Another ABF non starter: Help please deciphering Vagcom data...

Have an ABF that cranks but doesn't fire, no visible spark at king lead (hard to tell as daylight) , smell of fuel;

ECU: Engine : 037 906 024BE Digifant 3.2 2121
Immob: 6H0 953 257B

New plugs, coil, leads, rotor arm measures 2K, cap looks good.
New crank sensor, now read 459rpm on live data when cranking.
Relay 30 changed, no blown fuses.
Dizzy turns, no.1 cap pole corresponds with correct position of the engine valves.
Have compression, fuel in tank. Easystart doesn't help.
All sensors plugged in.

Vagcom showing no faults in Engine ECU or Immob ECU

Vagcom live data (not cranking) ;
Group 1: 378rpm 16C temp 0.66Volts 0000 0000 binbits
Group 2: 378rpm 45.39mS inj 13.97Volts 22C temp
Group 3: 378rpm 0.0% load 0.0% TB angle 22C temp
Group 4: 378rpm 0.0% load 0255.0 no units 0010 0000 binbits
Group 5: 378rpm 0.0% load 0.0 no units 0000 0000 binbits
Group 6: 0.0 0.0 41.0 57.0
Group 7: 41.0 127.0 10.0 77.0
Group 8: 0.0 0.0 250.0 239.0

Is there a website that decodes this data? There may be a clue in there
eg: the TB angle value doesn't change when I press on the accelerator???

Anybody else have any suggestions of what to try next?
So far, I have 'burnt' 4hrs on this........
Thanks
Jon

 

You can update the data in vagcom. There was some info on here by G60Dub

Edit. See here.

http://www.clubgti.com/showthread.php?t=199583

Regarding the throttle. Have you checked wires behing inlet and above exhaust manifold. They get burnt and crispy.

 

Some progress. I have put another s/h coil on it, and it sparks once?????????????????
Then it just cranks, and cranks.

Anybody?

Going to buy another new coil, tomorrow.
Regards
Jon
Epic info in the thread attachment, cheers

 

Hmm...I have seen this before...

I will have a good think...

 

You might wanna check coil resistances. Mk3 coils are crap at the best of times.

 

Thanks guys, itching to get out in my new 'smoker'
Jon

 

More research says the coil is actually a coil and amplifier combined. As such, with active electronics inside the usual ohm's test is not sensible.
So new coil it is then.
Fitted.
No difference.

Think this post will be useful when I do bottom the problem, as others seem to have a similar story to tell.
Next: looksee at the ECU schematic, to try and use a bit more science, rather than trial and error.

More thoughts invited...
Jon

 

The coil sparks with initial key on/engine off but not with engine running?

On VCDS (Vagcom) you are registering engine cracking speed of < 450rpm too?

 

I get one spark as soon as I turn the key against the spring loaded bit to engage the starter.
I have tried running a wire from the starter solenoid and touching to bat +ve with the ignition on to try and eliminate the possible ignition switch fault. No change
I can see about 459rpm on the vagcom data after a 5 or so sec crank.
It reads 376 (?) at zero!
Any more thoughts?
Ta
Jon

 

The lack of ignition output points to the ECU not having a clean engine speed input.
Have looked at the big 28 pin connector on the side of the engine, to ensure connectivity?
Also on cranking is the fuel pump turning on? if it is not then your engine speed is not present despite the lack of codes.

Also did this car come like this. Was there work done to the vehicle that maybe related to this problem?

 

The speed sensor has its own 3 pin plug, so doesn't go through the 28 way unit.
Its a new sensor and felt good when I plug it in.
I have rigged an oscilloscope up and there is no train of pulses in the middle of three pins of the coil connector.
I have point to pointed the green/red wire from the coil plug back to pin 8 of the ecu, so there is continuity.
Need to find a pin by pin drawing for the ECU next.
The fuel pump primes for a few seconds when I turn the ignition on
Bought the car as a non runner. Previous owner had tried and failed. (love a challenge, usually..)
thanks
on

 

power supplies (ign on and off and cranking) correct and as expected to ;

pins 23, 9, 7, 38

Jon

 

Rubjohnny has the ECU wiring diagram in his signature.

