36 replies to this topic

[nicomasala]

Hi All. 

 

First off, sorry if this has been covered, i have read so many topics on electronic ignition that my eyes have gone blurry. 

 

I have a MG Metro engine, that came with a 65DM4 distributor. 

 

I have taken a feed from my fuse box, and have 12v+ at the coil (changed coil to correct elec Ign one as per other threads). I have run the 12v feed to the distributor from the + side of the Coil and returned the other wire to the negative side of the coil. 

 

I have no Spark

 

I have taken the dizzy cap off and the rotor arm moves with the engine. 

 

At this stage im thinking it must be the dizzy that is bad, as it wasnt new and was sperate to the engine when it came. 

 

One other thing that im unsure of is the Coil bracket, it is a plated (Shiny) one, and im wondering if this is interfering with the coil grounding? does the coil need to ground from the negative pin to earth, or at least via the coil casing to earth?

 

Can anyone suggest a test for the dizzy, i have read some online, but they didnt really make sense to me. 

 

Thank you for reading, and if you have any suggestions i would be greatful. 

[gaspen]

Did that engine run before with that dizzy ?

 

Are the ignition leads pluggedd in the correct firing order?

 

 

 distshaft.jpg   46K   10 downloads

[cal844]

Is there an engine to body earth fitted?

Id be trying a short length of wire from the coil negative to the earth point on the body, then check you have a spark.

If not Try another coil I'd also check for voltage at the module (remove the wiring connector and check there, should be live along with the 12v coil feed). If you have power here then I'd say the module is scrap and needs replacing

[nicomasala]

Thank you for the replies. 

 

The engine was sat inside the shell when i bought the mini, the distributor was in a box with a new cap and rotor. 

 

I have checked the angle and plug lead location and all seems ok. 

 

I ran a lead from negative coil side to body, and nothing changed. 

 

12v at the module feed on the red lead. 

 

I have two engine to body earth leads fitted. 

 

My current thought is to just replace the distributor, module and all etc to rule that out, ive been working on her for two years to get to the running stage and just want to hear some noise now :)

 

Thanks guys. 

 

Nick

[cal844]

I'd say that the module is fried, order 2 so that if it happens again you have a replacement.

[nicomasala]

Replacement module, cap and arm ordered just to be sure. 

 

Will update next week. 

 

Cheers

[cal844]

Replacement module, cap and arm ordered just to be sure.

Will update next week.

Cheers

Perfect, I like the forward planning

Good luck

[Ethel]

You could put a plug lead directly on the coil and a wire on the -ve coil terminal that you can tap to earth the plug should spark when the earth contact is broken. You'll know the coil is functional - if you line up the dizzy (rotor arm) to fire a plug you can test the HT bits too.

 

If it turns over you have a decent earth. The coil's earth is via the -ve terminal (primary winding) and the plug leads (secondary winding).

 

The next thing to check would be the reluctor gap inside the dizzy. There's not much else you can test, just a few resistances on the ignition module.

[gazza82]

Just change one thing at a time .. so module first. Otherwise you will never know what fixed it ..

[nicomasala]

True, i want to do module first, as would be keen to know. 

 

Cap and rotor arm were new, but in scruffy old boxes, so never know for sure. 

 

I will also try the plug test first, as keen to know what has fooled me :)

[timmy850]

The negative side of the coil isn’t an earth that goes to the body. That terminal gets the signal from the distributor (from the points or electronic module) that it’s time to send the spark from the coil to the distributor cap

What others have suggested is to:
-Turn key to on so the positive side of the coil has 12V
-Disconnect the coil to distributor cap thick silicone ignition cable and hold the cap end near an earth (preferably wedge it in do you don’t have to hold it, you may get a shock) leave a small gap so you can see a spark
-Connect a short wire to the negative side of the coil and then tap the other end on an earth. This should make a spark and confirm the coil is working fine

Eg
https://youtu.be/rJYJ3KvPhhY

If you ever hook up the electronic module wrong it’ll fry the circuit inside

[Spider]

If you have a Test Lamp, an LED one would be best here as a filament type maybe hard to see for sure, and connect it between the Coil -ve and Earth, the Lamp (LED) should flash off briefly as it's being cranked and likewise, also try it between the Coil +ve and 12V +ve, and you should see similar but reversed as in when it was previously on, it should be off and viki-verka. If it doesn't do this, then it's likely the Distributor. If it does, then it's likely the Coil.

[nicklouse]

Did that engine run before with that dizzy ?

 

Are the ignition leads pluggedd in the correct firing order?

 

 

distshaft.jpg

That is actually incorrect for the original electronic distributors.

[Ethel]

The negative side of the coil isn’t an earth that goes to the body. That terminal gets the signal from the distributor (from the points or electronic module) that it’s time to send the spark from the coil to the distributor cap

What others have suggested is to:
-Turn key to on so the positive side of the coil has 12V
-Disconnect the coil to distributor cap thick silicone ignition cable and hold the cap end near an earth (preferably wedge it in do you don’t have to hold it, you may get a shock) leave a small gap so you can see a spark
-Connect a short wire to the negative side of the coil and then tap the other end on an earth. This should make a spark and confirm the coil is working fine

Eg
https://youtu.be/rJYJ3KvPhhY

If you ever hook up the electronic module wrong it’ll fry the circuit inside

You get a spark when the distributor (regardless of type) stops the -ve side of the coil earthing. That's why ignition points are also called contact breakers & it's not a good idea to leave the ignition on too long if the engine isn't running. Electronic ignition does exactly the same, but uses transistors to do it more rapidly to get a stronger spark. Both the +ve & -ve supply the ignition module with +ve voltage, the -ve is just lower because it comes via the added resistance of the coil windings. Whether getting the polarity reversed does any damage is unlikely, it's likely there'd be an internal resistor on the +ve to match the voltages if it was a problem. Of course it won't work as well with the polarity reversed just as clockwork ignition doesn't because you'd be supplying the secondary winding via the resistance of the primary.

[nicomasala]

Argh, changed module and cap and rotor, and still no spark

 

Any further ideas welcome please. I will get back out there in the morning. 

 

Nick