Thread: 3.5 EFI V8 - only 1 single spark

Thanks Brad and Randlover,

I'll try those tests as well, cranking by hand should also tell a bit too with some luck. I'll have to wait until the weekend, its pretty cold here right now.

Thanks also for the link, the SD1 V8 looks like it is probably the same and that parts and diagnostics process will help also.

Originally Posted by Slunnie

Thanks Brad and Randlover,

I'll try those tests as well, cranking by hand should also tell a bit too with some luck. I'll have to wait until the weekend, its pretty cold here right now.

Thanks also for the link, the SD1 V8 looks like it is probably the same and that parts and diagnostics process will help also.

Its the same, the location of the coil and some of the accessory fit up changes but electrically they are the same

Originally Posted by Slunnie

Thanks also for the link, the SD1 V8 looks like it is probably the same and that parts and diagnostics process will help also.

If you have what is detailed on that page then you have a reluctor distributor / electronic ignition module and most stuff I said is not applicable. The only test you can use from what I detailed is the battery on the coil for a spark. There are no points and unless you have an oscilloscope and know how to use it diagnosing a lack of spark is going to be a challenge.

With a reluctor there is a minimum speed the rotor has to move to achieve a spark and you won't get that barring the motor over.
If you check the coil and it's ok, then the problem is either the distributor or the ignition amplifier.

Let's see how far you get on the weekend and we can work from there.

Originally Posted by RANDLOVER

You could try heating or cooling the electronic module to improve a bad solder connection as a test. Options are hot or cold (fridge) water, heat gun, put part in freezer then quickly install it.

Originally Posted by Blknight.aus

if its the EFI with the electronics module on the side of the coil its the electronics module failed.

Ok, I've just realised the electronic module is the same as the ignition amplifier module and not a black box somewhere. Thats the one located on the side of the distributor - there wasn't anything on the side of the coil

Originally Posted by BradC

The 2 wires to the positive side of the coil are to supply power. As already stated, normal running through the ballast resistor, but when cranking full battery voltage across the coil for a much fatter spark. The negative side of the coil is always points switched.

To test the coil, put a spark plug on the HT end earthed to chassis and just put 12v on the coil with a set of wires. When you disconnect the 12V you should get a nice fat spark.

Thanks, I did this tonight and got a spark. The coil seems to be working ok. I also did an intermittent short on the + side and was able to get multiple sparks from the spark plug also. Voltage direct from the battery to the coil also gave the same result as previously with the spark on disconnect and no spark when cranking.

Originally Posted by RANDLOVER

Here is a thorough testing procedure for a Rover SD1 V8 3.5 litre which I believe is similar...
Rover SD1 - V8 Electronic Ignition - Components and Testing

This has been really helpful! Thanks!

Originally Posted by BradC

If you have what is detailed on that page then you have a reluctor distributor / electronic ignition module and most stuff I said is not applicable. The only test you can use from what I detailed is the battery on the coil for a spark. There are no points and unless you have an oscilloscope and know how to use it diagnosing a lack of spark is going to be a challenge.

With a reluctor there is a minimum speed the rotor has to move to achieve a spark and you won't get that barring the motor over.
If you check the coil and it's ok, then the problem is either the distributor or the ignition amplifier.

Let's see how far you get on the weekend and we can work from there.

Yes, the electronic ignition. I went to dive deeper into the distributor, but was very quickly met with a plastic cap that said not to open it, there is nothing servicable and it is all factory preset. I checked the wire to the distributor, when removed there was no spark (probably should have expected that!) However now diving into the ignition amplifier which I didn't realise is the same as the electronic module I think I may have found a problem... under the ignition amplifier module plug boot the wires look like they've split - seeing this, it wouldn't surprise me if this is a problem - I'll try to get a better look at this one but if the wire(s) are broken then that would be a show stopper and make a whole lot of sense. I was surprised that it has a 3 pin ignition amplifyer, but only wires to the 2 outer pins.

For the wire to the starter, I couldn't get into there, it was so tight, everything completely conduited in split tube and zip tied and then covered in oil. Hopefully the test with the battery direct to the coil isolated out the problem of the wire dropping off the started - I may need to revisit this though.

Originally Posted by Slunnie

Ok, I've just realised the electronic module is the same as the ignition amplifier module and not a black box somewhere. Thats the one located on the side of the distributor - there wasn't anything on the side of the coil


Yes, the electronic ignition. I went to dive deeper into the distributor, but was very quickly met with a plastic cap that said not to open it, there is nothing servicable and it is all factory preset. I checked the wire to the distributor, when removed there was no spark (probably should have expected that!) However now diving into the ignition amplifier which I didn't realise is the same as the electronic module I think I may have found a problem... under the ignition amplifier module plug boot the wires look like they've split - seeing this, it wouldn't surprise me if this is a problem - I'll try to get a better look at this one but if the wire(s) are broken then that would be a show stopper and make a whole lot of sense. I was surprised that it has a 3 pin ignition amplifyer, but only wires to the 2 outer pins.

The insualtion itself failing isnt usually the issue its the electronics in side. If you're only getting a single spark on power up or power off one of the power transistors inside or an internal cap has failed. Technically its not a field servicable unit and if you're handy with a wiring diagram and wiring you can adapt the dizzy to use a different ignition amp. When you put it back together if you have the replacement which has the metal backing to go onto the dizzy housing make sure you give it a good coat of thermal paste, or dialectric grease so it can heatsink onto the dizzy housing, without it they last about 15-20 minutes. The ones with the complete rubber casing dont need it. (the 2 units are functionally the same but have different internals)

Excellent, thanks for this Dave. I'll check the continuity tomorrow as there didn't seem to be much left with the split, and then if its flowing then I'll put a new ignition amplifier into it. thanks for the heads up on the heat sinking issue too!

Just an off the wall thought.
Do you know that if someone has pulled strongly on the rotor at some stage it is common for the rotor shaft to become detached from the dizzy drive? The only safe way to remove the rotor is to break it with a set of multigrips or similar.
Regards PhilipA

Originally Posted by PhilipA

Just an off the wall thought.
Do you know that if someone has pulled strongly on the rotor at some stage it is common for the rotor shaft to become detached from the dizzy drive? The only safe way to remove the rotor is to break it with a set of multigrips or similar.
Regards PhilipA

Thanks Philip, I'll check that too. The plug is currently in the lead direct from the coil, but in terms of it triggering the timing, I'll check that too! Nothing would surprise me with this thing!