Our symptoms included a weak/faint single spark only... Work on a common ground on the block. Check ground to gearbox.. crank sensor changed... if anyone offers a working ECU+IMMOB+KEY swap test, take the offer!

 

I'm thinking grounds also. There is a nice fat one fitted between the head to the coil.
Funilly, the single spark I get only happens with an original Beru coil. The other two new 'no name' ones don't do a thing. Zilch.
Going to do all the checks possible with the ECU disconnected tomorrow. Measuring resistances of throt pot, water temp etc

After that, I keep coming back to an immobiliser or ECU fault. If all the checkable inputs to the ECU are correct, it must be the uncheckable, r the ECU itself?
Jon

 

Normally on these if immobilser fault, you get it start, run for 2-3 secs max then shut off and you will get a code 'engine start blocked by immobiliser'

http://wiki.ross-tech.com/wiki/index.php/17978/P1570/005488

Have you got good battery voltage to fuse 15? This will prove if ignition switch duff.

 

That single faint spark... And we switched coils... same thing... we didnt have a VAG port and I wish I had, your crank sensor seems unhappy??? So I'd be looking closer into it first.

Don't be spending too much time on the hall sender in the dizzy either, that wont prevent ignition.

 

All great help, and its needed. Most of yesterday was 'used' on this.
Will check fuse 15, but I have already checked all the power 12V input signals to the ECU. They are all present and as expected. (pins 23, 9, 7, 38)
It is nice to know the engine will run without the dizzy plugged in, as I was beginning to think that was where to look next. (ie it is a proper wasted spark system, not a fully sequential system needing both crank position signal and cam position (from the dizzy) .
Next, I think I will rig uo an abf crank in the lathe and lash the old crank sensor V signal on my scope once power and earth are connected.
That should give me confidence to do a similar chack on the car signal.
I still don't understand the 378rpm level with the engine stopped. Why? Its not magnetic, so should read much lower!
Also, 459rpm cranking. Does the starter go that fast? I would have expected 2-300rpm

Unplugging the coolant temp sensor to the ECU doesn't bring up a fault code. Either static or cranking. Why? Is vagcom telling me the truth?
The 5V supply voltage to the throttle pot measures 6V (on my 10 quid meter). Is this normal?

Was beginning to work myself back to the immobiliser, but after reading Ross Tech (good site) I will try and ignore this, for the time being

Looking forward to a bit more progress on this today.
Jon
Good news is I found a superchip 256K memory chip inside the ECU, so that was a bonus. Just in case I swapped it out with a standard one, no change
to target the pulsar wheel. As the lathe is proper variable speed I can (hopefully) see the square wave 0-12park is initiat

 

Spinning a 18T crank in the lathe and checking the old crank sensor produces the expected hz signal on my multimeter against lathe speed.
So the orig sensor is ok
Putting another ECU in and cranking does not cause the engine to burst into life for 3 secs then die due to immobiliser.
Other ECU is recognising the wrong car immobiliser though
Work continues.........
Jon

 

Crank Sensor connection

We had problems with the crank sensor connection. A long time after getting the ignition sorted, we had bad stuttering and misfire. We noticed the crank sensor connector housing was split and I think the mounting bracket would slip into the connector and short. This had no effect during no spark state, we would have checked many times, just saying that our's is broken and split and needs care.

 

This bit from Ross Tech above has got me thinking;

" If no other immobilizer related fault codes are stored and the immobilizer related meas. blocks are fine except Engine Start not allowed, in rare occasions it helps to try cold-booting the car. Remove both battery cables from the battery. Short the battery cables together (away from the battery) for about 15 seconds. Reconnect the battery. (Example)
Low battery voltage (including a faulty battery) may cause Immobilizer system malfunctions and testing should be done only with a known good battery installed. "

"Engine start not allowed"

Would be nice to know what this means..............
Jon