S V6 Won't Fire, No Spark
Discussion
tvrgit said:
I think we're getting distracted here by talk of condensers and stuff, that don't have any bearing on the OPs problem.
There are two possible condensers in a "conventional" ignition system.
1. A condenser across the ignition points, inside the distributor. As far as I was taught, the ignition circuit will still work whether that condenser is there or not - it's the making and breaking of the points that builds and collapses the magnetic flux in the primary windings, that creates the spark from the secondary winding. What that condenser does, is reduce LT sparking across the Points, reducing erosion and prolonging the life of the ignition points. Modern electronic ignition systems, such as that used in the S, gave no points and no condenser in the distributor. So while interesting, nothing to do with the OP's problem.
2. A condenser between the coil LT +ve terminal and earth. These are usually fitted as radio interference suppressors. That's all they do - they don't make the engine run better, or anything. My S had a radio suppressor on the coil when I got it, but the terminal fell off the wire so I chucked it. Don't know if it makes any difference because I never listen to the radio anyway.
Meanwhile, back to the OP's "no start" problem...
As you have mentioned above, condensers have no part in all this and if you had read my post you would have noticed that I was pointing out the nonsense posted by GreenV8SThere are two possible condensers in a "conventional" ignition system.
1. A condenser across the ignition points, inside the distributor. As far as I was taught, the ignition circuit will still work whether that condenser is there or not - it's the making and breaking of the points that builds and collapses the magnetic flux in the primary windings, that creates the spark from the secondary winding. What that condenser does, is reduce LT sparking across the Points, reducing erosion and prolonging the life of the ignition points. Modern electronic ignition systems, such as that used in the S, gave no points and no condenser in the distributor. So while interesting, nothing to do with the OP's problem.
2. A condenser between the coil LT +ve terminal and earth. These are usually fitted as radio interference suppressors. That's all they do - they don't make the engine run better, or anything. My S had a radio suppressor on the coil when I got it, but the terminal fell off the wire so I chucked it. Don't know if it makes any difference because I never listen to the radio anyway.
Meanwhile, back to the OP's "no start" problem...
Edited by tvrgit on Sunday 8th January 18:30
While on the subject of condensers....Do you not have a touch of an incling that the condenser will discharge through the primary circuit when the points open thus creating a rapid breakdown of the magnetic field in the coil thus creating a much higher voltage in the HT side of the coil
You should try running a car with contact breaker ignition without a condenser wired in before posting this stuff above
What a laugh this place can be
Penelope Stopit said:
As you have mentioned above, condensers have no part in all this and if you had read my post you would have noticed that I was pointing out the nonsense posted by GreenV8S
While on the subject of condensers....Do you not have a touch of an incling that the condenser will discharge through the primary circuit when the points open thus creating a rapid breakdown of the magnetic field in the coil thus creating a much higher voltage in the HT side of the coil
You should try running a car with contact breaker ignition without a condenser wired in before posting this stuff above
What a laugh this place can be
I did read your post, I wasn't criticising anybody specifically. The point was that the whole discussion of the condenser isn't relevant to the OPs problem (even if one was fitted, which it isn't)While on the subject of condensers....Do you not have a touch of an incling that the condenser will discharge through the primary circuit when the points open thus creating a rapid breakdown of the magnetic field in the coil thus creating a much higher voltage in the HT side of the coil
You should try running a car with contact breaker ignition without a condenser wired in before posting this stuff above
What a laugh this place can be
You're right that the condenser gives a fatter spark, but all I meant was you'll still get a spark even without one.
The real laugh is the amount of "diagnose by guessing" that goes on, instead of thinking through the problem. So far, going back to the OP's problem, we don't actually know yet if the coil is even getting a supply at all...
Penelope Stopit said:
....Note, the coil does not require to be grounded, ...
I relocated my coil last year. The engine ran fine before I moved the it but as soon as I connected everything back up, no spark. After much mucking about, I earthed the coil bracket to the chassis. BINGO! it started.Check the easy things first, then work up from there.
v8s4me said:
Penelope Stopit said:
....Note, the coil does not require to be grounded, ...
I relocated my coil last year. The engine ran fine before I moved the it but as soon as I connected everything back up, no spark. After much mucking about, I earthed the coil bracket to the chassis. BINGO! it started.Check the easy things first, then work up from there.
Penelope Stopit said:
...you very likely disturbed the fault when working with the coil, ...
That's why I spent 2 hours fault checking and rechecking (as above suggestions) and not finding anything wrong. The coil was originally mounted on the engine block and I moved it to the bulkhead. After 2 hours of sodding about the only thing left that was different was what it was mounted to, so I did the earth and it worked. Don't ask me to explain. All I know is, it worked and I wished I'd done the simple thing first and saved myself 2 hours sodding about in a freezing cold garage.Edited by v8s4me on Sunday 8th January 20:24
v8s4me said:
Penelope Stopit said:
...you very likely disturbed the fault when working with the coil, ...
