Audi A4 TDi 9196 won't start (interesting problem?!) HELP!

31 Mar 2014
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United Kingdom
Hi all, another newbie here:- if this has already been threaded up then I apologise, but i have been searching for answers on the net for the past 8 hours with no joy so would be very grateful for some help:

My 1996 Audi A4 started losing power on a long run, and died after some 30 miles. I tried and tried to start it but to no avail. After over an hour, after some nagging from my wonderful girlf I gave it another go and.. hey presto it ran after I had bled the injectors and wiggled the wiring to the injector pump and took out the plunger in the stop solenoid (though it would not start when I had first done all this). Well, it ran for about 100 yards. Then stopped, never to go again...

The run up to this perhaps is that she has been smoking heavily when revved hard (car not girlfriend) when stationary. She splutters, gives off a lot of black smoke, a lot of carbon comes out of the exhaust and she often dies, but always starts again. But she always seemed to run ok (fairly normal smoke) at reasonable revs.

She's not using any oil, never has. She normally starts fine whether hot or cold. The glow plug sign comes on - indeed all the dash lights come on as normal and go off as they should. Sometimes there has been s a 3 beep series audible when I start her, but not always.

I have run her on a dual fuel system for about 6 months now - start up on Diesel then run on pure filtered waste veggy oil which is pre-heated by a good heat exchanger before going to the injector pump via a seperate veggy oil (heated) filter unit. The injector pump is a Bosch and they are usually very good with biofuels, however I have not been adding Turpentine as I normally would to break down any animal fat residues in the frying oil so I could to some extent expect the injector pump to go. But I would not necessarily expect loads of carbon coming out if that were on the cards, nor would I expect a broken pump to suddenly run again and then stop working again.

The central locking gave up bit by bit the past year, and it seemed to get worse when the weather was hot lest there be any electrical connection (haha).

I have tried connecting a good fairly high pressure lift pump into the fuel line just before the injector, but she still won't start, so it's not the vane pump in the injector as has been suggested on other sites.

There is a certain amount of black engine looking oil splattered around the turbo but I can't see where its coming from, it's been there some time and no more is coming out.

I have had the ECU out of the car today and can't see any 'dry' solder joints on it, though there was a load of oil in the little pipe that goes into a black plastic box on the ECU circuit board (not sure what that does or what that component is called... anyone?).

Normally I would suspect the injector pump as I say, but the fact that the car re-started that once leaves me baffled.

Something I don't understand is what the wires leading into the black plastic cover on the side of the injector pump do exactly - I tried to get the cover off but it only comes so far as it is obviously connected to something inside the injector pump and I didn't want to break anything by pulling too hard.

What I don't want to do is buy another ECU if it's the injector pump that's gone or vice versa: The starter turns her over good and fast, there are no strange sounds in the engine, the battery is fine.

There is no fuel appearing at all at the injectors when I crack them open during cranking. Could this be an immobiliser or other ECU issue? I'm not sure how they work...

Is there another ECM that could affect the injector pump (stop it from pumping) other than the main one under the corner of the windscreen?

Any thoughts or suggestions as to how to get the car running would be really appreciated, it has always been ultra reliable until now... desperate groans...banging head against wall...

I should add:
1) I now know that the little black box is the MAP sensor. Not sure how I'm going to clean it out - it's full of sticky black oil and the only hole is a 2mm internal diameter pipe going to it. But if this sensor is gunged up does that mean the injector pump would not inject at all?
2) I am feeding fresh Diesel in from a glass jar, through a brand new lift pump into the injector so the problem isn't filters.
3) People have suggested that it may be due to a pipe leaking somewhere fooling the ECU, but would any leaking pipes cause a total lack of injection, or would the car just run roughly because of it?

Thanks for any help, Jules
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Get the fault codes and hopefully they will point you in the right direction, otherwise you're just guessing.
Thanks Mursal. I haven't rushed to get the fault codes I must say, as people with problems related to various pressure sensor pipes, N47 valve etc have said that they are apt to give confused results often leading to more work. (Perhaps I'm getting to sceptical): What's the best way to get them.. does the car have some form of auto-diagnosis (if so how do I use it) or do I have to get some kind of reader?

BTW I can absolutely rule out a shortage of fuel supply - have checked the banjo bolts and the 'switch off' solenoid - one can blow cleanly through the injector pump from one to the other.

What I'm not sure about is how the immobiliser works - does it switch off the fuel completely using the 'off solenoid' or does it have any other effects? Anyone?

