Hi,

new to this forum, so hi to all :-)

I have a problem with my Daimler Double Six VDP from the year 1978 ... I have bought it three months ago and it was running fine in the beginning, starting at the first kick ... now everything has worsen pretty much, as the car hasn't been starting at all, or on the fourth fifth attempt when you pumped the throttle down to the ground up to the point, when it had really rough idle, the revs were jumping up and down and finally it stalled and I had to be towed away ...

I have replaced the ignition coil, what was actually my primary suspicion, replaced spark plugs and ignition leads completely ... cleaned the distributor cap and arm ... replace the fuel pump and fuel filter ... it ran fine on that day, but after it warmed up slightly behind the half of the gauge, it starting to run roughly again and in the light city traffic I wasn't quite able to hold it running ... stood it aside, started again and came back home ... everything was fine ... on the next day however, I didn't started at all ... the fuel is coming to the plugs (they are wet after attempting to start), I can hear the fuel coming into the engine and back from the engine in the fuel return hoses ... I have a fully charged battery ...

I have also measured the voltage at the coil and here is what I suspect is bad ... originally, when I bought the car, there was a 6V coil installed ... I can't understand why on a car with a 12V system, there is a 6V coil ... replaced that with the original replacement part from Bosch - 12V ... but when I measure the voltage at the coil, I always get only roughly 2V (yes, two volts) ... I have bypassed the ballast resistor (connected the wires that goes to the ballast resistor directly to the output connector), but no change (well, sometimes it writes around 7-8 Volts, but only when I measure it disconnected from the coil, once I connect it to the coil again, I get only those 2V again ...

the engine is turning however, but it seems to me that there is no spark - coincidence with the low voltage at the coil?

I have also traced the wires that go somewhere to the ignition switch I suppose, stripped them down and measured the voltage directly on them and again, once trying to start, I get only 2V there ...

is there a way how should I diagnose the coil itself or trace the voltage drop? what steps should I undergo?

thanks for every help :-)

 

also important to mention, that when it has been running roughly, there were heavy backfires in the exhaust right under the engine ...

 

Hi there, I have had a similar problem to you, mine turned out to be a blocked fuel filter. I am back to non-run issues and have experienced backfiring, however the filter is clean. I might also add that my car was running well prior to the filter blocking, it went pretty quickly.

Let me know what you find.

Cheers

 

Hi Nathan,

well, it has to be something simple, these cars are not complicated at all ... I have started with measuring the voltage everywhere I can - on the ignition and fuel system ... I will order a new coolant temperature sensor, as I have read on many forums that it may be preventing the car from starting if faulty ... mine looks like working, but it is 10 GBP item here for me as a parts dealer, so will try it as the next step ...

some are blaming also the ignition switch fault ... but I haven't found an information anywhere on how to test it - I don't know what I should look for or what to measure on it ...

as I have replaced all the major parts on the ignition and fuel systems except of injectors, I think there is not much more in the way what might be wrong ... hopefully someone will give us a clue on what to look for :-)

and similar to yours ... my car was running nicely, starting at the first kick, pretty quick it was ...

wishing you a great day from the Central Europe

 

Many thanks, as for checking the CTS you can check the ohm reading through it, this should vary with temps. Another idea is to check the reading back at the ECU (pins 5 and 19). At 0*C it should be roughly 5900 ohms, at 10*C it should be about 3700 ohms, all the way down to about 250 ohms at 90*C.

You can also check the ohms through the coils, you should get a reading of about 0,9 to 1,1.

Hope this helps, I am on a learning curve myself.

 

ok, so to clean the terms :-)

I have a coolant temperature sensor with two pins (as stated in the Haynes manual, p.91) on the left bank (looking from the rear of the car) ... that one fitted is 0280130014 Bosch ... have tested this one - disconnected the leads and put the ohmmeter leads there but no reading has been observed ... (just to make myself sure I am not doing anything wrong, I have tried to apply the same procedure on the air temperature sensor that lays just close to this coolant temp sensor and I have measured about 770 Ohms there ... so has the CTS really gone, when I can't read anything on it? tested it when I replaced the sparks recently and I was able to read the values as stated by Nathan and as stated in the Haynes manual ...

on the right hand bank I have a thermo-time switch ... 0280130212 Bosch

and next to the thermo-time switch there is another sensor that supposed to me coolant temperature sensor ... I haven't found any part number on it however, it is brushed away ... this sensor has only one pin

moving slowly forward :-)

 

and I forgot to add that I have also tested the coil now and I am getting resistance about 2 Ohms ... so what is wrong? :-)

 

I am presuming you still have the original OPUS ignition (that is, nobody has converted it to an aftermarket type---which isn't unheard of).

