VP37: efi 715 - Fuel regulation

Hi.

I'm having a problem with my 5-cylinder TDI engine equipped with a VP37 injection pump. The check engine light briefly illuminated, and when I scanned it, the error code EFI715 appeared 32 times.

Here's what I found in the information section:


Fuel regulation.


Weder Fehlercode EFI-122 Steuergerät Referenzspannung noch EFI-716 Kraftstoffmenge sollte gespeichert werden wenn die Prüfung, die den Fehlercode EFI-715 Kraftstoffregelung auslöst, durchgeführt wird. Zusätzlich muß die Motordrehzahl niedriger als 1014 U/min sein und das Signal vom Positionssensor des Kraftstoffreglers muß größer als 1,05 V sein. Diese Prüfung bedeutet, daß der gewünschte Signalwert des Positionssensors und der wirkliche Signalwert des Positionssensors verglichen werden. FehleThe EFI-715 fuel control system stores the value when the difference is too large.
Replacement value.
Fuel quantity is too high:
Turn off the fuel using the fuel shut-off valve.
Deactivated fuel regulator.
Fuel level is too low:
Sure. Please provide the text you would like me to translate from German to English.

Most likely cause.
Short circuit in the ground or supply voltage of the fuel injector's signal cable.
Power interruption in the fuel regulator: signal or power cable.
Faulty fuel injection pump.

Error symptoms.
Engine shuts off.
The engine won't start.


The error is difficult to reproduce. And, what's almost worse – I don't understand it. Is the problem in the metering unit, or... WHAT is the fuel regulator?

Perhaps someone can help me brainstorm. Right now, the car won't start at all. I was still able to dynamically check the pump settings, and so far everything seems okay there. The question is, what should I do next? I have everything here, including the pump, but I don't want to go through a whole series of replacements. Could it be something else entirely, like the wiring? Or does the NHG (presumably referring to a specific component or setting) play a role here?
Alternatively, there's also a solenoid valve for the fuel injector control; perhaps that's defective? If the car were running, I could adjust it and check if it works using a computer.

Perhaps someone here has a tip for me.

Sure, here's the translation:

"Thank you."
Hello.

Eines noch, ich bin zwar davon überzeugt, dass da kein Zusammenhang besteht - der Fehler trat aber genau 10km nach der Reparatur der Lichtmaschine auf. Die war kaputt, bin dann ohne Lima (mit zwei Batterien) bis heim gefahren, Lichtmaschine raus - neue Schleifringe, Lager, Kohlen - Lima läd wieder. Just 10km danach war der Fehler das erste mal - die Kiste fuhr dann aber wieder, ruckelte mal kurz am Stand. Then the error was no longer reproducible, and now it won't start anymore...

Sure, here's the translation:

"Thank you."

Hello.

Hi there,
EFI 715 = Fuel regulation - This likely indicates a fault related to the fuel quantity control valve or slide, possibly corresponding to VW code 00765.
You wrote that you were able to dynamically check the pump settings, so I assume you can also read out measurement data blocks.
Check what's displayed in diagnostic trouble codes (DTC) 1 and 19 when the ignition is turned on.
Happy New Year!
Herbert.

Hello.

Thank you for the tip.

Now, the car wouldn't start at all, and it was displaying the error code EFI 716.

Code:

Kraftstoffmenge, Signal Eine Prüfung für Abweichungen in den maximalen und minimalen Kraftstoffmengen. Dies wird mit eingeschalteter Zündung durchgeführt. Das Motorsteuergerät schaltet den Kraftstoffregler zuerst in seine maximale Stellung und anschließend in seine minimale Stellung. Wenn das Motorsteuergerät annimmt, daß der Kraftstoffregler eine Grenzposition erreicht hat, überprüft es das Signal vom Positionssensor. Fehlercode EFI-716 Kraftstoffsmenge wird gespeichert, wenn das Signal vom Positionssensor zu weit vom gewünschten Wert abweicht.

We somehow managed to get it running, but it was jerky and sputtering. Then we pulled the smaller connector, which caused an "EFI 714 & 173" error – indicating a problem with the shut-off valve and fuel injector. It makes sense that those two components are connected to the smaller connector.
Then I somehow managed to dislodge the main connector from underneath the vacuum pump. When I touched it, I immediately noticed that the engine started running normally. So, it seems there was a faulty connection at the connector or cable. This would also explain the direct link to the generator repair – you're obviously working very close to those cables during that process. I cleaned the connector, and now it's running normally again.A silly mistake that can unfortunately happen again. It should also be noted that the cables don't look as fresh as they should; the pump was leaking for a while, and the fuel has damaged the cables quite a bit. If this error occurs again, there will be no other option than to replace or repair the entire wiring harness, but that's not a major issue.

