Audi A4 1.9TDi died and won't start (interesting problem?!)

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The Progenator

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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...
 
Welcome to ASN

You might want to ask in the relevant A3 section.
 
Welcome to audi-sport.net. Enjoy the forum. :) x
 
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have you had the car scanned for fault codes?
also have you checked the fuel filter?

I would lift out the sender unit check the gauze in there make sure its not choked. check all the fuel lines.
change the fuel filter and fill it with diesel when you put the new one on and crank it over.

where abouts are you?
 
I would look into the fuel system either a pump issue, blocked filter or similar. The way tthe car failed sounds like fuel starvation to me.
The black pipe going to the ECU is the pressure tap from the engine. The MAP sensor is built into the early ECU's . It shouldn't have oil in it.

Karl
 
desertstorm said:
I would look into the fuel system either a pump issue, blocked filter or similar. The way tthe car failed sounds like fuel starvation to me.
The black pipe going to the ECU is the pressure tap from the engine. The MAP sensor is built into the early ECU's . It shouldn't have oil in it.

Karl
Click to expand...

Hi Karl and thanks for the help.

I have been trying to start the car on pure clean Diesel straight from a glass jar via a brand new lift pump, (but nothing is being sucked up), and of course I am cracking open the injectors, but there is no fuel throughput at all.

You may be right in that the car failed initially due to fuel starvation (- blocked filters happen very occasionally if my biofuel isn't clean enough, say, if my normal filtering process has failed for some reason) but then switching over to the main Diesel tank (electrical switch in the car) means that it normally runs on happily within a second or two of delay - in this case it wouldn't.

I do wonder if perhaps water had got into the biofuel and is sitting in the injector pump and causing a blockage? - but how can I check for this/remove it? Strange that it's not sucking at all though.

Regarding the MAP sensor, it appears that the little black MAP sensor itself is probably full of thick black oil, and I wonder, would that be enough to tell the engine to stop running/starting completely or just make it run roughly?

Is that little black MAP box something one can prize open to clean fully inside (it's like a little Breville glued together) or is it worth trying to flush somehow (won't be easy through that tiny capilliary opening about 2mm internal diameter)? If so, what might be safe to flush it with? I can't even get compressed air in there unless I drill an 'outlet' opening.

(If anyone has any photos of what they look like inside I'd have a good chance of drilling a hole in the right place, flushing it an re-sealing).

Before the engine stopped for good it felt rather like the way people describe 'safe mode' - do the older 1996 Audis A4's like mine have that?

Thanks again, Jules
 
any fault codes?

Defo clean that map pipe out and clean the sensor as much as you can, the sensor might be fubar if its full of oil, but the engine should run with it unplugged.

Use something like brake cleaner spray.
 
aragorn said:
any fault codes?

Defo clean that map pipe out and clean the sensor as much as you can, the sensor might be fubar if its full of oil, but the engine should run with it unplugged.

Use something like brake cleaner spray.
Click to expand...

Hi Aragorn, and thanks.

1. I'm not sure how to check for fault codes.. does that mean I have to buy a code reader or does the car have a facility to find fault codes built in?
2. The MAP sensor in my car is built into the ECU. Do you mean it ought to run if I unsolder it altogether? Or just take off the hose?
3. jbh thanks - when you say check the gauze in the sender unit - where is that and what does it look like?
4. jbh - I'm a Brit out in the forests of Sweden

thx again all!
 
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It may be an idea to have a vcds scan done on your car. This will let us know if your car has any faults that you can see. We have members on the forum that can do this for you. Where are you located?
 
Hi Sandra and Jbh, I'm a Brit out in ze forests of Sweden. Can I buy a scanner and do a vcds scan myself? What's a good one to go for and where from? Amazon and eBay usually deliver out here readily enough. It's an old car and I worry that I could end up spending too much on the auld Audi beast, but I really like her so don't want to lose her... :)
 
Ah didnt realise it was built into the ECU. Bit more difficult then!

VCDS should be your first step. You can buy cheap cables on ebay fro about £10 which gives you access to a trial version of the software which includes the basic functionality you need to read off codes.

I would be carefully checking the fuel system end to end for blocked filters. There may be a small gauze filter on the inlet of the pump itself so check there.

