1991 Coupe 2.3e Ignition Problem HELP

[R5T]

Evening lads & ladettes

Iv'e posted the same topic on the classic Audi forum, but have only had one person help me out properly. Despite his guidance and help I am still completely stuck, and would really appreciate any help seeing as all you bods are 5 pot gurus'.

Here is my problem:

Around 2 weeks ago I was looking into my cold start/idle problem, the car was running rather lumpy and labouring on cold start. Once the engine had got up to temperature she ran alot smoother.

I had the ISV off and cleaned all I could, and cleaned the electrical connector etc. As you guys know, when the ignition is turned on you can hear the fuel pump priming. I changed the fuel filter hoping that with a clean filter and 20ltrs of fresh fuel would potentially help out the idle problem.

The engine was running lumpy and struggling to pick up revs on the throttle. My old man was fiddling underneathe the bonnet and pressed the WOT switch, which cleared the tickover and increased the idle revs. From then on the engine would run smooth at was not so intermittant rev's wise.

Fast forward a couple of days and I had gone out to the car and started her up, on the first turn of the key she wouldnt start, but on the second she started on the button but was again running lumpy. We pressed the WOT switch and it made no difference. I unplugged the ISV and the revs dropped even more, plugged it back in and the revs stayed the same.

After a minute or so, we managed to get the revs to pick up and she was running a bit smoother. My old man held the revs on the pedal at approx 2-2500 rpm for no more than 15-20 seconds, he came off the pedal... the revs dropped and the engine completely cut out dead. No spluttering or labouring, just as if someone had turned the key off.

Since that day approx 2 weeks ago I have not been able to start the car.

When i turn the ignition on, the fuel pump makes NO noise whatsoever, so i thought id check the relay (215, position 10), all was intact and the fuse was all good.

After a bit more faffing about i decided to see if i actually had any spark ... to my amazement there was no spark from any of the 5 leads. I put a buzzer on both coil pins and got no "buzz".

The camshaft is turning and the engine is turning over fine, but with no fuel and spark, obviously she will not start .. just keeps turning over and over untill the starter motor spins off.

To see wether the relay for the fuel pump was working properly, I took the casing off ... and with the ignition "on" pushed both of the contact points together ... "hummmmmmm" the fuel pump springs to life. Tried starting the car knowing that there was now petrol up top but still with no spark obviously she was having none of it.

I checked numerous fuses etc. and I couldnt find anything untowards.

The fellow on the other forum suggested that maybe the ECU in the passenger side kick panel could be up the shoot.

Now iv'e seen this "unit" listed as an ECU and ICU and an ANTI KNOCK SENSOR ECU, all with matching part numbers to the one on mine.

I was of the understanding that this ECU/ICU was responsible for the power delivery to the ignition circuit and the relay to the fuel pump.

So I ordered one, mine had sat in an extremely damp car for god knows how long, so I was adimant that my unit was ******ed, and this was my problem.

It arrived this morning, and once I had returned from work, I went out the car, dis-connected the battery, and swapped my ICU/ECU for the new one. (I am 99% sure that the new one is good, as it was tested before it was sent.) And re-
connected the battery.

Put the key in the ignition, turned it and to my utter frustration ... No difference whatsoever ... No power to the fuel pump and still no spark.

Sorry if any parts of my description are vague or not described very well. I have told you everything I know/have been told.

I am under the impression that the 2.3 NG has two "ECU" units and the the one in the passenger kick panel is the "IGNITION CONTROL UNIT" .. Is this correct ? and if so where is the other one ?

Now I am not a mechanic so without baffling me could anyone give me a clear cut and understandable break down of how the ignition system works and what procceses it has to go through ? As in " the power comes from the battery, goes to the bla bla, this sends a signal to the such and such, which in turn powers the coil, which sends a message to the gigledeeflip, which sends power to the relay, which tells the ECU to go, which starts the car ..." (i think you get my drift )

Atleast then I could have an informed "proccess of elimination" to carry out, If anyone can help, then if at any point you mention a part/sensor etc. then give me a brief description of where it is as I am not totally familiar with these cars.


Sorry to go on and on people, but I am really stumped as to what to do next ... the car is a 91' H-Reg Audi Coupe B3 2.3e 10v NG fwd.


