Car Engine Failure: What to Do?

Hello,

Volkswagen Golf IV 1.9 PD.
74 kW.
MKB: AXR
BJ: 12.2001
(This likely refers to the year of manufacture: 2001, December)

"So, my car unexpectedly shut off today and wouldn't start again. Luckily, I had my computer with me, so I could immediately read the error codes. It indicated a short circuit in the mass airflow sensor. Hmm, that couldn't be right. However, I also noticed that the fuel pump wasn't making its usual sound when I turned the ignition on. So, I tapped on the pump, and after some fiddling, it started up, albeit reluctantly."
Now it's running rough, like it's on only three cylinders, and it's smoking like crazy.
I then reconnected the measuring device and read out the data blocks. While doing so, I noticed that the first cylinder had a difference of >2 mg/h compared to the other cylinders during the idle operation.
He had already had a somewhat uneven gait before, but not to this extent.

Okay, here's the translation:

Now, my questions:

Has anyone ever encountered this problem before and been able to solve it?
2. Does anyone know the fuel flow rate of my fuel pump?
3. Does a PD element *necessarily* have to be defective?
4. Can PD elements be tested?
5. Could the poor performance be due to insufficient fuel supply?
6. Can insufficient fuel supply damage the PD elements?

Thank you very much for reading, and thank you for the responses.

Hello Holzbein:
1 Question: Yes, on a Sharan. It was exactly the same issue. There was a defective PDE (Positive Displacement Element).
2. Question: I need to look up the specifications for the electric pre-feed pump. I know the performance of your tandem pump. The minimum pressure must be 7.5 bar at 4000 RPM. You'll need a pressure gauge to test it, such as a VAS 5087 or similar.
3. Question: Not necessarily.
4. Question: You can remove the valve cover and check the resistance between the two contacts on the PDE. Make sure to disconnect the connector while doing so. The resistance should be approximately 0.5 ohms. You can also check the voltage between the brown wire and ground (with the ignition on). The voltage should be approximately 0.1-0.4 volts.
You can also check if the pressure equalization device (PDE) is loose, for example, by breaking the screw of the locking wedge. Then, you can insert the PDE into a different cylinder and see if the problem moves along with it. This will help you determine the cause.
5. Question: What does MWB 23 indicate? High negative values?
6. Question: I'd like to know that too. On my Passat AJM, two high-pressure pumps (PDEs) failed along with the tandem pump. The fuel filter was only half full because the pump couldn't keep up. The AJM model didn't have an electric fuel pre-pump until model year 2035. I only bought the VAS 5087 later, so I don't know the values. After the pump was replaced, the filter was full again, and there was noticeably more power, and the engine ran much smoother and quieter. However, the PDEs were still faulty.

You could also try replacing the PDE wiring harness as a precaution. It costs 40 euros and is prone to failure.
Is MWB 18 also okay?

What exactly is the pre-charge pump?

Thank you for the answers.

The measurement block 23 should represent the idle run state. In any case, in the idle run state, the...
First cylinder: 2.99 mg/hub.
2, 3, and 4: approximately -0.99 mg per vial.

I need to check the MWB18 first.

MWB 13 refers to the idle speed control. The number 23 represents the switching times of the solenoid valve. The BIP index – you could take a quick log of values 13, 18, and 23.
Steffen.

Okay, I'll do that. It might take a while, as the car is no longer within my immediate area. I'll upload the logs once I've created them.

Here are the logs I have. How do I upload them here?

Are you looking here: /viewtopic.php?t=12997

Ah, okay. I could have figured that out myself.

Well, Wooden Leg, unfortunately, I don't have any good news for you.
Cylinder 1 is your problem. Not enough fuel. Also, read this: /viewtopic.php?t=9888&highlight=mwb+023

The negative values on the other 3 cylinders in MWB 13 indicate that the software is trying to compensate for the high addition applied to cylinder 1. The goal is to achieve approximately 0 as a net result.


First: What exactly is the issue with the electric pre-feed pump in the tank? Ensure its function and flow rate are working correctly!

You'll need to borrow or build a VAS 5087. I can tell you how to do that if you're interested. Then, as a second step, connect the diagnostic tool to the tandem pump and measure the pressure of the tandem pump.
"It requires a pressure of 7.5 bar at 4000 RPM. A rough guideline at 1500 RPM is 3 bar."

If it's not obvious, during the measurement, try pinching off the return hose at the filter and see if the value on the pressure gauge increases. If it does, you're lucky, and it's likely just the middle O-ring on the pressure sensor. This O-ring seals the connection between the supply and return lines. Fuel would then flow freely through this path.

