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hspeck

Engine suddenly cut off when idling

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2 hours ago, ekwan said:

Coil resistance builds up as the wiring heats up. That's why they (coil) work again as it cools down.

Its nothing to do with resistance in this kind of case, its the internal thermal switch which is either open or closed.

In the case of a coil which is causing a misfire this is caused by insulation breakdown of the wire which results in shorted turns of the coil windings. Different issue.

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1 hour ago, Andyww said:

Its nothing to do with resistance in this kind of case, its the internal thermal switch which is either open or closed.

In the case of a coil which is causing a misfire this is caused by insulation breakdown of the wire which results in shorted turns of the coil windings. Different issue.

Hmmm.......I used to work for Lucas, but admittedly, have never seen nor come across any of their thermally switched ignition coils before. If I could have a model number, perhaps I could purchase one to dissect as a matter of personal curiosity. TIA.

Edited by ekwan

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I know some do, as I have had exactly this problem before. Coil was open when very hot then OK when cooled.

The PO of the car had fitted a ballast coil without a ballast resistor. I think it was a plain black coil not Lucas though.

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My understanding of ignition coils is that the windings consist of fine copper wires. As the temperature increases, the resistance of the windings increase and current flow decreases. For a fixed dwell, the coil is unable to build up sufficient energy to sustain a spark. 

But I could have been misled with incorrect information.

Edited by ekwan

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On ‎07‎/‎05‎/‎2019 at 21:12, ekwan said:

A leaking coil overheats. The oil is for cooling. 

 

On ‎08‎/‎05‎/‎2019 at 00:44, drdoom said:

As observed by Eric the oil is for cooling. Perhaps with that gone heat could build to the point where internal wiring shorts it out?

I see, but what about the newer resin coils? the resin helps to dissipate the heat?

On ‎08‎/‎05‎/‎2019 at 02:30, Andyww said:

If the coil was a type which required a ballast but there was not one fitted, it would have overheated. This results in oil seepage and the internal thermal cutout in the coil tripping out, until the coil cools down again. This causes intermittent sudden engine stops especially when stationary, no cooling air over the coil.

 

I am not sure what coil was on the car, as there was no label on the coil.

My Esprit does not have a ballast system, so I have replaced with a non-ballast Lucas Dlb198. It seems to be holding well... but we'll see

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2 hours ago, hspeck said:

 

Resin type coils are of a different design. Like the ones used on a Lotus Elise S1. The resin is impregnated so it dissipates heat and often the heatsink is incorporated into the design e.g. Elise S1 coil.

1998096191_Screenshot2019-05-09at10_46_43AM.thumb.png.6e5f6296b30041185f4392f3f4d469e1.png

Where you have a "coil on plug" design, the coils operate at 1/4 or 1/6th the frequency of the conventional coil and there is obviously a lower heating effect.

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On ‎09‎/‎05‎/‎2019 at 11:49, ekwan said:

Resin type coils are of a different design. Like the ones used on a Lotus Elise S1. The resin is impregnated so it dissipates heat and often the heatsink is incorporated into the design e.g. Elise S1 coil.

1998096191_Screenshot2019-05-09at10_46_43AM.thumb.png.6e5f6296b30041185f4392f3f4d469e1.png

Where you have a "coil on plug" design, the coils operate at 1/4 or 1/6th the frequency of the conventional coil and there is obviously a lower heating effect.

thanks for the information

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On 09/05/2019 at 04:49, ekwan said:

Where you have a "coil on plug" design, the coils operate at 1/4 or 1/6th the frequency of the conventional coil and there is obviously a lower heating effect.

I was under the impression that coil on plug ignition systems were the "wasted spark" type where all plugs are fired, by their respective coil, together at the same time which increases the coils firing by 4 (or 6) not decreases.


Cheers,

John W

http://jonwatkins.co.uk

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Wasted spark only fires 2 cylinders at the same time, the ones (almost) at TDC, not all of them. With spark on plug it depends on the control system. If it can handle it, it can control each plug separately. Or simply things by using wasted spark, for example to have the same drivers for a V8 with wasted spark as for an individually controlled 4 pot.


I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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3 hours ago, jonwat said:

I was under the impression that coil on plug ignition systems were the "wasted spark" type where all plugs are fired, by their respective coil, together at the same time which increases the coils firing by 4 (or 6) not decreases.

Engineers' prerogative. Some use the wasted spark as a matter of convenience e.g. Elise S1, Citroen 2CV. Some use it as a pollution control measure e.g. Alfa Twin Spark engines, while others don't use wasted spark at all.

 

On the Alfa Twin Spark 16V engines, when cylinder 1 fires (main spark), the wasted spark is used to fire the smaller spark plug on cylinder 4 to combust any unburnt leftover hydrocarbons. As such, you could disconnect the wire running from the coil of cylinder no. 1 running to the small spark plug on cylinder no. 4 and it would still run fine with no loss in performance.