If anyone has any idea or any suggestions then please drop a post, Im really struggling here and wanna get my baby on the road

Any help is greatly recieved ...

Thanks

Sam

[djh]

sounds like a distributor/hall sender problem. Also are you getting a spark from the coil to the dizzy?

[R5T]

Thanks for the reply mate,
Please excuse my ignorance but ... how would I check to see wether I had spark from the coil to the dizzy ? I put a buzzer across the top pins on the coil and got no buzz from the coil itself .. Can you test the coild like that to see wether its getting power ?

Also, does the 10v NG have a hall sender then ? THat was 1 thing no one could answer ? if it does where can i find it ?

Thanks again

Sam

[sam80quattro]

i had a similar issue with a 1.8 80 a good few years ago now and it was the wiring to the ecu that came through the bulkhead had chaffed through and finally ended up in it not starting after eating rotor arms on a weekly basis. new bit of wire and some better insulation and all was well

[R5T]

Cheers for the reply bud, was it too much of a pig to replace the wiring ? or do you need to know what your doing properly ?

Thanks

Sam

[sam80quattro]

Just cut the bad bit out and soldered a new piece in its place...

[Sleeper_Avant]

start with the basics, rotor arm condition always the first place to look if the coil doesnt discharge it will not recharge for the next spark, if that makes sense

have a look for any cracks or white marks on it



3 pin connector on the distributor means a hall sensor is inside (it will have lol)
this is basicaly an optical window, but pull the dizzy cap off and you will see inside under the rotor arm (that is probebly nackered )

Sean

[HORCH]

yeah get a new distributor cap and rotor arm,

to see if your getting a spark from the coil to the dizzy take the centre lead off the dizzy cap and hold it with some pliers close the the body or the cylinder head or something and get someone to turn it over

[mcandmar]

I had similar fun with an NG before, very difficult to start, and flat out refused to restart when warm. Long story short, the issue was a faulty coolant temperature sensor. Its a small two pin sensor on the head, 1 pin gives a signal to the fueling ECU, the other gives a signal to the Ignition ECU. The condition i got was also no spark, power going to the coil but no trigger to it, disconnect the temp sensor and it burst into life. So basically a bad signal, or dead short will prevent the ignition ECU from working. Try disconnecting the temp sensor and see if you get a spark.

The small unit in the kick panel is the ECU for the ignition system, there is also a conventional looking ECU in the normal place that runs the fuel injection. It is a mechanical fuel injection system but the NG has the ECU to fine tune the fuel mixture using a small servo unit in the metering head. Its basically an emissions control device.

Ignition timing was the second part of the equation, was way out on this car as the head gasket and timing belt had been replaced. From memory the timing is something like 15 degrees BTDC, and you have to set it using a timing light on the flywheel marks.

If you need to set the ignition timing up from scratch find TDC on the flywheel (confirm cyl 1 is TDC so your not 180 degrees out), then confirm the cam wheel lines up with its timing mark on the valve cover. Once you know for sure the timing belt and cam is right have a look inside the dizzy. There is a mark on the inner rotor and outer body of the dizzy that you line up with each other when the engine is at TDC. Next turn the engine over by hand until you find the timing mark, 15 degrees* or so before the TDC mark. Once you find it clean it or paint it so its easy to see and then start the engine. It will run like crap as the ignition timing is out but keep it running long enough to fully warm up, then stick a fuse into the fuel pump relay. This disables closed loop mode, sets static ignition timing, and a few other things to allow you to set the ignition timing. Then finally using a timing light turn the dizzy until you get the timing mark you painted in the middle of the window in the bell housing. Tighten dizzy, remove fuse, and test drive.

[HORCH]

also, it could be the warm up valve or the fuel mixture at the fuel distributor causing the running problem,

have you listened for the fuel pump whirring while turning the car over?

[R5T]

Hi all,

Thanks for all your posts, I am getting no whirring from the fuel pump as I mentioned in my first post, and no spark, I can only assume that this is electrical, the dizzy wouldnt be getting any spark if the coil is not feeding it and the fuel pump relay is not getting power either. My question is what feeds both of these units ?(pump relay & coil). Today found out the my heater matrix was f***ed and was piddling water everywhere, i located the main ECU up behind the matrix etc. and assume that this may have been getting wet. Could this be the problem ?

Thanks

Sam