I have started many cars while working on them with a supplement charge on the battery. The charger even has a “start” circuit on it. I believe what happened is my helper turned it to “start” for too long!

 

will do! I don’t really understand why this is happening however. The previous owner just recently put a new cap and rotor in? The wires need replaced, but the test I performed was with a new wire. I have ordered the new parts already and will update when they are installed, but is there anywhere else I should look for spark loss inside the dizzy? (Since it’s good out of the coil)?

 

As the coil exit is good, and the spark at the HT lead plug-end is bad, logic dictates (Ha says the Prince of Darkness!) that either the cap, rotor or HT leads are faulty. Do NOT forget to renew the coil to Dizzy HT lead. In theory (!) this renewal should cover all possible eventualities.
Things that can go wrong between the coil exit and the plugs are: The carbon terminal in the inside centre of the cap can fall apart (point by courtesy of the Great XJS Prophet Grant Francis - please turn and bow to the Southern Cross at the mention of his name). Or the rotor can be bad, or the 12 terminals in the dizzy cap can be bad, or the rotor can be not seated properly so it is not opposite the 12 posts, or be the wrong type, the HT leads can be bad, or the plugs bad, etc etc etc.
Fingers crossed for you
Greg

 

AND,

The quality of parts these days is suspect.

The rotors CAN leak the HT voltage through the rubbish insulation material they are made off, direct to the distributor shaft.

Sadly, picking good from not so good, is almost impossible, even for us that have lived with these beasts for too long.

I have used Echlin brand, made in the USA. EP64 and EP65 are the cap and rotor part numbers, but I forget which is which, no matter, you need both.

Look at the "burn" marks on the 12 HT internal posts of the old cap. They should be at about centre in the vertical plane. Some have had these marks right at the tip of each post, NOT good, and will reduce HT intensity considerably. I had to leave the cap gasket off mine to get that cap/rotor arc height where I wanted it. No harm done by omitting that gasket.

 

i will look at this today! It’s very hard to determine though since the cap was brand new from PO and has not run with this new cap yet! I will definitely do all of the HT plug leads and the HT coil to dizzy lead, though when performing my test I used this lead and it was successful. The “break” is happening somewhere in the cap, rotor, plug leads, as you mentioned.

I was was unaware however that I could remove the gasket! I will look into that today.

Just wanted to make sure my theory is correct here though. If I do indeed get 30 Kv or so from the main lead wire from the coil, I “should” also get that same Kv reading at the plug leads as well? Or should there be a drop? The instruction on the device seem to imply that a GM module should produce 26 to 30 Kv at the PLUG. Just want to be sure I’m getting that at the plug before it all goes back together..... again!

 

Yes, the voltage at the plug should be about the same. The amplifier does not produce the spark, what it does is switch the coil, thereby timing the spark that the coil generates..

 

++ to Greg again.

The coil is "switched" by the module, as versus contact points of old, thats all the module does for the sake of this spark question.

I have NEVER measured the spark voltage, always had a good eye for that, and some fool to hold a lead whilst I cranked the engine. The distance they jump determined the OOMPH of the coil, simple. Its OZ mate, and there is always someone that will hold things for a beer or 3.

There will be a slight reduction out of the spark plug lead. The spark from the soil must travel through the carbon brush, done the brass strip, "jump" the air gap at the HT post in the cap, and then travel down a resistor OLD lead to the plug, where it must jump again a gap. A Blue Crack at the coil lead is a good thing, and that is pretty close to what to expect at the spark plug. I ALWAYS use a NEW spark plug for this test, its just easier than messing with an old burnt sucker.

I think it has been mentioned somewhere, but the engine earth strap/s need to be better than maybe, or you are chasing rainbows. Run another earth lead, simple and quick, and then tick that box off. I ran 2 battery cable spec earth cables on all mine, even the NEW S Type things, and the difference that made to all sorts of electrickery was surprising, even for me.

This is also good reading.

Electrical theory as per Joseph Lucas.doc

 

Sorry I have not been able to update, I am still waiting on a dizzy cap. Does anyone here know Brian from V12performace.com? I placed an order but have not heard from him. No return email or phone call?

 

Sorry. Best go ahead and order another. You never know about Brian, it may come one day.