That's why I spent 2 hours fault checking and rechecking (as above suggestions) and not finding anything wrong. The coil was originally mounted on the engine block and I moved it to the bulkhead. After 2 hours of sodding about the only thing left that was different was what it was mounted to, so I did the earth and it worked. Don't ask me to explain. All I know is, it worked and I wished I'd done the simple thing first and saved myself 2 hours sodding about in a freezing cold garage.Edited by v8s4me on Sunday 8th January 20:24
I would have had to prove how a coil worked with an earth on the body but didn't work without that earth, I would have pulled that coil apart if need be, I don't for the life of me know how a coil with an internal short circuit to earth would work
Even if I didn't have time to inspect that coil when doing the work I would have kept it for pulling apart later
There is no way I could possibly use a coil that had a internal short circuit to earth, I would have fitted a new one
I wish I could explain to you how a coil with an internal short circuit to ground could function but I can't, I can explain most if not all electrical workings but not this baby
phillpot said:
Penelope Stopit said:
Out of interest, has anyone got a diagram of a ignition coil that has an internal connection from windings to coil body?
Has anyone a link to a webpage that shows the workings of a modern day ignition coil that uses the coil body as earth
Thank you for the post, will you kindly post a link to the webpage it came from, or did this come from a book
Edited by Penelope Stopit on Sunday 8th January 20:50
Penelope Stopit said:
I will rephrase that
Has anyone a link to a webpage that shows the workings of a modern day ignition coil that uses the coil body as earth
Now you're being fussy!Has anyone a link to a webpage that shows the workings of a modern day ignition coil that uses the coil body as earth
Found it by Googling "ignition coil diagram" , when you click on "visit page" it takes you to one of those websites that find images for you, no additional information.
phillpot said:
Penelope Stopit said:
I will rephrase that
Has anyone a link to a webpage that shows the workings of a modern day ignition coil that uses the coil body as earth
Now you're being fussy!Has anyone a link to a webpage that shows the workings of a modern day ignition coil that uses the coil body as earth
Found it by Googling "ignition coil diagram" , when you click on "visit page" it takes you to one of those websites that find images for you, no additional information.
I have now found a web link that has loads of stuff on one page and that diagram is in amongst it
I know there are modern day coils for electronic ignition that have earths to them but this has been drawn for a capacitor discharge system, I have never in many years come across a coil with a internal body earth for capacitor discharge ignition
Time to do some studying to see if this is a mistake in the drawing of the circuit or to learn how it works, I am thinking this could be for a very old system but don't know anything about it
I do appreciate you posting that image
Perhaps a post from me to Max_Torque in the techy forum will reveal all
Edited to include web link http://www.learningelectronics.net/worksheets/bjt....
You can test any conventional type of ign coil off the car, simply by connecting a live 12v to the LT + tag, then flash an earth to the - tag. Put a king lead in the HT socket, insert a sparkplug in the other end, then earth the sparkplug to the same earth as the flash earth supply.
Oh, earth is usually the -ve of a car battery.
And keep your fingers away from the HT, as it will stop your pacemaker
If the coil works, refit to car then seek missing +ve supply, -ve pulse, or clamped -ve fault.
TerryB
Oh, earth is usually the -ve of a car battery.
And keep your fingers away from the HT, as it will stop your pacemaker
If the coil works, refit to car then seek missing +ve supply, -ve pulse, or clamped -ve fault.
TerryB
Edited by Blue 30 on Sunday 8th January 22:16
Blue 30 said:
You can test any conventional type of ign coil off the car, simply by connecting a live 12v to the LT + tag, then flash an earth to the - tag. Put a king lead in the HT socket, insert a sparkplug in the other end, then earth the sparkplug to the same earth as the flash earth supply.
Oh, earth is usually the -ve of a car battery.
And keep your fingers away from the HT, as it will stop your pacemaker
If the coil works, refit to car then seek missing +ve supply, -ve pulse, or clamped -ve fault.
TerryB
I was talking about this test earlier today at our local TVR club monthly meeting - you're right, but I was saving that particular test until we confirm if the OP's coil is even getting a supply!Oh, earth is usually the -ve of a car battery.
And keep your fingers away from the HT, as it will stop your pacemaker
If the coil works, refit to car then seek missing +ve supply, -ve pulse, or clamped -ve fault.
TerryB
v8s4me said:
I relocated my coil last year. The engine ran fine before I moved the it but as soon as I connected everything back up, no spark. After much mucking about, I earthed the coil bracket to the chassis. BINGO! it started.
From the very first photo, it looks like the OP has also a relocated new coil too, so the above maybe also worth trying.Edited by TVRees on Sunday 8th January 23:13
TVRees said:
v8s4me said:
I relocated my coil last year. The engine ran fine before I moved the it but as soon as I connected everything back up, no spark. After much mucking about, I earthed the coil bracket to the chassis. BINGO! it started.
