3.0 TDI Cold Start Problems

Hello everyone!
I hope you can help me. I drive an Audi A4 3.0 TDI Quattro DPF with engine code BKN.
The car was first registered in June 2005 and has only 29,000 kilometers (approximately 17,900 miles) on the odometer. I'm very happy with the car.
satisfied. Now I have a problem: after about one day, the car doesn't work the same.
"The engine starts, but the starter motor runs for 2-3 seconds before the engine actually starts. Is there something wrong with the vehicle?"
Shortly after, it turns off again and restarts. It seems to be working now. I thought it might be...
"However, the problem is likely related to the glow plugs, but the error memory is empty. There are no visible leaks on the exterior of the engine, and there is no noticeable diesel smell. Regarding the issues with the injectors..."
I've heard about that engine before, but I doubt it would have those issues with that mileage.
defective! Who knows this problem? Can this be fixed, or is this behavior unavoidable?
normal? I would be grateful for any help.

tommi wrote:

External leaks on the engine or the smell of diesel cannot be detected.

"If air gets into the fuel system, it doesn't necessarily have to cause a diesel smell. Is there a clear fuel line in the supply side? Could air bubbles be entering there, especially during startup? (Observe the process with someone else during startup)."

Regards,
Guste.

Hello!

Okay, I haven't been able to see any air bubbles when starting.
Does the fuel pump not need to briefly run when I turn on the ignition to build up pressure?

hello tommi,

Has the fuel filter ever been changed on this vehicle?

If that's the case, please check the hoses on the filter. Has one of them possibly been shortened after the fact (e.g., using a side cutter)?
Unfortunately, it sometimes happens that the hoses are very tightly attached to the filter. If you then use the wrong tool, the fuel hoses can tear.
If you shorten them, they tend to draw in air.

(even though some people might disagree with me).

Carefully spray the hoses near the fuel filter with brake cleaner while the engine is running. If the engine speed increases, it's likely drawing air from that area.

Hello, screw-loving friend!

According to the service booklet, the vehicle has only had one inspection so far, and that was at...
21,000 km. The fuel filter was not changed there. It should be replaced at 60,000 km according to the schedule.
Maintenance plan. Maybe I should change it anyway, due to its age .
Kann nicht eventuell auch das Raildruckregelventil defekt sein? I'm familiar with that from...
Mercedes. Those things often break down there.

NO...

Don't start randomly replacing parts; that's not a solution. You need to figure out if air is entering the diesel line. The easiest way to check this is by using a transparent hose. Finding leaks can be tedious. I would start with the basic checks, even though it's a relatively new car; you won't even get your hands dirty. If you can park overnight on a fairly steep hill, with the fuel tank as high as possible relative to the engine, observe the starting behavior.

Otherwise, check all the clamps and take a look underneath the car, as it might be damage caused by debris on the road... you never know.

Before you invest any money, start by eliminating potential problems. Otherwise, you'll just waste money unnecessarily.

Okay, I will. That valve isn't exactly cheap, either!
Here's the translation:

"To reiterate the question: Does an auxiliary pump supply diesel fuel to the high-pressure pump?"
When should it start? I have a fuel pump error (code K...) according to the actuator diagnosis.
targeted, and you can clearly hear it! Or is it just an inline pump?
to equalize the liquid level in the KS container.

Best, tommi.

Quote:

Or is that just an inline pump? to equalize the liquid level in the KS container.

Pull the hose (usually with a plug/quick connector) from the fuel tank sender or in the engine compartment. Briefly turn on the ignition and check if diesel flows out.

Alternatively, as mentioned before: Connect a transparent hose to the diesel return line of the common rail high-pressure pump and check if air is coming out (immediately after connecting the hose, a small amount of air will naturally be present).
Reason: There are and have been (e.g., in PSA applications) CR high-pressure pumps with a gear pre-charge pump attached. When checking the return flow for air, you can also determine if there is a leak in, for example, a flange gasket, a hose connection, or a shaft seal.

I just tested the fuel pump function again.
She's supplying diesel to the high-pressure pump, but it's not starting up properly.
ich nur zündung an mach,erst wenn der Motor läuft! MIt sounds good.
wenn man den Motor ausschaltet läuft sie noch kurz nach! Must it?
Is that so?

Hi,

Have you also checked the displayed coolant temperature in the engine control unit before the problem occurred? Measurement block 7 might be the relevant one.

Best regards, Rainer.

Good evening.

@Rainer. Yes, I've compared all the temperature values. That was the first thing I suspected.
had. The difference in the values is approximately 1 degree, so that should be correct.
I took another look at the KS filter and the clamps. No one has been there before.
What has been shortened or altered? Everything should remain original.

"I would suggest, in your situation, checking the actual values to see how the rail pressure behaves during a cold start; it should increase rapidly. If that's the case, the injection system is likely fine. Then it might be the glow plug system. I recently had a similar case at work where the cable (terminal 30) on the glow plug relay was highly resistant. You can easily check this by measuring the voltage at the glow plug with the engine cold; it should be at least 10 volts. Just turn on the ignition and measure."
I don't know if it still works on the new car, but you could try extending the preheating time.


Best regards, Thomsch.

Quote:

You can easily check this by measuring the voltage at the glow plug with a cold engine; it must be at least 10 volts. Simply turn on the ignition and measure.

With the mild temperatures we are currently experiencing, a TDI engine should start without needing to be glowed.

Here's how we do it in the workshop: Remove the coolant temperature sensor (CTS), connect it. Use alligator clips to connect a suitable resistor, and monitor the coolant temperature using VCDS. (You can't just disconnect the CTS on the "newer" TDIs; they'll then use the fuel temperature as a substitute value.)

Turn the ignition on and check if all the spark plugs are glowing.
Caution: Maintain a safe distance between candles and plastic parts, and do not touch the candles immediately afterward with your fingers (they are hot). Also, do not repeat the game too often, otherwise the connectors may melt .

This method has the significant advantage that it also reveals transition resistances at connectors or old cables (caused by damage from animals like martens and corrosion from road salt).

Hello everyone!

A few days ago, I replaced the fuel filter for the first time, and instead of...
I replaced the hose clamps with new screw clamps. I've now checked everything again carefully.
I've checked to see how it performs. So, if the car is driven over a longer distance...
approximately 80 km have been driven, so the engine is at operating temperature, and then it is turned off and after...
After approximately 12 hours, the engine started again, but with a delay, and then it ran.
on the cylinders, and evenly, without any smoking or anything like that!
Am I not warming up the car properly, or am I only driving short distances and then letting it sit for a long time?
If it is turned off and wants to restart, it immediately starts }.

Should the glow plugs also be monitored in the 3.0 TDI engine?

At least, that's what J179 suggests.

m;

Yep! Glow plugs have a self-diagnostic function. So, it probably shouldn't be related to that.