Ignition Coil Wiring

[capriblu]

Please can somebody help me

My 1980 Beta Coupe has the Bosch electronic ignition.  Took coil off during week to replace with a new item as I suspected a recent hesitation/misfire was ignition rather carb related.  (Same effect with two different clean carb bodies)

The new Coil is a ballasted 6V item  with a suitable resistor.   Now car wont fire with or either new or old coil. I have checked spark from each coil and this seems good.  A spark-plug connected directly to either coil lead produces a good spark.  No spark seems to be getting beyond distributor to plugs. The cap and rotor are virtually brand new and look fine.  What started as a bad hesitation 100 miles ago has got progressively worse, only just got car back into garage from last venture out. 

Could this be the control module (would I still get spark?) or the pick up on the distributor

Any clues/help

[Neil-yaj396]

There should be 3 leads on the + terminal; 2 reds into the loom one of which goes to the carb fuel cut off, plus a black to the resistor if fitted. 2 on the - terminal; grey to the distributor and green/black into the loom. This is what Haynes says and I've just checked it against my car, although it has points ignition.

Hope this helps?

[raz1966]

my car is the same year and model, i had a week spark at the plugs, i had the dizzy rebuilt (about £100) and it ran ok after that. however the first time i drove it the coil packed up. i had fitted a new bosch coil and resistor (from ebay). once i changed the coil to the original 32 years old one it ran fine, i have also changed back to the original resisitor. i am not sure what voltage the coil is but i am sure i heard it was 9v. i think you can buy the dizzy pick ups somewhere so i would try that, i have a spare control module which works pefect. your welcome to borrow it to see if that helps. i still dont know why my replacement coil packed up (it wasn't cheap and it was a bosch).

[capriblu]

Thanks for the replies. The coil is producing a spark strong enough to get a plug to spark its just that the spark doesen't seem to get through distributor. Presumably for coil to produce a spark control module must be functioning which in turn is receiving signal from distributor pick-up? Timing/phase seems to be out somehow.    Is there anywhere that will check/repair the modules or are aftermarket units available (I see Marelli compatible system units are advertised on Ebay?) ?

[capriblu]

Eventually I decided to have distributor overhauled - used H&H Ignition Services (excellent!) who replaced original Bosch electronic trigger/control module with a neat little trigger built onto body of distributor and supplied a new coil (without ballast resistor).  Also stripped, cleaned and reset carb and car now runs better than at any time I have had it - 22 years!    I'm sure the stronger spark from the new trigger and coil has helped to eliminate slight "fluffiness" at c3K rpm under load that I never seemed to be able get rid of before. 

[droptop]

What lead did you use to fire the plug with?
If it was the coil-to-distributor lead, then there's a very strong possibility the problem is in the cap or rotor arm.
Check the carbon brush in the centre of the cap and make sure it's present and able to make contact with the rotor arm.
Also check the point of contact where the brush sits on the arm and make sure it's clean.
The module in the distributor is used to create the pulse on the low voltage side of the ignition system without which there wouldn't be a spark.
As the car's electrical system is DC, a pulse is needed to create a rising and falling voltage for the coil, which is really a high-voltage transformer, to step up to the kiovolt=range necessary to cause a spark which won't be extinguished bu the pressure in the cylinder caused by the compression of the air/fuel mixture.
In effect, what I'm saying is that if you have a spark at the coil, any or all of the following components could be preventing it from being transferred to the sparkplugs.
1) The HT lead from the coil to the cap. (If this is providing a spark to the plugs, then rule it out)
2) The distributor cap. Inspect it closely for signs of trackind betwen the electrodes and the centre carbon brush and also between any point and the edge where it sits on the distributor as this could be grounding the spark.  These usually appear as a thin black line and is usually a result of carbon residue from the brush sitting in a crack in the cap or following a line of moisture. a crack may not always be easily seen as often it,s only on the surface and not all the way through the cap.
Check externally for signs of tracking between the five £chimneys" where the HT leads attach to the cap and make sure the whole thing is clean and dry.
Also check the centre carbon brush as per above.
3) the rotor arm. Inspect it for wear as described above and also check for continuity between the outer end of the brass contact and the centre point where the carbon brush sits. It needs this path to distribute the HT charge from the coil to each electrode and onto the sparkplug via the HT (plug) lead.
4) the HT (plug) leads. These carry the HC charge to the individual plugs where the gap between the centre tip and the outer electrode creats a path for the voltage to jump thereby creating the required spark. If you found a spark from the coil via the coil-to-distributor lead, substitute it with each plug lead one at a time and see if you get a spark each time.
Finally, the obvious correct gapping of the plugs is essential as the size of the gap determines the quality of the spark.
If the gap is too litle, the spark won't be of sufficient intensity and if the gap is too great, the voltage will fail to jump the space resulting in no spark.
The setting reccomended in your car's manual is the optimum gap required factoring in the HT voltage and the type of plug.
While the whole thing reads like a long list, in reality all the checks can be carried out in a few minutes and if you find the issue early in the process, complete the procedure and check all the components as the few minutes it will take may save you a lot of hardship later.
Now I'm going for a coffee!