TDI Injector Wiring Loom.......

Can anybody explain why the injector wiring looms on modern TDI's cause problems?
The reason i ask is because i removed mine after VAGVOM/VCDS came up with the following......

1 Fault Found:
18074 - PD Unit Injector; Cylinder 1 (N240): Electrical Malfunction
P1666 - 35-00 - -

Closer inspection of the wiring doesn't appear to show any damage.Resistance check also appears fine.

Thanks in advance
djl

Did you replace the wiring loom? And did this cure the problem?

or are you still in the troubleshooting phase?

Dan

What that code probably means is that your ECM did not see the current profile it expected from that injector.

The problem could be:
Bad ground at the ECM or the engine. (would include those under the battery, as well as from transmission to frame/battery.)
Bad ground inside the valve cover, where all 4 injector grounds are connected together.
Bad conductor contact on the engine or the ECM.
Broken conductor.
Bad insulation, allowing a short to the ground on that cylinder's wiring.
Bad solenoid in the injector.

Dan

By the way, I was not aware of this being a common problem. I don't think I have run across it in these forums.

Dan

Awaiting a new loom from my local main dealer which should arrive in a couple of days.
When i said it was a common problem i should clarify that is info i was given by a reputable indy mechanic here in the uk.His words were "99% of the time" it's the wiring loom.That's in relation to the code i got which commonly is on no.1 injector.
For £40 it seems a no brainer when you consider how expensive injectors are.
I will however trace the wiring and check for any problems.
My question though,if there is a earth problem surely it would affect all injectors not just the one.
Thanks for your help
djl

The four injectors are tied to a common earth inside the head (if I am interpreting the Bentley correctly). A single injector ground can pull loose, break, etc.

You can get the same code/signal if the live wire is open circuited also.

Dan

Picked up new loom from dealer this morning and had it fitted in an hour.
Have since taken car on a 30 mile trip and touch wood all appears to be fine.
I have noticed a small leak from around the tandem pump so that'll be the next job.
djl

Was this causing operational problems?

Or was this a code that came up once? Twice?

It sounds as if you have found the problem.

Good Luck,

Dan

I was hearing that the problem is the clamping of the connectors was a bit flakey and people have just pinched the connectors to get them to fit.

Problem first appeared last thursday night on way home from work.Car lost power and sounded as though it was running on 2 cylinders (engine is a 3 cyl tdi pd eng code AMF,not available in US i believe).
If car was allowed to cool down and then restarted it would run fine until engine was up to temp before giving the same problem again.Code would erase from ecu but would appear soon after engine was started.
Reading through some of the uk forums it became apparent to me that it would most likely be the harness or if not then the injector.With the harness being less than £44 it seemed a good place to start.
Fault code hasn't re-appeared as yet but i'm hoping that the issue is resolved.
djl

While vibration issues has caused fretting and wearing through of insulation, and even conductors in some cases, the main problems that I have read about were connections, as whitedog says.

You might ensure that your ECM/ECU area is staying dry, or at least draining well, and be ready to clean the electrical contacts on your connectors. Perhaps pinch them back into shape, if the problem shows up again.

Good luck,
Dan

Thanks.
I did check all the wiring and all plugs were connected securely so who knows...maybe internal breakdown.Would not surprise me as the loom is subject to heat oil & vibration like you say.
Will keep an eye on things more closely in future as car currently has 161000 miles on it and starting to require more tlc.
Djl

Hi! I think I have fuel injector problems on my 2006 Bug. And I've got some evidence that it is electrical in nature and not mechanical. Originally I thought I had gotten a bad tank of fuel (with water in it). But I deliberately ran the car out of fuel just to minimize how much water could be in the tank and I've gone through several tanks of fuel since then. The problem with the motor missing is getting worse.

I've got the same error messages as given at the start of the thread:

18074 - PD Unit Injector; Cylinder 1 (N240): Electrical Malfunction
P1666 - 000 - -
16685 - Cylinder 1: Misfire Detected
P0301 - 000 - -

Click to expand...

I checked the conductivity of all 4 fuel injectors from the big round connector on the valve cover but everything looked normal. Unfortunately, the problem comes and goes so that check may not mean anything. I also spliced into the signals at that big round connector at the valve cover. I did that non-destructively so nothing was damaged. I was able to watch the signals from inside the car while driving. When the car starts missing, the signal on fuel injector #1 looks different than the other fuel injectors. So... that is probably confirmation that it really is a problem with the #1 injector.

My question is: "Are there nice, detailed instructions for removing the valve cover?" I'm hoping to find something to guide me so I don't have to just tear into it. Can anybody point me to the right place? I can't seem to find those instructions with the search engine.

THANKS!

As part of your "experiment" with eliminating suspect water, did you put any additives in the fuel tank and did you check the fuel filter for water?

AndyBees said:

As part of your "experiment" with eliminating suspect water, did you put any additives in the fuel tank and did you check the fuel filter for water?

Click to expand...

Yes and Yes. Every time it started missing I opened the Petcock and drained fuel from the fuel filter. At first it seemed like that helped. But now the problem is getting worse and worse and it doesn't seem like draining fuel from the fuel filter helps.

And both tanks of fuel have had additives put in them. The first tank had Heat and the last tank has had some specific type of diesel additive.

So, did you get any water out of the fuel filter?