no spark, no start
 

hello everyone.

i have '93 daimler double six (sr-iii final, not an xj81), and it wont start.
it is a two-coiled car (has a main coil and an auxiliary one)

the problem is that there comes no spark from the coil.
i have changed so far a pick up coil in the distributor, ignition amplifier, ignition coil into new ones, and no spark yet.
i have no idea what to do anymore...

any advice would be appreciated.

Mmmm, you have been busy.

OK, Lucas ignition, so my asks based on what you have done:

1)Is there 12v to the +ve of the main coil when the ign is ON?.
2) Does this 12v remain (or close to it) as you crank the engine. My reasoning here is that the ignition switch electrical section is well documented as going hissy, and dropping the electrics when going to the "start" position. More common on older S2 cars, but the same electrical item.
3) When you mention the "pick up coil inside the distributor" I am assuming the whole shooting match with wires and grommet and again assuming NEW. My reasoning again, is that the 2 wires going thru that grommet are well known to break inside that grommet, and a bugga to diagnose. I have had a few over the years.
4) LONG shot here, so ignore if I am wrong. By "no spark out of the coil" I again am assuming you are testing with a HT lead direct out of the coil??. Reason, the carbon contact brush up inside the distributor cap has a habit of wearing away, so no spark TO the spark plugs, but still got spark out of the coil, it just cannot get to the plug leads.
5) Inside the ignition amp you will see a small condensor item, which is plugged into one of the +ve terminals of the module, remove it. They have a very bad habit of leaking to earth, guess what, NO spark. I have had 7 do this over the years.

I will keep thinking.

Grant,

Heh heh. It has almost reached the point where I don't bother reading a thread if I've seen you've already replied. Your answers/replies are always so good I very seldom think of anything to add !

I gotta admire you're experience and knowledge.

Just sayin' :)


Cheers
DD

hi Grant, many thanks for the input.

1) yes, i confirmed it
2) hmm, i didnt check that, i thought it would be enough when i check 1). i will check it.
3) yes, i did exchange the part including wires. before exchange it, i actually checked if it is not broken with a tester, the resistance was ok.
4) yes, i check the spark from HT lead put on the coil, not via distributor.
5) i didnt know that. i will remove it and check if it will start.

i will report when i have checked those 2 issues i didnt know.

oh, about 2), if the voltage drops, where should i check? should i remove the ignition key cylinder to check behind it?

Thanks maaaaate.

27 years with V12's, carby,YUK, the preHE Infected, better, HE, Pre Marelli, the best. Learnt a lot, had to. I simply could not afford the dumbness of the mechanics, or tolerate their shoddy workmanship.

They are soooooo simple in the real world, but patience HAHAHA, and a sense of humour are mandatory, as you know.

NO short cuts, ever, is my way, and those that dont understand my reasoning, I simply ignore.

Got another HE here now, the old gent continues to run it out of fuel, fair dinkum, its even got a low fuel alarm, and now its dead. Fuel pump solid molten mess, sump tank full of crap, etc etc.

:icon_beerchug::icon_beerchug::icon_beerchug:

OK, so you are loosing +ve signal in the start position?.

Remove whatever is needed to get to the back of the ignition switch. Located around the circumference is a TINY phillips screw that needs to come out. You will feel it before you see it. Once its out, the electrical section will simply pull out of the mechanical section, NOT rocket science.

CAREFULLY open up the tangs that keep the 2 section together, DO NOT seperate them yet.

Take a plastic bag, I use a clear freezer bag, put the switch inside, along with your hands, and open that switch bit up. There is a spring inside, and "normally" it stays in place, but if that sucker takes a trip across the workshop floor, the language will flow.

Clean up all the grease gunk inside it, and the pads (forgot how many) that make the contacts. Some grease it again with dialectic grease, I dont.

Reassemble it, use a OHM meter, with the Solid Brown wire as the common, and test your handy work. If its still crappy, so it again.

I am not 100% sure if the real last S3 V12 actually had an ignition relay, I doubt it, but the wiring diagram supplied with the car should indicate if it is fitted.

On my '85 XJ-S, and her S2 V12, I fitted 2 relays in the wiring loom FROM that switch. One was for accessories, the other for IGN, and that takes the real heavy load off that tired old switch, as it is now only switching ON a relay, and that made a HUGE difference to so many circuits on those cars it was almost scary.

I will look thru my many wiring diagrams when I get time, and work the next 2 days will get in the way, and see if I can find something in my library that shows something odd on that real late car, and post back as soon as I can.

I found this diagram on "Jaguarclassicparts,com". That shows an IGN relay, as #3 for RHD, and #4 for LHD.

Relay Location Diagram - Parts For Series III Saloon | Jaguar Classic Parts AU

Maybe that is the issue with your car. I know not where it si located in the real world, never seen a real late car here.

I have my doubts, as you obviously have 12v at the "IGN" position, but it drops out in the "start" position.

I will keep thinking.

Guys, could he not run a positive direct from the battery to the + of the coil and see if he can get it to start?

