engine runs roughly and can only be exited by turning it off, remains for me an unacceptable technical issue. A vehicle must be user-friendly to this extent. No operator of a machine, an airplane, or anything else would accept such an operating state.If the manufacturer had dared to address this issue in their instruction manual, they would have received a corresponding reaction from experts in the field.
hg
Herbert.

Hello fellow enthusiasts,

Here's the original poster chiming in again!

@Herbert: Du sprichst mir aus der Seele!

@DieselBär30X: Thanks for the link! But I would never have come up with the search term 'starter motor speed'...

And now, let's get to the facts:
Starting point: Engine warm (coolant temperature: 83.4°C), multi-connector disconnected from the ESP, starter motor activated multiple times for approximately 5 to 10 seconds each time.
Engine speed: The VCDS display fluctuates between 168, 210, and 252 RPM, with 210 being displayed most frequently. Therefore, I estimate the engine speed to be approximately 210 RPM.
Battery voltage: 11.0 V (measured directly at the battery terminals).
Starter current: approximately 160 A (initial value approximately 250 A).
This results in an approximate power consumption of 1.8 kW.

When you unplug the coolant temperature sensor, the engine starts much more readily and has a brief over-rev up to approximately 1500 RPM.
That's probably the discussed increase in starting fuel volume when the engine is cold, right?

Conclusion: Starter motor speed is too low, power consumption is normal (so no transition resistances) --> New starter motor ?

EDIT: Minimum speed: 300 RPM???

The prices are not cheap: AUDI: €320 (Austria), BOSCH: €245 (Austria).

Does anyone have a better source for an original quality starter motor with part number 068 911 024 F?

Best regards, Oldi.

Servus Oldi!

I had been searching for "500" and not anything else .

I would say that 210 RPM is a bit low, and something above 250/260/270 would be better.
As discussed throughout these pages, you now have the choice of buying something decent ("cheap" is NOT "affordable"!!!) or, alternatively, living with a 1-second longer warm-up time.
If you use cheap materials here, it might seem promising for a few months, but then it will likely become even more disappointing later... Decide for yourself whether you want to pay twice, get frustrated 15 times more, or do it right the first time .

You already know my advice on this. And if the coal absolutely has to be removed, I would suggest starting with the battery – it's a "cheaper" option and also more likely to work consistently.

Best regards from Munich!

Hi DieselBär30x,

How do I start with the battery???
It still has a healthy charge at 160 amps and 11.0 volts, and it's delivering the 1.8 kW specified in the starter motor specifications with 'clockwise' rotation.
I replaced this battery (of course, it's another good MOLL...) only about 3 years ago, and even then, this warm start problem already existed. With the new battery, it was only marginally better because the old MOLL battery was simply dead.

But regarding the starter motor: I certainly don't want to install just any cheap, low-quality part in my otherwise reliable Audi (so definitely no cheap, new parts). I clearly distinguish between 'affordable' and 'cheap.'
Either have Bosch/Audi replace the starter motor, or do it yourself, including removing the collector ring and rebuilding the starter.
I already have the high-temperature grease you mentioned (PLASTILUBE, which is also used on the back of brake pads).

Best regards, Oldi.

I've always been very impressed with MOLL products, and 3 years isn't that old.
However, it definitely makes a difference whether the battery fails at 11.0V or just 11.4V.

Okay, then get a starter motor from Bosch (still ask around with the dealers, maybe someone already has one in stock and would rather get rid of it than have someone else order it...). Or make it yourself.

Best regards from Munich!

I could get you a new Bosch starter for €170 plus a deposit of €60 .

Quote:

I have already used the high-temperature grease you mentioned (PLASTILUBE, which is also used for the back of brake pads)

.
That's not it. The grease shouldn't only be temperature-resistant, but also allow the bearings, etc. to run easily.
hg
Herbert.

Hi Herbert,


That's not it. The grease shouldn't only be temperature-resistant, but also allow the bearings, etc. to run easily.
hg
Herbert.

Thank you for the tip.

Best regards, Oldi.

Hello fellow enthusiasts,

My problem is solved!

I got a used starter motor from a car dismantler for 50€ and installed it.
I specifically chose the 2.0 kW starter motor from VALEO (Valeo part number D7R33, VW part number 068 911 024 E) (factory equipment: 068 911 024 C).
But be aware: I believe that this number also includes the slightly weaker BOSCH versions with 1.8 kW.

With this part installed, the engine is almost unrecognizable. It also starts up very quickly, even when it's already warm!
Der ehemalige, etwas asthmatische Klangeindruck ist einem fast düsentriebähnlichem Geräusch gewichen...
The new or used starter motor spins up so quickly that the effect I described earlier cannot be reproduced if the engine is started for too short a time (resulting in a rough running condition at 500 RPM).

I will provide the exact data (starting speed with a warm engine, current, and voltage) later.

Best regards, Oldi.

Thank you for the problem-solving!

You're welcome!

If someone is already helping you for free, the explanation of the solution should be a given.

Only in this way can other 'diesel mechanics' benefit from it!

Best regards, Oldi.

Quote:

Die genauen Daten (Start-Drehzahl bei warmem Motor, Strom und Spannung) werde ich noch nachliefern.

Okay. With that, you would have a speed at which it should reasonably start up.

EDIT: Afterwards, we'll wrap things up here.

Hello fellow enthusiasts,

Here are the promised values with the newly installed (used) starter motor 068 911 024 E (VALEO D7R33, 2.0 kW):

Starting speed:
It fluctuates between 210, 252, 294, and 315 RPM, with 252 RPM and 294 RPM being the most frequent values. Therefore, I estimate it to be around 270 RPM.

Performance:
10.7 volts and approximately 195 amps result in roughly 2.1 kilowatts.

The difference in starting behavior at 210 RPM versus 270 RPM is significant!
In my case, the exchange of ignition coils was definitely worth it.

Of course, for good starting performance, the cables and connection points must be in perfect condition (and don't forget the battery and the ground connection).

By measuring voltage and current (assuming a relatively accurate clamp meter is used...), it is possible to make an assessment of the electrical system in advance (without having to loosen any screws ).
With a power consumption of approximately 1.8 kW and a starter motor with a capacity of 1.8 kW, the wiring and battery are definitely fine!

Best regards, Oldi.

Servus Oldi!

Auch von mir einen herzlichen Dank für Deine Auflösung!!

Allzeit gute Fahrt!

Best regards from Munich!