From the very first photo, it looks like the OP has also a relocated new coil too, so the above maybe also worth trying.Edited by TVRees on Sunday 8th January 23:13
I'll check the earthing, but I'd be surprised if it was this. The coil bracket is bolted directly to the fibreglass and I haven't seen any earth links coming off the bolts. The coil (old and new) also has a plastic shroud, so would that even conduct back to the bracket?
phillpot said:
The Beaver King said:
2. By 'no voltage' I mean that it isn't showing any volts on the ammeter, from any of the connections back to the battery. Starting to think a fuse....
Umm, ammeters show amps not volts?The Beaver King said:
As I'm typing this, I've just rechecked the box it was delivered in and found a ballast resistor at the bottom, hidden!!!
That could well be my problem there....
Err, doubt it, as A. you had the problem before replacing the coil and B. ballast coil will work with 12 volts (may not last too long but it will work).That could well be my problem there....
Had a problem with the ballast resistor on my Taimar once, by-passed it and drove 30 miles home with full 12 volts going into the coil
tvrgit said:
Let's try again...
Battery shows 12 volts.tvrgit said:
You need to by systematic, don't jump about guessing and replacing things.
When you say "no spark" how exactly have you tested that?
And what is the voltage at the coil +ve with ignition on? Is the coil getting a supply__? If not, then __are any other ignition- controlled systems working (wipers, indicators)? If not, check the ignition switch, or the famous yellow connector at the steering column - it's not uncommon for the ignition live connector to burn out.
Where does the red wire go? Is it "live" or "earthed" with the immobiliser on or off?
Oh, just on the off-chance, you haven't had the distributor out, have you?
There are other tests to do, depending on the results of those first checks, but you can't cover every possible permutation in a single post!
v8s4me said:
Can you clarify "voltmeter shows nothing across any of the connections of the battery...".
This is the fundamental question. What is the battery voltage? (volts, not amps)When you say "no spark" how exactly have you tested that?
And what is the voltage at the coil +ve with ignition on? Is the coil getting a supply__? If not, then __are any other ignition- controlled systems working (wipers, indicators)? If not, check the ignition switch, or the famous yellow connector at the steering column - it's not uncommon for the ignition live connector to burn out.
Where does the red wire go? Is it "live" or "earthed" with the immobiliser on or off?
Oh, just on the off-chance, you haven't had the distributor out, have you?
There are other tests to do, depending on the results of those first checks, but you can't cover every possible permutation in a single post!
Spark tested by removing the plug and earthing it off the engine; no spark.
Voltage off +ve is 0; I'm gonna run with your suggestion of ignition side. I still have the yellow connector, so I'll start there.
The Beaver King said:
Battery shows 12 volts.
Spark tested by removing the plug and earthing it off the engine; no spark.
Voltage off +ve is 0; I'm gonna run with your suggestion of ignition side. I still have the yellow connector, so I'll start there.
Good, now we're Getting somewhere.Spark tested by removing the plug and earthing it off the engine; no spark.
Voltage off +ve is 0; I'm gonna run with your suggestion of ignition side. I still have the yellow connector, so I'll start there.
So you turn the ignition on and there's no volts at the coil +ve?
Next question: do the wipers work? Or the indicators? Or the heater motor? Or anything that is only supposed to work with "ignition on"? If they all work, but still no volts to coil, then you have a problem specifically in the coil wiring. Try disconnecting the +ve wire from the coil (very important that, so that you don't get an unfused backfeed to a possible short) and run a wire straight from the battery to the coil, then see if you have a spark.
If no other ignition-controlled things are working (wipers etc) skip that test, and go straight to the ignition switch and yellow connector and test those.
I can't see the bit on the wiring diagram that says "just here is a bright yellow connector block that carries more current than it was ever designed to do and will (not might, but will) eventually burn out. Symptoms- car cranks over but won't start, but no other ignition switch controlled circuits will work either."
Yes there may be a variety of reasons for no supply to the coil - but on these particular cars, that yellow connector is the most likely culprit and should be checked and eliminated first. Most owners have already changed or removed that connection for exactly this reason.
If the OP reports back "yellow connector ok, still no supply to coil but wipers etc work" then I agree, its wiring diagram time.
But if one test can identify what is likely to be a 90% probability problem, that's simple to check, go for that first, no?
Yes there may be a variety of reasons for no supply to the coil - but on these particular cars, that yellow connector is the most likely culprit and should be checked and eliminated first. Most owners have already changed or removed that connection for exactly this reason.
If the OP reports back "yellow connector ok, still no supply to coil but wipers etc work" then I agree, its wiring diagram time.
But if one test can identify what is likely to be a 90% probability problem, that's simple to check, go for that first, no?
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