I would try that first just for the sake of diagnosis.

thank you so much Grant for the specific instruction.
i am sorry, i forgot to say, i have already checked the ignition relay. i heard the sound of "click" from the relay when i turn the key into the ign position. in case the relay failed, i replaced it with the same relay located in another place but that didnt work.
so i think i will have to check the ignition switch.

thank you Oliver, that is a good idea. i will try that and let you guys know what happens.

the car is at my parents house,so it may take a few days for me to start working on it.
please allow me some time to get bak here.

I went to my real house today, but have little time.
So far I only tried feeding positive directly to the + terminal of the coil, only to find it didn't work.
Maybe amplifier...?

OK.

I would seriously remove that small condensor thing inside the amp.

My reasoning is that with 12v HOT to the coil, all that is needed is a trigger to spark the sucker, and that is what is missing. That trigger is the module inside the amp, and that condensor is spliced into one of the +ve terminals of the module, so if it is leaking to earth, trigger signal is non-existant.

I am still concerned at the apparent dropping of the 12v supply in the crank position, but that 12v hot wire is by-passing that for now.

Just thinking whilst I type, scary I know. This has the 2 coil set up, so unplug the 2 wires at the main coil that go to the front coil. It will run fine on one coil, just nor rev real hard, and who cares at the moment. That front coil may be shorting and killing the signal?????.

If that is a no go, get a DVM (digital volt meter) and set it to OHMS. Remove ALL the wires from the main coil. Probe the +ve and -ve posts. You should have about 1.2ohms (so select the lowest scale the DVM has). If that reading is there, coil is deemed OK, sort of. If it is way higher, or lower, coil is suspect.

If the car has had the upgrade Ducelier coil fitted in lieu of the original 2 coil set up, forget the front coil suggestion, it aint there.

ALSO, if it has that upgrade coil, the ohms test will read about 0.6ohms.

Sounds complicated, it is not, just systematic.

Identifying the coil set up actually fitted to your car is important, as many items get replaced over the years, some good, some not so.

Many many thanks to you Greg for your advice.

Yes, the car has two coils and I also suspected the auxiliary coil, so I removed the wire from the auxiliary coil and tried cranking, still no spark.
I have replaced the genuine cylindrical coil with a lucas ducellier coil. I will check those coils (old ones and the new one) with a tester.
I think I can see the car tomorrow, I will definitely try removing the condenser in the amp as you suggested. Hope those works...

Might be a silly question. Do you have an after market alarm or immobilizer installed? I do on my XJ6 and it left me stranded the other day.

A no-start is so damn frustrating, good luck mate.

Hi Oliver, the car has few aftermarket items, just an Electric Toll Collection module and a stereo. I have the same experience on my friend's X300, though. An aftermarket security is too troublesome and I hate it!

I am sorry for not getting back faster.

I checked ignition components by a tester, then I found pick up module sent no pulse.
So I removed the dist cap and re-set the air gap between the pick up module and the rotor. I tried removing the clip and rotating the rotor by hand... then the coil had spark!
Right now the car has rough idle still, but in the mean time it started to run.
Thank you guys for all your help.

Adding to your ignition problem solving
 

I have a similar no spark problem on my XJ6 S3 , 79. Going to basics check all wires on coil have a good connection, and no loose wires on battery I have read to check HT first whilst cranking for a spark, first via (no 6) plug to engine (-ve earth). If no spark then coil lead off distributer to engine. If no spark could a a faulty HT lead (try test for continuous with a battery and bulb or voltmeter on 2 lead ends. Then look at LT circuit 1 White wire to coil is from ignition +ve on coil can be tested with a 12 volt bulb across coil +ve terminal and an engine part with ignition key in so ignition light on, as should light up bulb or show 12v on a meter. Do a continuous test that the coil -ve is earthing via a battery and bulb on -ve and an engine part, If possible check with a meter across coil +ve and -ve where there should a drop in voltage due to coil's resistance. I gather it is then usual to try substitution of the original coil for another in case it is the coil. If a HT lead has failed the energy in the coil can not earth and can damage the coil.

I have yet to understand how the more expensive ignition amplifier can influence the coil HT output for a steady stream of sparks as it 2 wires connect on the coils LT + and-ve and it other lead connect to distributer and I think amplifies the signal from the pick up (on older cars was the points). And I don't know if the -ve wire from coil to ECU matters for starting and the generation of a spark. Think the ECU matters more on controlling the fuel supply. Perhaps others can enlighten. Hope this helps.

Note after series 2 a ballistic resister was added to coil to counteract the fall in voltage/current when cranking the starter motor.

If I can add On my XJ6 I have ordered a second coil to do a substitute and to see if I need to change the HT leads. I thought it best to work on the basics before considering the distributer or amplifier or ignition switch. A - because I have yet to under stand how the amp works whether it pulse effects the coil output and B - to replace these components would be more expensive.

Hi!!!! it seems i ave the same trouble, mine is a xj40 4.0 1990. Where the ignition get the pulses? I don't remember seen any pickup coils inside the ignition. But the thing is my car cranks but don't start. any advice please ?
Many thanks!!!

Best to post your question in the "XJ40" section

Cheers
DD