"It might not be anything, but you should test the PDE as described above. It's best to try it in a different cylinder and see if the problem moves along with it. You might get lucky and it could be the wiring harness. This is a good way to check. Otherwise, replace the PDE cylinder 1. Be careful with the M6 screws on the tensioner. The threads in the head can strip easily. Always use new screws!"

Do you use regular diesel?
What was the status of the PDE (Positive Crankcase Ventilation) system, and were there any error codes stored in the fault memory?

holzbein wrote:

... Now it's running with a noticeable wobble, almost like it's balanced on three supports, and it's smoking excessively.

According to your log, it seems he's only active on three platforms.

Quote:

... He had already had a somewhat uneven gait before, but not to this extent. ...

With the 019 CR control unit, it's no wonder...


What's in the error memory? Just the mass airflow sensor? I can hardly believe that based on the values.

If you could send me a guide for that, it would be really great.
Based on the values in the MWB13 data, I read that if the control unit completely reduces the fuel quantity, there should be a reading of -3.01 mg/stroke.
So, I would now conclude that it is being over-fueled, which would also explain why the fuel is not being completely burned.
If I install the PD element in a different cylinder, would I need to readjust it?

I've found the pumping capacity of my pre-pump, and it should be less than 180 liters per hour. I'll test it out.

Bertl:

Unfortunately, the only error code stored is for the mass airflow sensor.


Thank you in advance for your support. Nowadays, if you don't have the manufacturer's documentation, you're completely lost.

holzbein wrote:

If I install the PD element in a different cylinder, would I need to readjust it?

Sure. But it's not a simple task. You'll need quite a few specialized tools. That's probably going to be the problem. Give me your email address, and I'll send you a guide.

Okay, we're going to do that with the VAS 5187 right now. You go to the dealer and order the hollow screw VAG 5187-1. They'll need an AZE number for that. The number is ASE 404 520 01 000.

This is a hollow screw with 10 copper rings. It fits into the test port of the tandem pump and costs around 20 euros.
Then you go to a hydraulics specialist (we call them Simpex Hydraulics) and have them sell you a fitting for the hollow screw, 0.5 meters of hose that can withstand 10 bar, and a 1/4 inch connector for a pressure gauge for the other end of the hose. And have the hydraulics specialist properly crimp the whole thing.
Don't even bother with hose clamps. They'll fly off and hit you in the face when you accelerate, along with a liter of hot diesel fuel.
Then you'll also need to buy a pressure gauge with a 1/4 inch connection. A decent one with a glycerin filling costs around 25 euros. Wrap the threads with Teflon tape, screw it in, and you've got your own tandem pump tester.
All in all, that comes to 65 euros. If you only need it once, you might be able to borrow it for cheaper if you know someone. But if you do this often, you'll be glad to have it.

Bertil thinks that you have what's called the "jerk control unit."
You need to read more about this here: /viewtopic.php?t=1726&highlight=axr+ruckeln

Log entry, Star Date 09112008.

I wanted to test the pumps today, but the vehicle won't start at all now.
We then checked the flow rate of the pre-pump. It was approximately 0.8 liters in half a minute, which is equivalent to a flow rate of about 96 liters per hour. This is about half of what it should be.

-But it should still work, right?-

We weren't able to test the tandem pump. However, we checked to see if anything was coming out of the return line. While fuel is indeed coming out, it's only a very small amount.

Then I only measured the resistance values of the P-D elements that were correct.
The 1.4V voltage reading when the ignition is on is not due to the wiring harness. Even when measuring during startup, the voltage only increases slightly.

Can anyone tell me what this is about? Or could someone measure the values on the cable harness of the PD elements and let me know? The bottom middle pin is the ground, and the other pins are the voltage supplies for the PD elements.

I'm at a loss for the moment.

You need to measure the voltage between the negative terminal of the brown wire of each cylinder and ground. The ignition must be on, but the engine should not be started. You should see a voltage between 0.1 and 0.4 volts. In my Passat, it was 0.3 volts.

I had the cover removed. The resistance values of the PD elements are correct. As mentioned, there was only 0.06V at the connectors of the PD elements on the wiring harness. Therefore, I measured at the connector before the wiring harness to see if there was the same low voltage there, and of course, there was.

We first checked the pre-filter pump and then inspected the diesel filter to see if it was clogged. However, the same 0.8 liters were flowing through.
To check the tandem pump, I first need to get the motor running again.
We want to directly fill the tandem pump now and see if it draws in the fuel.