Hi I'm new to the forum and finding it very useful in terms of all the shared knowledge I wonder if someone may be able to help me with a tricky problem

I have a 1989 Daimler Double Six which is exhibiting an interesting problem, I haven't seen any previous posts with the same issue. I can't currently rev the engine past 5500 rpm. A little bit of history

I've had the car for about 18 months. About a year ago, driving on the highway the engine stopped and wouldn't start again. After much mucking around by a mechanic in the area, it turned out that the coil had failed (A DAC 6093) The mechanic replaced the coil with a generic standard (3 ohm) model and the car started again. However I then, on the way back home, discovered the car wouldn't rev past 3000 rpm, engine starts stuttering, all cylinders just like a rev limiter So once back home I did some research and determined it needed a low ohms coil so ordered and fitted a new DAC 6093 coil (for fun I measured its primary at 0.7 ohms) and all seemed to be well.

Then about 6 months later the car broke down again. After towing the car to my local mechanic they determined the ignition module had failed, they remarkably found a NOS item for $100 and replaced it. It still wouldn't start however and they then determined the coil had failed as well. So they fitted a standard coil and the car started again but on running it of course wouldn't go past 3000 rpm, so we sourced another DAC 6093 (this time I measured primary resistance as 1.0 ohm !) fitted it and all seemed to be well again.

Now I hadn't really ever tried to push the car very hard ie past 4000 rpm. About a month ago I thought lets see what the car will do. It turns out it wouldn't run past 4500 rpm, it just cuts out, not an isolated misfire and same as when a generic coil was fitted but higher rpm. This may have been an issue the whole time I've had the car.

Since then I've tried another new DAC 6093 (measured 0.7 ohms) The car seemed to be cured and I at least got it to 5500 rpm. but on slowing down again the new coil failed! it lasted 5km - I replaced it with the previous 1 ohm DAC 6093 coil and, yep, away she went. But of course back to a 4500 rpm rev limit. (Odd thing is the failed coil still measures 0.7 ohms primary but it must have broken down internally somehow as have tried it again)

In desperation I've just replaced the new ignition module with the original module which I had repaired with a new GM module. The repair worked which is great, and I can now get the car up to 5500 rpm, 1000 rpm improvement, but then the same thing happens, stuttering, rev limiting

NB The same rpm limiting occurs whether driving the car or revving it with the car stationary in P

The car should be able to get to 6500 rpm. It seems to be an ignition issue as the characteristic of the cutout varies with ignition module and with coil. I'm not sure why the DAC 6093's I've purchased varied so much in primary resistance or why they keep breaking down, though the 1 ohm DAC coil has been pretty good so far.

Any idea what might be going on here and perhaps what coil I should try next ? It could be something else I guess. I haven't measured fuel pressure (haven't got the equipment) but seems unlikely as it will accelerate like a train with foot to the floor .. until it hits (now) exactly 5500 rpm

BTW the car is a 1989 Japanese RHD build, Lucas CEI

Thanks for any help

Garry B
Wellington
New Zealand

 

Had that one also.

The quality of those DAC coils is subjective in MY opinion.

One I had here with that coil was the same. I eventually fitted a spare "2nd coil", with that DAC still in the V, as the system was originally, and away it went, redline without issues.

I use Fuelmiser CC215 coils, and I still use 2 coils. It just sits with the module in that amp. That module really works HARD with a coil primary over 1.1ohms.

Also, inside that amp, and easy to get at, is a condensor looking thing, held in place with a PK screw. Remove it, it is not needed, and since it is connected to one of the +ve terminals of the module it will cut the system WHEN it leaks to earth. And they do leak to earth on a regular basis.

 

 

Hi Garry,

I have a 6 cylinder so this could all be different, but I have had similar problems with failed coil and amp module.

I also had ignition cutting out which turned out to be a combination of dirty terminal connectors to the diode and relay modules relating to the ignition system as well as some corrosion on the 7EM ignition pack connectors on the boot wall next to the ECU. It all just added up.

As an aside, my understanding of the 'unnecessary condenser looking thingy' in the ignition module is that it is a signal suppressor so that the unit doesn't interfere with the cars radio frequencies and emit a drumming like sound through the speakers who's rhythm matches that of the engine revs.

Most often there is no interference and so the canister may be seen to be useless, but then once in a while...

Happy problem hunting.

Cheers,

Nigel

 

Nigel:


That is my understanding of the intended use of that little
tin can condensor. Ignition noise suppression. Once common on
"points and condenser" ignition systems.


It is the cable from the antennae to the radio that was once susceptible to picking up stray RF's that caused the static Most are
shielded much better and work well.


In race jalopies way back, we dumped those suppressors as
mere potential trouble.


