No Sparks

[Guest sps137]

hi all, i'm trying to connect just the ignition/injection sub loom but cant get a spark. The previous owner had cut the feed from the eecIV box in half but i'm pretty sure that i've reconnected them correctly (several hours with a multi and haynes manual). I've connected the 2 large and eyeleted wires to the battery and also run a wire from black on the spare (5 wire) connector block to the battery live. The fuel pump clicks in for a second then shuts down as it should but it will not start up again when the motor spins and i'm getting no spark output from the coil. ( i have 12v across the coil). Reading previous posts it appears that i should be using a brown relay in the original loom, What does that feed to on the sub loom, i had assumed that the main power came piggybacked from the starter motor feed. There is also mention of two earthing connectors, but i can only find one (not including the permanent retarding wire). Is it possible that the dizzy sensor is at fault and so the ecu doesn't think that the engine is turning. Just as an aside can someone explain how the ecu advances the spark as engine speed increases. As the dizzy seems to have no mechanical advance surely it can only fire when it lines up with the ht output posts, irrespective of rotational speed.

 

simon

[Guest Ant]

I had a non-firing engine when I first put it in the 2B, and this was due to a dizzy fault. If the fuel pump doesn't re-start when you crank the engine then it's almost certainly the dizzy sensor, or the wiring to it, which is at fault.

 

The Dizzy sensor has 3 wires. One 12v feed. One ground. One output pin (middle one I think, but don't quote me). this output pin goes to both the ECU and the ignition module.

 

A couple of tests:

 

- Disconnect the dizzy plug. Stick a wire into the connector on the loom at this "output" pin. Put the ignition on. Fuel pump should start and stop as usual. Now get this wire and tap it a few times against the chassis. This should re-start the fuel pump and you should hear the fuel injectors click too. If that all happens then it's the dizzy sensor which is at fault. Get a replacement from a scrappy - they're about a fiver.

 

- Second test. With the dizzy removed from the engine but connected to the loom, put the ignition on as before, wait for the fuel pump to stop, and then spin the dizzy. Again the fuel pump should restart and the injectors should click. Looking into the top of the dizzy there is a aluminium disk which turns with the shaft. There's a gap in its edge which passes the sensor. As it passes the sensor should connect the output pin to ground.

 

- Third test. Remove the dizzy completely and disconnect the loom too this time. Then put 12v and 0v onto the + and - connections on the sensor, and put a volt meter between the - and the output pin. The volt meter should read 12v most of the time, but as you turn the shaft the volt meter should drop to 0v once for each revolution. If that doesn't happen then the dizzy sensor is knackered.

 

From the first two tests described above, if the fuel pump restarts and the fuel injectors click then you should also get a spark at the spark plugs. The 12v at the coil will flip to 0v too but that will be too fast to observe unless you've got an oscilloscope I reckon.

 

Good luck!

Ant

[Guest sps137]

thanks a lot ant, i'll try those tests out tomorrow

 

simon