Coilpack/Pos issue...help please

[andyg plym]

Ok before anyone says it YES I know a conversion is going to be better in the long run etc etc..... guys I know this but funds don't permit right now so will have to wait for a bit

Over the last few weeks noticed a misfire under load, idled fine so just thought it would be a coilpack issue rather than POS.

Went to ADI and was given some coilpacks to try and once installed it misfired even on idle so decided to put my old ones back in, put them in and now wouldnt idle on all 5 as it did before so I assumed it was down to the wiring that I would of disturbed.

Re-wired 3 of the coil packs as they were very brittle,put them back in and still rough, only idling on cylinders 1,2 and 3 (pulled the injector plugs off to narrow down),whilst it was running I pulled the plug off the N/S pos and it made no difference, so this confirmed it was definitely 4 and 5 not firing.

Received some POS units today to try and still the same.whilst the engine was running I also pulled the multiplug on the bracket where the other end of the POS unit connects and strangely this made the engine cut out.


I am guessing there is a wiring fault somewhere, the coils are effectively -/+ ?
I have narrowed it down to the 2 black wires that come off the back of 4 and 5 and go to the N/S Pos, these are the negative wires to coils.

[Error404]

Bit of wiring info Andy, hope it helps in some way.

Each coil needs:
+12v
ECU earth
ECU firing trigger signal
Engine earth

The two white connectors on the bulkhead are all +12v
Engine earth is via the eyelet normally fixed to the cam cover bolt.
ECU firing trigger and ECU earth are provided by the black and brown 4 pin connectors on the main harness side of the POS units.

For the two 4 Pin connector pin-out as follows: (This is off the top of my head so please double check the schematics!!!)

Pin 1 = Coil 3 trigger
Pin 2 = ECU earth
Pin 3 = Coil 2 trigger
Pin 4 = Coil 1 trigger

Pin 1 = Empty
Pin 2 = ECU earth
Pin 3 = Coil 5 trigger
Pin 4 = Coil 4 trigger

[andyg plym]

alex you are correct, just been reading up on quattroworld, its like i have no ground from the ecu end perhaps a pin issue but they all seem ok.

[Error404]

I am sure the ECU earth's for both POS units (all 5 coils) converge in the harness.
I am curious as to what the POS actually does? Is it an amplifier for the trigger signal from the ECU?

[S2central.net]

Have you tried swapping POS over to see if the non running cylinders move over too ?

[caterpillar]

be shure : the battery are ok.... and the generator volt are 14.4 or about... the the ignition will be ok.. and the cable connector too..

[andyg plym]

Got sent 3 pos units no difference, I swapped the multi plug ends over and it still only ran on 3

[S2central.net]

The POS is indeed just a signal amplifier - a Darlington arrangement iirc - it amplifies the trigger voltage that is flowing thru the primary stage of the coil. It allows primary coil current to flow for the dwell time programmed by the ECU. When primary current stops (Ecu trigger voltage drops sharply to 0V), a high voltage is induced in the 2ndary winding and it jumps across the spark plug.

[S2central.net]

If the fault stays with same cylinders then it's either a wiring fault or ecu gone bad.

Have you checked that 12V is present on all 5 pins across the white plugs ?

[S2central.net]

Wiring at the actual OE coil is as follows though -

- Engine earth 0V, provided by mechanical mounting to cover with earth strap - is also one end of the secondary winding
- 12V input (from the white plug) which goes into the one end of the primary winding (aka Terminal 15)
- Trigger input, provided by the POS unit - into the other end of the primary winding (aka Terminal 1)
- Secondary winding output - the HT end that connects to the plug

[S2central.net]

Fig 16.28 on this link explains the Darlington driver circuit pretty well

http://what-when-how.com/automobile/electronic-ignition-automobile/

For us the collector connects to the coil, the emitter connects to earth and the base connects to the Ecu.

It's better to think of the POS as a high current switching driver - it probably has an ability to clamp the max current as well for safety. But the main job provided by the POS is to avoid all those high primary currents being sourced directly by the ECU.

I expect there is something like 6-8 Amps flowing in each primary winding. The time taken for the coil to reach say 8A is the dwell time - controlled by ecu as a function of battery voltage.

[S2central.net]

If you search for Bosch ignition modules and things like BIM200 you will find links to Bosch datasheets. Max primary current for our OE items looks to be 8-10Amps.

[andyg plym]

ok update:

tested with ignition on and also engine running

white plugs both showing 12v
pos 1 and 2 reading 0.03v from ecu
pos 1 (cyl 1,2 and 3) connector to coils 12v
pos 2 (cyl 4 and 5) connector to coils 12v.

now pos 2 that i believe is the issue-the 2 black wires (these are cyl 4 and 5 negative right?), should I be getting 12v? Wouldnt of thought so.

[andyg plym]

is it possible to have fried these 2 coils? one is fairly recent but just thinking if the wires had been arcing across then they could be toast?

[UrS4boy]

AAN/ABY/ADU POS and Coil Info

Just got up (7:33 AM over here) and see that you might still need some help with this

If you follow the POS and coil testing info in this post (and its internal hyperlinks), I am sure that you will be able to narrow the issue down faster:

http://forums.quattroworld.com/s4s6/msgs/153152.phtml