V6 quattro sedan is calling to me...

[S2central.net]

I'd go back to first principles... Look for crank and camshaft pulses first... Check all fuses... Check that fuel pump is running... injectors are pulsing ... and that its trying to spark...

Any fault codes telling you anything yet ? I could maybe get a race over in the next week or two if you are stuck. Its gonna be something stupid.

Any chance you have inadvertantly open a hidden kill/immo switch ?

[gunman]

got no spark of any sort on any lead, main suspect is the cam sensor but my shareware vagcom nor my fault code reader will communicate with the car. It's a bit dear for a hit and hope approach. A mate is bringing a snap on diagnostic unit down tomorrow and we'll see what it says.

[S2central.net]

Heres the engine schematics for a 92-93 AAH beastie...

http://www.s2central.net/S2_Schematics/B/B50.PDF

Tis Hitachi MPI pish though - not zee Bosch Motronic

[gunman]

Paul, I can hear the fuel pump priminng on ignition, no spark at all. Any idea how to test the cam and crank sensors with no more than a multi meter ?

The cam sensor had the black plastic plug broken off the top of the sensor, still had wires connected tho, thats why it's top of my suspect list at the min.

The car at some stage had an aftermarket alarm which i was told had been disabled and right enough drove Ok. My first thought was the imobiliser had kicked in again and i found a small toggle switch in behind the bonet release. didnt matter which way i set it, still dead so I took it out and bypassed it, still nowt. I have heard that the diagnostics socket connects to the ecu via the imobiliser (factory) biut my car has s flat plastic handled key so dont reckon it has one (would of explained why diagnostics didnt work)

[gunman]

Thanks for that, not sure how much it'll help as I dont understand it

I'll study it more tomorrow and see if it makes sense.

by the looks of it theres 2 crank sensors?

[S2central.net]

Hah - thats a bug and a half... only shows one POS unit and three of the six coils on the AAH schematic...

Would be too weird for both POS units to die at same time - check fuse 32 which provides +ve feed to all the coils.

Check fuse 21 is OK - that provides +ve feed to the black OBD plug which is needed to get VAGCOM to work.

[S2central.net]

If fuses are OK... then I'd also suggest camshaft sensor - thats G40... WIth an LED tester you should see a pulse from the signal pin every camshaft revolution.

You really need a scope to test integrity of the crankshaft sensors - one of those (G4) is a reference pulse every rotation. Whereas G28 should be like a sawtooth signal generated by flywheel teeth - its used to calculate RPM. Search the forum for waveforms on the S2 - they will be similar looking signals to those.

[gunman]

cheers Paul, will check all tomorrow.

Good to get advice from someone who knows what they're talking about

[S2central.net]

Eyy up - just looked at the schematics again... properly this time... That V6 must be wasted spark - note how the coil packs have two outputs.

Would still be weird for single POS unit failure to kill all channels - unless its bad earth or something. Check that fuse (and all the ECU fuses actually) and the primary sensors mentioned.

[gunman]

checked every fuse, no blown ones, My attention was drawn to the alarm so i actually spent most of the evening discionnecting it, still no difference. The cam sensor has brown/black as earth, yellow/white was around 6v, red/black was close to 12 and dropped to a steady 5 under cranking.

Still no further on but the snap on diagnostics didnt even connect and I found out something that seems strange. I thought the white plug went to the ecu but on this it goes to the 2 posts beside it, both of which are live??????? I'm leaning towards an ecu fault now, how do you get the ecu out?

cheers.

[Flat on my back]

.

I would have expected a +5vdc regulated supply to the cam sensor, with the return pulse going from near +5 (+4.8 measured on mine) down to 0v in a square egde pulse.

Eg. top trace.

[gunman]

hmmm, your meter looks a bit more advanced than mine

[S2central.net]

Mmmm - something doesn't smell right... As Carlos says - I'd expect nominal 5V coming from ECU to that black/red wire on the camshaft sensor (G40)...

I've never had hands on that engine before - but the signal on Carlos scope is what I would expect - there is something wrong in the wiring - check that the alarm install hasn't ******ed anything up or that wires are rubbed thru somewhere.

I have an ECU breakout box that can be used to buzz out every pin on the thing - if it comes to that.

I can't remember what the K&L pins (white OBD plug) do when not in use but +12V doesnt sound right.

Looking at schematic again - I see that G40 and the OBD plugs share the same connector block - labelled C on the drawings - there *might* be some loom damage that is common here... Strange it to pop up after a week of good behaviour - wonder if this was niggling reason for sale of car in the 1st place (yikes)... Or have you been working in some area that could have caused it accidentally ?

Remove Fuse 28 and see if you still get +12V at G40 (and the K/L pins).

[gunman]

TBH some of the wiring under the dash can only be described as an abortion! It took a right bit of figuring out what the alarm had been wired to and beleive me it wasnt a professional job! Only work I did before this happened was to take off the air pipes to check for leaks.

[S2central.net]

I feckin hate aftermarket wiring monkeys... It should be a criminal offense to do such shoddy work... I'd probably need 1/2 to a full day to unravel the mess and sanity check the ECU wiring to all its sensors and such... Could get real lucky and find something obviously nasty in a lot less time, but I couldn't promise that. Other thing I can't promise is when I'd get over to look at it. If you want that sort of help - let me know and I'll see what I can do... Maybe an evening would sort it if the car is in a well lit garage ?