Running on Veg oil (especially used stuff!) isnt a good idea, and your now discovering why. On some old throwaway junker you dont care about then sure, glug it in and drive until it breaks. Otherwise either process it into proper Biodiesel, or stick to Dino.
 
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Can anyone tell me precisely the immobiliser works physically? I mean, what does it do once activated? Does it just affect the fuel cut off solenoid or does it have some complex function inside the injector pump? I'm wondering how I can bypass it just to check if it's that (though the lights on the dash are ok). thx J
 
The IMMO works on the ECU, rather than the pump.

As above, if it was an immo issue the engine would start then shut down after a short time, its not even as long as 30 seconds, more like 2-3secs. The immo light would also be flashing when that happened.
 
Thanks lads.

1. So if the immobiliser works indirectly - i.e. affects the ECU, then I take it the ECU not only manages the injector performance but can physically shut down the injection completely, rather than just 'messing it up a bit'? Is there a way of putting the car into a 'default injection mode', either by shorting wires or interfering with the injector pump itself? Since I removed the shut off plunger from the solenoid shut off valve, I would at least expect some default fuel suction and injection.. but there's nothing at all... does that mean it has to be the pump or could there be an ECU/electrical issue behind this? Can the ECU *TOTALLY* shut off the injector pump when it has no solenoid to help it do so?

2. Just to be clear, I have now had the feed pipes (banjo bolt etc) off the injector, and with the stop solenoid removed completely, one can blow right through the injector pump, so it's not a fuel supply issue.

thx again for all help, Jules
 
Thanks Aragon. Lots of good info in that link you sent me. Here for me is the crucial info:
"The spill valve is just a fast operating solenoid valve, it has 12v on its +ve side and the -ve side goes to the ECU, at the start of each injection sequence the ECU 'grounds' the -ve side and the pump squirts diesel for as long as the -ve is grounded. Contrary to common belief it's not a 'pass' valve like a tap turning off and on but rather a 'dump' or 'spill' valve (hence the name) . When not energised it dumps the fuel pressure on the high side of the pump through the valve, when energised it 'plugs the hole' and injection pressure is generated." It's a quote from: Injector Pump Spill Valve Solenoid Ticking Sound - Classic Estima Chat - Estima Owners

so now it's multimeter time :)

Regarding the MAP sensor on the ECU circuit board that's probably full of sticky black oil: I was presuming it would give a correct pressure reading whether there were oil in it or not, but then when I sucked the oil out of its feeder tube (by mouth - yuch!) I could suck but not blow - as though there were a non-return valve in it somewhere - which i hardly suppose to be the case - so I can't explain it. But I am wondering now if this is what is causing the ECU to work improperly? I will go and disconnect the thing and try to clean it out - God knows how - pray for me brothers :) Does anyone know what's in the black MAp box? Is it just a basic pressure sensor or is there more to it than that? Can I disconnect (unsolder) it or work around it even temporarily to see if I simply need a new one?

cheers Jules
 
you could try desoldering it if you think its doable.

I've no idea what the ECU would do though.

First thing you need to do is get the codes read out. VCDS can also show you live data, so it can show you if the MAP sensor reading makes some sort of sense. Afterall at startup and idle it should just be reading atmospheric pressure.
 
Hi all,
1. Well I have cleaned out the capillary hose in and leading to the MAP sensor in the ECU which was full of oil. No luck so far.
2. I can't find any instructions on the 'net (or diagram of the connections) to test the spill valve and its power supply from the ECU on the Audi A4 TDi 96 model... anyone know?
3. I do wonder if the fact that Diesel flows easily from the input feed on the injector pump to the 'stop solenoid' opening shows anything.. I mean, would the spill valve normally be open or shut when the car is stopped?
4. A fault codes tester is on order.
It's great, stinking of Diesel :) cheers all, keep the ideas coming!
 
The spill valve is on the high pressure side, so its after the stop solenoid etc.

The valve defaults to open, thus without any electronic control, no fuel delivery happens.
 
Hi all, I borrowed an older OBD2 tester.. not having any luck with it so far, no LED on it, but a new one's on order.
If the ECU is not getting power then would that mean no lights at all on the dash? (fuel, oil, immob etc). I wonder if it's not getting power, but i have checked the fuse. AS stated all my lights seem to be working normally - does that mean there is *definately* power getting to the ECU or are they seperate? Anyone?

thx Jules
 
most of the lights on the dash are driven directly by their respective circuits. If theres an "engine management" light then that will be fed by the ECU, but not many older A4's had that.