 

UPDATE!!
shes alive! Kind of.....
- got the new rotor, cap, and plug wires.
- replaced injector rubbers
- replaced throttle bushings
- new plugs (gapped properly)
put everything back together, and she started and ran, although a little rough. Tried to rev to 3000 rpm with vacuum advance unplugged and capped, but it would not rev above 1000 rpm. Tried adjusting dizzy - still wouldn’t go above 1200 or so. Placed timing light on plug and it was intermittent. Spark was not consistent.
just for kicks, I put the old (2 coil) setup back on... and vroooom vrooom, it revs up fine.
So I assume my brand new replacement single coil from rock auto was bad?
Also, even though it revs now, it still feels like it might be missing, it is a rough idle around 650 to 800 rpm. It doesn’t seem to be going up and down like the AAV would cause, it’s just rough like I’m still having an intermittent spark issue?
i have replaced the GM module in the amplifier, however I suppose it could be bad just like the coil appears to be. Any suggestions on smoothing idle?
I have set the throttle bodies to .002, I have synced the linkage, I have tested the TPS.
i will link a video showing the Single coil missing with a KV tester.

 

 

OK, spark is iffy at best.

I use an inductive timing light, and the flash is a consistent thing when all is sweet.

Coz my memory kind of sucks at times, you have removed the small condensor from the amp innards??????. If not do so.

Failing that:

There is a definate misfire in both vids.

With it running, unplug each injector, one at a time, and note the cylinder/s that do nothing to the missing. I reckon you got 2 cylinders out of the system.

It may NOT be the injectors, but it is an easy, safe, place to start. My PreHE was a mongrel for fouling plugs, and injector plug pulling to locate the dud cylinders was safer for me than grabbing a plug lead, ba&^%$ds always BITE.

It will be spark, or injector related.

You are sure the distributor is in the right position. NOT doubting, just throwing suggestions out there.

Most common HT lead issue with these is 6A, 6B, 3A, 4B. Then the 2 #1 leads tucked behind that a/c compressor are always under stress.

The disappearing of the spark as you rev it slightly has me thinking Module??

 

is that video with the old coil?
Greg

 

YES. Sorry if that was confusing. Those videos were with the new (single) coil. I will post a video today that shows it with the old coil. It will rev with the old coil installed, but still seems to miss and idles rough.

 

Man that sounds familiar! Same song my 86 sings.

My current villian-du-jour is the pickup. I'm going to go re-gap it and see if that helps. I've already tried the module. Do the pickups get tired?

Just for reference, I'm running a Jaguar branded single coil replacement.

Does your spark become consistent on the tester at a lower gap setting?

 

It seemed to get a little more consistent. But would still miss. After installing the original dual coil, I took her around the block and it would only get to about 4000 RPM and then start missing very bad. I’m currently having my module checked (again) thinking the new bad single coil may have ruined it. Not sure where to go from here if it tests good? Maybe another new single coil? It’s obviously a spark issue. Just can’t seem to pinpoint where however. I did notice upon rev that if I put the inductive test light on the main coil HT lead, even it would sputter, which makes me think it’s the module.... but it seems to be testing good (at the store now)

 

Which is a typical symptom of a failing secondary coil


I wonder how it is being tested.

I worry that it might be a pass/fail sort of thing that might not reveal a subtle failure or anamoly

Lots of junky parts being sold these days..... and even a premium brand can suffer the odd dud in the bunch.

Do you have a meter to check the primary and secondary resistance of the coils?

Cheers
DD

 

Yes. They both test at .6 Ohm on the primary, and around 650 Kohm on secondary on both coils unhooked. Which is why I originally replaced them, because I have read that they should read 1.2 ohm?
I am going to post a video showing it start to miss and shows the rough idle

 

Here are two videos showing the rough idle and miss at higher rpm. I did put in a new control module even though it tested good, seemed to run a bit better, but still missing. Also I noticed that the B bank intake really sucks a lot of air but the A bank intake doesn’t? Not sure if it’s related or not.
Also, it appears my alternator may not be working as the battery does not go to “on charge” while running and is at the very bottom of the charge meter.

another note: voltage at the coil while running was 11.6 on the +Ve and 10.6 on the -Ve of the main coil. When checked across the battery itself it was 12.3

 

Normal, no worries


You might be on to something.

When running battery voltage should be about 13.8-14.3 volts. And voltage to the "+" post of the coil should be the same or close. Not sure about the "-" side of the coil when running.

When testing with engine off both coil posts should be the same and no more than 1 volt lower than existing B+ voltage.

Do you have a fully charged spare battery that you could connect to your existing battery with jumper cables just to see if increased system voltage makes a difference?

Also, just for the heck of it, have you checked engine grounding?

Cheers
DD