Thanks again Jules
I dont think the diagnostics will help much on this car being a bit older.
I would check the fuel shut off solenoid first, it should have a 12 volt feed either with key on or cranking.
You can remove it and check it across the battery if needed, the plunger should move inwards when voltage is applied to it.
I cant answer what the immobiliser cuts out as diagrams are not readily available.
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OK, try a bulb across the solenoid terminal and a good earth. The bulb should light when you turn the ignition on. Leave the solenoid connected to load the circuit, so the bulb will be connected alongside the solenoid (in parallel).

To read the codes you need at least VAG.COM on a laptop and a lead. But most small garages will have a reader and will read the codes for a set fee.
Black smoke is excess diesel. I'd be looking at faults with the injectr pump tbh, especially if you've been running homebrew biodiesel.
I'm not sure if your Audi has a fuel pump in the tank but that might be worth looking at too.
thanks for your help lads. I reckoned best not to waste anyone's time till I got the fault codes as recommended.. and here they are. Does this lot mean anything to anyone..? where do I go from here? thx again for any help :)

Address 01: Engine Labels 028-906-021-AHU.lbl
Part No: 028 906 021 BD
Component: 1.9l R4 EDC 00SG 0806
Coding: 00002
Shop # WSC 06435
VCID: 52AB9CCA9E4F4C8E727-4B36

8 faults found:
17978 – Engine Start Blocked by Immobilizer

00575 – Intake Manifold Pressure
17-10 Control Difference – Intermittent

00550 Start of Injection Regulation
17-10 Control Difference – Intermittent

01268 – Quantity Adjuster (N146)
18-10 – Upper Limit – Intermittent

00625 Vehicle Speed Signal
27-00 Implausible Signal

01268 Quantity Adjuster (N146)
17-10 Control Difference – Intermittent

00513 Engine Speed Sensor (G28)
27-10 Implausible Signal – Intermittent

00542 Needle Lift Sensor (G80)
30-10 Open or Short to plus – Intermittent
Readiness N/A


Address 15 Airbags Labels 8A0-959-655.lbl
Part No: 8A0 959 655 B
Component: Airbag V Audi D00
Coding: 00766
Shop # WSC 06435
VCID: 326BFC4AFE8F6C8E527-5198

1 Fault Found:
00532 – Supply Voltage B+
07-10 Signal too Low – Intermittent

just cleared all the fault codes and get:

01268 – Quantity Adjuster (N146)
18-10 – Upper Limit – Intermittent

no faults in the airbag

but still no joy... won't start. Not susprising, the injector pump is probably in need of a good bleeding as I've been playing about with the pipes to it... but what does this fault code mean in practice? new injector pump time? ECU fault? I'm stuck...

Hi all. Problem solved with a lot of help from some very kind people... thank you so much everyone who helped.

The solution is a nutshell: I bought an interface to read the Audi's electronic system and do fault resets using a laptop. One member in another Audi forum sold me a G28 engine speed sensor along with a used injector pump. I fitted the sensor first in case the problem was that, but got the same error codes repeatedly, one of which (engine speed sensor) refused to be deleted - it was there to stay. So I replaced the injector pump. Not an easy job as it's very fiddly to get some of the bolts in, working in a cramped engine bay, but it wasn't technically difficult. Then I checked the engine codes with my new software and was able to clear the problem immediately, and the car has worked fine since.

One oddity I found was this: I have two fuel tanks, one for WVO and one for the Diesel I start up and shut down on - they are controlled by a switch I fitted in the dashboard so I can easily switch tanks as I drive along. When I bleed my Transit there is a hand pump to push fuel into the injector pump, but on the A4 one has to 'use a vacuum pump' to suck fuel through. I used my mouth and it worked fine tp pul WVO through (I was waiting for the (late) delivery of a new Diesel filter). When I got the new filter, due to there not being apump on the filter housing, I tried to suck the fuel through by mouth again but it refused to let me, as though blocked, so I took the car for a spin and did what I have done on other cars - flicked the fuel tank selector from WVO to Diesel with the idea of drawing the air thorugh. What happened was that the car stopped and would not start and I had to get a tow home. There, I was able to couple in my laptop and found a mass of error codes. I cleared them all instantly then the car started and there has been no problem since. Perhaps air in the injector pump, or a vacuum confuses the sensors, I don't know, but perhaps this issue is worth knowing.

With loads of thanks again, Jules
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