I'll sort you that PDF of the wiring out tonight.

You need VCDS, not some random OBD2 tester. The earlier cars dont talk standard OBD protocols.
 
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With the possibility that the ECU has packed up completely, how do check if it's actually working at all? And what basic checks are there (visual or multimeter) to see if there's an earth or power supply problem to it? I've read loads of posts now in many Forums and it's clear that there are a number of reasons for the car to lose power (as mine did over a period) and stop running but none I recall which show the car stopping permanently which relates to the MAF or Turbo control valve N75 or other feedback systems, so I'm wondering if it's a complete ECU breakdown?

The Magical Book of Hayne says that fuse 29 is engine management. Well it's not.. that's a blank fuse slot with no electrical connections at all. So having thought that a good electrical diagram analysis would help.. so far the problem's not got easier :)

Any good ideas anyone?
 
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Hi all, I have got hold of a computer analyser for the yet sleeping Audi... here are 2 photos of the readout, anyone know where I go from here or can tell me what the problem may be based on this new info? thx Jules DSCF2643DSCF2649
 
Go into the engine controller and clear the codes.

Turn it off and back on and see if any return, then try to start it and see if any return.

Could be a wiring fault or bad earth or something with that many fault codes, or maybe a blown fuse? But first step needs to be a code reset then see which returns!
 
Hi Aragorn and thanks once again.. I tried as you said and now get only one engine fault code (didn't test the airbag) and it says:

01268 – Quantity Adjuster (N146)
18-10 – Upper Limit – Intermittent
 
Hi all, I keep deleting the error codes and trying to restart the car/turning the ignition (electrics) on and off. First I got:

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

this came a number of times (and was back immediately I deleted it again and again. Until I tried to start the engine, then I got both these):

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

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

then finally I got just:
01268 - Quantity Adjuster (N146)
18-10 - Upper Limit - Intermittent

...repeating itself. That's as far as I've got.. any help with getting past either of these fault codes/cleaning off the sensor/checking wiring or any other good advice would be appreciated!

Desperate now... a month with no car... cheers Jules
 
i'd certainly consider changing the crank sensor in that case. I dont know enough about these engines to be sure, but i'd imagine that code cant really be anything other than a faulty crank sensor.
 
audi upgrades
Thanks for the help lads. @jbh how do I remove and clear that sensor from the pump to clean it? What both of you say certainly makes sense.
 
Anyone know if there's a limp mode on myA4 19.TDi (B5)? as I think mine's an early model. Its serial number is WAUZZZ 8DZTA 236955

It still won't start at all, I get the same error Quantity Adjuster Upper Limit (N146) error.

The valve JBH mentioned to check/clean at the front of the injector pump was fine - clean as a whistle inside and out.

I note there was some damage to the cable to the G28 - the outer cable had rubbed on a piece of pipe and was worn away but there doesn't appear to be any actual wire damage inside. Do you reckon the G28 not working could cause the N146 error or stop the car starting totally- I mean if my car doesn't have a limp mode? Someone said that was the case on another forum so I'm tempted to try another G28 before swapping the pump but without a ramp that won't be easy by the sound of it.

The G28 error is not coming up anymore, just the N146 error. But could one cause the other?
 
Perhaps. G28 is the main sensor which tells the ECU the engine is turning, and how fast its turning.

Many engines simply wont run without it. If theres some secondary sensor that allows the ECU to figure out the crank speed then it might start in limp mode, but not always.

Most ECU's have limp mode, and your TDI almost certainly does, but theres some stuff you cant limp around. If the ECU cant tell the engines actually turning, theres not much it can do!

Have you done any searching on the QA error? I found this for instance:
Quantity Adjuster Problems - TDIClub Forums

Which has a few tips (case PRV, seals and stop solenoid plunger?)
 
Get the injector pump off, you broke the quantity adjuster hence the no start condition. I have fixed pumps before by making a good one out of two bad ones...
You will find a piece of metal broke from it's cam/lever, it will need replacing and hope the pump body is not scratched by the debris !
 
SOLVED

Hi all. Problem solved with a lot of help from some very kind people... thank you so much Aragorn, JBH and 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 here 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

Engine Speed Sensor
 
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