You might have to wait fro Grant to come back from vacation as he's the only regular on these boards who knows that system


Cheers
DD

 

Here's some info on the OPS ignition that might help

V12 IGNITION SYSTEMS / AJ6 Engineering

Reopus Ignition | The Lucas OPUS wiring diagram + repair hints.


Cheers
DD

 

thanks Doug, will check it

 

Remember these cars do not pump fuel like an American carb as they have no primer pumps. Electric pump is primer and a manual or electric choke. Pumping accelerator to start is nil. Check fuel flow and electrics as Doug mentioned above.

 

actually, in the last days before I replaced the plugs, I needed to pump the accelerator to start ... I know, I haven't put any fuel into the engine by doing this, but when it fired finally, I had to press the pedal down to the ground to keep it running ... after that the engine has run quite nicely on idle ... definitely something wrong with the electrics I suppose as the fuel is coming to the engine (haven't tested the pressure just yet) - the plugs are wet from fuel after cranking ... but that low voltage at the coil seems really crazy to me ...

 

The coil sounds suspect... Unless I am missing something...

I had a problem on mine that I couldn't get a reading from the CTS either due to surface corrosion, make sure that the contacts are all in good order. You should be able to get some reading off it, if they fail they often fail in a certain position. You can also "fool" the ECU by bridging the plug out with wire across the 2 terminals, the ECU will get a signal that the engine is stone cold and may aid starting, but will be getting excessive fuel if allowed to run warm like this.

This is knowledge that I have gained on this forum (thanks Doug!), I wish you luck.

 

strange is that when I got the car, there was a 6V coil installed ... this 6V coil has gone and I had to be towed away ... however, I replaced it with a 12V coil ... can't figure out why there was that 6V coil ... so the coil that is installed now is new (the engine has run only three or four times after I installed it - mostly on idle, only once I took it for a drive - 15 km or so)

 

The 6V coil could have been a bodge job to have the car running... If the plugs are wet then I would suspect ignition... Does she 'cough" on a few cylinders or is she totally dead? If she has suddenly died completely it could be the ignition amplifier... A test to see that she is sparking at all while cranking could help us in the right direction. Also note the colour and size of the spark. A last question, did you ever run her at high RPM or accelerate her to a fair pace? If so was there any hesitation?

 

that is also my opinion, that it was a quick fix for the car to run again with the 6V coil ...

the plugs are wet, the fuel pump relay is running as well as the pump itself (about 1 or 2 seconds after I turn the key to ON

well, actually it does cough sometimes, but only once or twice and then it dies completely and cranks only ... more and more am suspecting the amplifier, too ... however, I don't know how to test it ...

we have looked if there is any spark at the plugs and to be honest, the spark wasn't large enough according to our assessment ... still, there is a low voltage at the coil, so maybe the coil is not able to develop a voltage that is high enough to initiate a spark that would ignite the mixture in the cylinders ...

I have replaced the plugs recently, gapped them correctly ... so they are absolutely new ...

actually, I had no chance to run her on a longer trip or to test her on performance, so no, haven't reached higher RPM ... well, not higher than 3500 or so ... but it does hesitate also in low RPM when the problem is coming and I have to press the pedal hardly to keep it running ... after that some backfires appear in the exhaust under the engine and it usually starts to run nicely again ... well, usually :-)

 

I'm not an authority on the old OPUS system, but.....

Over a period of years the system was updated a couple times *plus* some of the replacement parts were 2nd or 3rd designs....which required replacement of other parts to work and/or minor re-wiring to work. So, decades down the road you might see what appears to be a mis-match of parts.

Or something like that.

Cheers
DD

 

well, that is a positive point before weekend, Doug :-D ...

will have to go through the whole ignition system and its wiring ... but more and more I am inclined to the amp fault and so maybe I am in the need of buying the REOPUS :-D but hopefully not and it will be something more simple ...

Michael

 

If everything is sparking, check that the coil you have is the correct spec... There was a coil change in the model's life (as stated in the Haynes workshop manual on page 112). The ohm reading of 2 ohms is still concerning me... Maybe check the part number on the coil you bought and see if you can find what the reading should be for that particular coil on the net.

Just a thought

 

will check that, thx Nathan ...

however, there is still that low voltage on the supply leads to ballast resistor and from the ballast resistor to the coil ...

to the ballast resistor there went 7-8V and behind the ballast there was 2V ... all in all it seems very low to me ...

some are also blaming ignition switch, but I don't know how could the ignition switch lower the voltage in such a way ... maybe some shortage in the way?