You're welcome Michael.

I wish I knew or could check on mine, but I have the digital-P system (I would assume you still need 12V though). I'm brainstorming here, but with such low readings is this not maybe why a 6V coil was previously used? Maybe probe further back along the coil wires, you might just find something "non-standard".

 

I will check the wiring back to the ignition switch ... even when there is a ballast resistor, I should still get at least 7-8 Volts on the coil, at least that is what I have read so far ...

Have already stripped the wires on the way to the ignition switch and there is also only 2V ...

that 6V is still on my mind, but why would a 6V coil be used on a 12V car ... something is really strange about this car :-D

 

but ... it has been running before ... so it has to run now ... there is not much in the ignition system left, that I haven't checked or replaced :-)

 

I know how you feel, Michael, these cars can indeed cause a lot of confusion... One more thing you might want to check is; are you getting power to the fuel pump while cranking? I had this problem on mine, the fuel pump would prime normally but didn't get powered while cranking, this resulted in her "coughing" on a few cylinders. I have since had it "hot-wired" so that the pump runs continuously with the key in position 2 and 3 (ignition and start).

 

Hi my-key

I've no idea if you've found the problem with your car yet, but I had a similar problem and have managed to solve it... Have you cleaned out any carbon build up in the distributor? This turned out to be the problem with mine, the pins that the rotor arm passes and allows spark to jump to should be clean.

Hope this helps.

 

Hi Nathan,

I have cleaned the distributor arm and cap contacts as I was replacing the plugs, so this is done on my Daimler :-) still no change ... however, today I have found that one fuse under the steering wheel is blown - it is a 35A one and acc. to the description on the fuse box cover it is supposed to be also for some emission control or what ... however, Haynes says nothing about it, so I really don't know if this could be part of the problem ... will however replace it tomorrow, once I buy a new one and we will see ...

it is still the same, it is cranking, fuel is coming, but the voltage at the coil is only 2V and on the leads to the coil there is 7V ... so still low in voltage here and haven't found the reason why ...

I have realized that there is some "ignition protection relay" - who knows what is it used for? :-) ... it should be somewhere at the fusebox under the steering wheel, but I don't know what is its purpose ...

thx for any feedback :-)

 

On the later cars, and I strongly suspect yours as well, the ignition protection relay was to protect the ignition switch against excessive accessory load from the windshield wipers, power windows, etc. Rather than run such things off the ignition switch, they were run off a relay ....which was triggered by the ignition switch.

It doesn't have anything to do with engine ignition---coil, plugs, etc


Cheers
DD

 

thanks Doug, so this is not my way I need to go :-) so back to studying the manual ... :-D

 

Generic No start diagnostic paths.


1. Does the engine crank?


2. Is fuel delivered to the injectors or carbs.


3. Spark at the plugs?


Common thought.. all IC engines need compression, air, fuel and spark, each n the right amount and at the right time.


Anecdotal: 6v coils were used in 12 volt cars for one reason or another in various makes. !2v was reduced to 6 or thereabouts by a ballast aka resistor.


Carl

 

Hi Carl,

thanks for the reply ...

the engine is cranking and there is fuel in cylinders (wet spark plugs from fuel) ... the problem is that the spark is too little to ignite the mixture (I suppose) ... there is only 2V at the coil and so I think the coil is not able to generate a current that is high enough to enable the plugs to spark as they should ...

6/12V coil ... originally there should be a 12V coil and that is what I put there once the 6V has gone ... I still think that the 6V coil was there only to fix the car quickly ... I have run about 500 km overall with the car since the purchase, so I think it was just a matter of time when the 6V will burn ...

still don't know where I can be loosing those 12V on the way to the coil ... tomorrow is the day of removing and testing the ignition switch and the amplifier ...

 

The OPUS system used a (rather convoluted) ballast resistor ahead of the coil. I suspect that's where your voltage is going. Do you have the wiring diagrams?


Cheers
DD

 

I have disconnected the leads going into the ballast resistor and the voltage on those leads is only 7V ... so there is still some problem on the way to the ballast resistor ... I have the Haynes manual with all the wiring diagrams but no help so far ...

 

One of the wires to the ballast should be solid white. Do you have that? It should have 12v with the key 'on'. If not, I suspect a problem with the ignition switch or the wiring to the switch

A lot of Haynes material is lifted right out of the service manual. Does your Haynes manual have a section "Checking OPUS Ignition" or similar like the Jaguar manual?

Cheers
DD

 

that wire is there (the solid white one) but as mentioned before, no 12V, the maximum I can get is about 7V, but when I plug it in the ballast (or in the coil - it makes no difference where) I get only 2V ...

actually I haven't found any chapter called Checking OPUS Ignition or anything similar ... but have read through the articles that you have sent me and will make some tests tomorrow ...

I suspect more and more the ignition switch as the wiring is alright, for what I haven seen so far :-)

Michael

 

One of my favorite tests is jump 12v + from the battery direct to coil +.


OK if the coil is a 12v coil. Not so much if it truly was only a 6v coil.


if it cranks readily and fires it is track back to the switch and beyond to the switch's source of 12v.


Opening the throttle on starting an FI car will not enrich the mix, but, cranking with an open throttle will aid in clearing an overly rich condition temporarily.


Off to my toys!!


Carl

 

How do I jump test the 12V from battery + and the coil + ... what will I connect the coil - point?

sorry for probably a stupid question, I don't want to burn out something and don't know much about these cars yet :-D

 

Positive coil post to positive battery terminal, negative coil post to negative battery terminal.

You may want to check your coil earth first as well... Just a thought...

 

Not sure how well this will come up but hopefully it'll help. If the system has been changed I'm not sure if the tests/checks are still valid


Cheers
DD

 

Well that's illegible, sorry. I'll try for a better, later

Cheers
DD

 

That White wire comes direct FROM the ignition switch, and MUST have 12v in when unplugged from that stupid ballast. If you have that 7v you mention, you got a dirty ignition switch electrical section, COMMON. Easy to remove and clean, time consuming, hell yes, frustating, you bet.

The ignition coil on the PreHE V12 is a "ballasted coil" and is what we call a 6 volt coil, that runs on "about" 7+ volts, EXCEPT on START mode, when it gets a 12V ZAP to fire the beast, then when START is ceased it reverts to that 7v approx running voltage, all via that alloy ballast nonsense.

Running a 12v coil on that Opus system will give you a very weak spark. Much like a 12v bulb on 6v supply, a tad DULL. Nowhere near enough GRUNT to fire that engine. Wet plugs etc.

Time to catch up on sleep now, so I will check back tomorrow sometime.