 

Edited by ekwan
Additional info

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So... 20 days after I replaced the coil, the car died again this morning. 

I was able to start the car after some cranking, but the car died again after a short distance. 

I managed to park it properly, and I am hoping it stays died so I can try to find the fault this time round... 

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3 hours ago, hspeck said:

So... 20 days after I replaced the coil, the car died again this morning. 

I was able to start the car after some cranking, but the car died again after a short distance. 

I managed to park it properly, and I am hoping it stays died so I can try to find the fault this time round... 

Did you place your hand on the coil to see if it's burning hot at the point when your engine stalled?

That might have been an opportunistic diagnostic move. 

Edited by ekwan

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21 minutes ago, ekwan said:

Did you place your hand on the coil to see if it's burning hot at the point when your engine stalled?

That might have been an opportunistic diagnostic move. 

Unfortunately I did not as I was rushing to work.

The car cannot be started now. I pulled the fuel line as you suggested previously and verified that there was fuel.

The sparks are very weak when I pulled the no.1 lead and attached a spark plug to check. I will need to recheck the spark from the main lead to the distributor later when I have the time. Being the 1st day of the workweek makes time a little tight today.

Thanks.

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So, I replaced the coil again because of bad spark, and the car is alive once more. This time I used a Viper coil.

The coil I replaced the previous leaking one with was a new original Lucas DLB198, not sure why it failed.

However, I have learned to not be too sure and run the car for a while before I determine if it was the coil ...

Will update again.

Thanks.

 

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Have you replaced the rotor and distributor cap? If not, you're well past due to get it done.

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4 minutes ago, drdoom said:

Have you replaced the rotor and distributor cap? If not, you're well past due to get it done.

they were replaced last november

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9 hours ago, hspeck said:

they were replaced last november

. . . . and has the cut-out issue arisen in the wake of that work in November? Recall the earlier postings from myself and others which cited the possibility of dielectric failure in new parts.

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10 hours ago, drdoom said:

. . . . and has the cut-out issue arisen in the wake of that work in November? Recall the earlier postings from myself and others which cited the possibility of dielectric failure in new parts.

yes, I will need to take that into consideration as I have experienced the new coil failing. I will monitor for a while and if it happens again the next thing I will do is to pull the distributor and check. In situ inspection does not indicate any problems with the cap and rotor arm.

 

and to add, I tried to hook up the spare powersparks distributor I have(the Ht lead and cable to coil), and hand turned the distributor, but it is no producing any sparks... I don't understand why... another new item failure??

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Might be time to step back and give all assumptions a re-think. Are you indeed certain that the coils have failed? No chance they were stricken by another failed element in the circuits? What if the high voltage output has been shorted, giving the appearance of weak spark further down the path? As to the distributor rotor I am suggesting to simply change that on speculation, as I would also the cap. The reasoning is that dielectric breakdown can occur in new parts right off the shelf whilst leaving practically no visible evidence, other than weak spark at the leads/plugs. If you retained the prior rotor and cap, assuming they had been functioning well enough when removed, they could be put back into service confident they had not changed while laying about on the shelf. Therefore an A-B comparison is achieved which should be conclusive in determining function of the current bits. It is perilous to troubleshoot complex systems or mechanisms by checking multiple items simultaneously. Isolate and focus rigorously, piece by piece, as the culprit could be one which you had not so far considered. 

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49 minutes ago, drdoom said:

Might be time to step back and give all assumptions a re-think. Are you indeed certain that the coils have failed? No chance they were stricken by another failed element in the circuits? What if the high voltage output has been shorted, giving the appearance of weak spark further down the path? As to the distributor rotor I am suggesting to simply change that on speculation, as I would also the cap. The reasoning is that dielectric breakdown can occur in new parts right off the shelf whilst leaving practically no visible evidence, other than weak spark at the leads/plugs. If you retained the prior rotor and cap, assuming they had been functioning well enough when removed, they could be put back into service confident they had not changed while laying about on the shelf. Therefore an A-B comparison is achieved which should be conclusive in determining function of the current bits. It is perilous to troubleshoot complex systems or mechanisms by checking multiple items simultaneously. Isolate and focus rigorously, piece by piece, as the culprit could be one which you had not so far considered. 

Taking a little break from bird photography and not having to rely on a mobile phone for internet.......

All options are on the table. It's important to understand how the Lucas CE system works to figure this whole thing out.

There are 3 systems that need to work concurrently in the CE ignition system, mainly the

1. ignition coil 

2. the trigger, and the

3. amplifier box in which there could be the module, capacitor or the Zener (if fitted).

All 3 components above are prone and subject to heat related failure.