Thank you for your help.
best regards, uwe

Is one or both of the tension springs in the point machine broken?

Okay, remove the cover (not the MSW unit) from the pump and check if the MSW is set to zero flow or if it's being held at zero flow by sufficient spring force.

Hi.

Thank you for the tip.

IF the car is currently running relatively smoothly and these errors only occur sporadically (currently being monitored), I would almost rule that out. A mechanical defect in the spring should then cause persistent problems, right?

I strongly suspect a wiring problem. The question is whether it's inside the flow meter itself or externally (e.g., at a connector). Nothing has been done on the pump yet, such as soldering or disassembly of the flow meter.

Sure, here's the translation:

"Thank you."
Hello.

Both are possible: a wiring issue or a mechanical defect.

Since controlling the flow rate requires a feedback loop, it might still function reasonably well even with damaged springs (most of the time).

Okay, thanks. That's a nasty mistake. If nothing else works, we'll have to take the pump out. I don't think it's a good idea to just replace the flow meter alone; I doubt we'll ever be able to get it properly adjusted that way.
Currently under observation, thank you for your help!

best regards, uwe

Quote:

Da die Ansteuerung des Mengenstellwerks ein Regelkreis ist, könnte dieser auch mit beschädigten Federn noch halbwegs klarkommen (meistens).

In our case (with the five-cylinder engine in the LT), it ran a bit strangely (idle speed control) until the second spring broke.

vwSchrauber wrote:

Quote: Da die Ansteuerung des Mengenstellwerks ein Regelkreis ist, könnte dieser auch mit beschädigten Federn noch halbwegs klarkommen (meistens). In our case (the five-cylinder engine in the LT), it ran a little strangely (idle speed control) until the second spring broke.

Yes, but then it would be a constant issue, right? Not like in this case, which is very infrequent. And I drove about 25 km, and the car was working perfectly fine as usual...

During the dyno test, I noticed that the low-load fuel injection timing seemed a bit too retarded when relieving load on the engine. It was almost as if excessively large injectors were installed on a VE TDI and not properly accounted for in the software.

Quote:

Dann hab ich irgendwie unter der Unterdruckpumpe den Hauptstecker rausgefrimmelt, beim Angreifen merkte ich schon, dass auf einmal der Motor ganz normal lief. Also anscheinend ein Kontaktfehler am Stecker oder Kabel - das würde auch einen unmittelbaren Zusammenhang mit der Reparatur des Generators erklären - da ist man natürlich ganz in der Nähe der Kabel dran. Stecker mal gereinigt, nun läuft er wieder ganz normal.

Sieht so aus, als sei das Problem behoben....
hg
Herbert.

Hello.

Thanks - yes, the problem has been fixed. Or rather, it hasn't occurred again since then.

Thank you for the tips.

best regards, uwe

Hi, I also have an 850 TDI here right now that's experiencing the same problem described above.
"It also displays EFI-715, but in addition, it shows EFI-716, which indicates the quantity setting or position sensor (minimum-maximum limit deviation)."

"Recently, the pump was replaced in two workshops, and later the filter was changed and the timing was adjusted. However, it stalled again today, just like it did before those changes."

Rarely, but sometimes, you can spot bubbles in the supply line. That's why I have a question for you:
Kann Luft in der Pumpe denn überhaupt so einen Positionsfehler des Mengenstellwerks verursachen? Sollwert kommt vom Kennfeld im STG, Istwert gibt der Positionssensor aus -> kann Luft am Schieber das Mengenstellwerk so verschieben, dass der Fehler kommt? (Das STG schaltet den Motor ab, wenn zu große Abweichung erkannt wird, bei zu kleiner läßt es ihn laufen) Ich denke immer, bissl Luft geht eh gleich nach oben in den Rücklauf weg... Er It also shakes until you properly introduce air into the filter.

I've already disconnected the 8-pin connector on the pump, and pin 5 (flow control unit) seemed slightly bent... let's see if that was the problem.
Otherwise, my next step would be to look for leaks all the way down to the tank.
"Hey roorback, you know the 850 well, right? Is there a filter or something in the tank that could get clogged or leak?"

Hi.

The pump unit in the tank has the Volvo part number: 9202437.

I found a picture.

http://goo.gl/CJs7Uo

I think I've held something like that before, and as far as I remember and as you can see at the bottom of the picture, there seems to be some kind of pouch or bag attached to it, similar to a tea bag.

From time to time, there are various maintenance issues and clogged fuel filters – which indicate other problems. I wouldn't expect these specific errors to occur.

The issue with the car I repaired back then disappeared after cleaning the connectors. It has never happened again.


Best regards,