A failure in any of these would reduce or eliminate HT functionality. Unfortunately, this seems to be an intermittent issue and this can be a real b**ch to track down. Unfortunately, replacement components are expensive and diagnosis (especially component purchases are made on an importation basis) on a one-for-one replacement basis may not provide a satisfactory solution. I am, in a lot of ways in the same boat so I can feel the pain. Let alone the odd wiring issue......wire connections, switches, fuses, relays, internal wire breakages etc.  😥

And for the above reasons, I am reluctant to assign blame on any one component.

I had this issue on my S3 NA, but it turned out to be the ignition switch........took me a week to figure this out, but still it p*ssed me off completely.

Edited by ekwan

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I guess the main problem is the intermittent occurrence of the fault. I can only try to change 1 item as and when the fault occurs. 

Unfortunately, other than the coil and a non-working distributor, I do not have any spares for the other parts. 

I have since order all the items I can think of for the ignition from SJ, and awaiting their delivery.. Costly, but I guess I do not have the liberty of ordering 1 item at a time.. 

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28 minutes ago, hspeck said:

I guess the main problem is the intermittent occurrence of the fault. I can only try to change 1 item as and when the fault occurs. 

Unfortunately, other than the coil and a non-working distributor, I do not have any spares for the other parts. 

I have since order all the items I can think of for the ignition from SJ, and awaiting their delivery.. Costly, but I guess I do not have the liberty of ordering 1 item at a time.. 

I would not waste any more money on parts until a more definitive diagnosis is made. Nothing could be worse swapping in $00's worth of parts and then finding out the problem still exists.

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22 minutes ago, ekwan said:

I would not waste any more money on parts until a more definitive diagnosis is made. Nothing could be worse swapping in $00's worth of parts and then finding out the problem still exists.

I would like that also, but I will not be able to identify which is the faulty part unless I replace them 1 at a time.

I did the measurements to check the voltages and resistance of the ignition parts as per the service manual, but all seemed to be fine then. I will probably need to do that again. Also to try the original Lucas coil that I removed since the resistance seems to be ok.

I realized that I do have a spare ignition amplifier, although it is a Cambiare VE520227 instead of a GM unit. can't remember why I bought this. I also have a spare capacitor for the Lucas AB14. So if it happens again I will change these while waiting for the other items to arrive.

  

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The only definite factor seems to be that the coil is overheating and cutting out. 

I think we have established the CE system runs entirely on 12V without ballast and the coil is a correct 12V coil so the only other cause of overheating is excessive dwell time (the time the coil is switched on) or the ignition is intermittently turning on the coil permanently. So this does point to the ignition module.

I am not sure about turning a distributor by hand on these systems. They dont use an optical sensor, its a coil and magnet, or might be hall-effect, cant remember, so it would be speed-dependent. Unless the shaft was rotating at a certain speed the output of the sensor coil may not be enough to trigger the unit. 

Not sure about all the various mentions of different manufacturers items above, Powerspark, Cambiare, GM. All the system would need to be the original Lucas Constant Energy for it to work properly I would think, namely distributor sensor, module and coil.

Edit: Just noticed from the thread there is a diagram which indicates this is a car which has the extra "gubbins" such as engine overspeed module. That has to be another prime suspect. 

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45 minutes ago, Andyww said:

The only definite factor seems to be that the coil is overheating and cutting out. 

I think we have established the CE system runs entirely on 12V without ballast and the coil is a correct 12V coil so the only other cause of overheating is excessive dwell time (the time the coil is switched on) or the ignition is intermittently turning on the coil permanently. So this does point to the ignition module.

I am not sure about turning a distributor by hand on these systems. They dont use an optical sensor, its a coil and magnet, or might be hall-effect, cant remember, so it would be speed-dependent. Unless the shaft was rotating at a certain speed the output of the sensor coil may not be enough to trigger the unit. 

Not sure about all the various mentions of different manufacturers items above, Powerspark, Cambiare, GM. All the system would need to be the original Lucas Constant Energy for it to work properly I would think, namely distributor sensor, module and coil.

Edit: Just noticed from the thread there is a diagram which indicates this is a car which has the extra "gubbins" such as engine overspeed module. That has to be another prime suspect. 

I am also not sure about turning the distributor by hand, but that was how it was tested for contact point distributor. I am not sure if it is the same for inductive type pick up.

The Lucas AB14 does have a GM amplifier inside, the only difference is the additional capacitor and Zener diode.

nevertheless, I have ordered the amp, rotor cap, rotor arm, inductor pickup, the wire from amp to distributor from SJ. I am not sure if they are original Lucas or not, as many of the original Lucas products are NLA. I hope that whatever they have provided will help to solve the problem if it was not because of the coil. Even if it was the coil, having these spares on hand may help in future if any of them fail...  Costly exercise I know, but I am too far away from the parts for a cost effective solution

Thanks.

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