Carl

 

Hi ... A quick update and thanks for advice

I pulled the capacitor out of the ignition module currently installed - no difference

I temporarily wired a couple of other conventional coils I had lying around in parallel with the DAC (which has 1.0 primary resistance)
- 3.0 ohm coil in parallel (combined R 0.8 ohm) - no difference 5500 rpm limit
- 1.0 ohm coil in parallel (combined R 0.5 ohm) - hard to start, ran a little rough and couldn't get above 3500 rpm

(Odd thing is when I previously ran another single DAC with 0.7 ohm resistance it seemed to cure the problem, I'm sure I got it to 6000 rpm at east, but that DAC frizzed within 5km of driving)

Checked the resistance between the wires going to the dizzy - 4.09 k seems about right

So current situation is ...

Currently have my repaired ignition module and surviving DAC (1.0 ohm) installed that gets me to 5500 rpm

My now spare NOS ignition module with that DAC only gets to 4500 rpm

It doesn't seem to like 2 coils in parallel. It seems ok with a single DAC 6093 with 0.7 ohms but DACs with low ohms seem very unreliable (Had 2 failures).

I'll see if I can get a couple of Fuelmiser CC215 coils as Grant suggests and try in parallel despite my results with parallel coils to date

I might also check resistance of the FI wire from the Lucas CEI to the ECU in the boot but seems a very unlikely culprit given the varying results with modules/coils

I do wonder about the ignition units and whether a better quality GM module (not sure how I'd source one) might do something given the quite significant differences I'm experiencing with the 2 units I've got

PS I had also previously checked the distributor advance mechanism and vacuum advance and all fine. Rotor and cap looked ok too. I didn't check the rotor gap though. Anyway varying results with ignition module/coils seems to rule dizzy out.

Cheers
Garry

 

Mmmmmmm.

I have always used Echlin (Made in USA) brand (TP45B) modules, but they are hard to find these days.

I have used a Tridon brand (TIM016) af late with no issues that I know of. That car is DRIVEN, so I would have heard by now if issues were present.

I have heard of all sorts of issues with that sucker from the guys in the USA using a GM branded module.

I am on the same thoughts as you, as quality is a no show anywhere these days.

A good coating of conductive paste is required between the module and the casing of the amp.

One other thing I am kind of mentioning coz I can. The gap of the star wheel and the reluctor point is set at 0.014", using either a brass or plastic strip to do so??.

One oher thing, I DO NOT run Resistor spark plugs in any HE, I use NGK BP6EF. The original plug is a "flat nose" style, and the BP is a "projected nose style". Always gapped to 0.025".

I also only use Magnecor brand plug leads, and have done so since 1994 without any issues at all.

After that, fuel starvation at those revs sneaks into my thought process. I will assume you still have the RH FPR fited. I strongly suggest removing it.

Then I would look very carefully at the engine strap fiasco that wraps its way around the LH engine mount. It is a root cause of many, many strange happenings on the V12 in any Jaguar. I run a battery cable size earth strap (eye to eye type) from a sump bolt to the chassis rail DIRECT, and that has sorted a lot of electrickery issues over the years.

 

Hmmmm there is no earth strap near the LH engine mount. In fact I can't see an engine - chassis earth strap anywhere. I put a voltmeter between the ignition module retaining bolt and battery earth and started it. Got about 3-5 v when starter engaged and about 0.2 v when engine running - engine was cold and didn't want to rev up too high but was steady 0.2v to 2500 rpm. I'll get a battery cable as suggested and connect between an unused tapped hole on the LH inlet manifold (right next to the ignition module) and the bolt where the battery earth strap connects to the chassis and see what happens

Thanks

 

It will be a start.

Many dont realise that the engine is rubber mounted, and the cradle it sits on is rubber mounted to the chassis. Hence the Jag 2 strap fiasco.

 

I have had exactly the same problem on my DeLorean, in which I'm using a GM module instead of the stock Bosch module. The Delco ignition modules are surprisingly sensitive to coil impedance. I ended up with a yellow Accel 0.7 ohm coil (I think it is an Accel 8145) which works with no issues.

 

Hi

Just a quick update on the high speed misfire/cutout on my Daimler Double Six. I ended up replacing the ignition coil with a Bosch HEC 717 a week or so ago and the problem has gone. The car now revs to 6500 no problem. The HEC 717 measures at about 0.5 ohms primary, is a similar style to a DAC 6093 but a little smaller and looks much much better built. It was common fitment on some Aussie 6s and V8s. My research indicated it would be a good match for a GM HEI style ignition ie as per the Jaguar V12

Time will tell just how reliable it actually is but have a good feeling about it so far, it seems to run a lot cooler at least before general engine heat soak sets in. As for DAC 6093s, I reckon they're rubbish (well the ones common on EPay anyway), variable in quality and even if you can find a genuine low ohm example, grossly unreliable

Thanks all for for your help

 

Glad you fixed it.

 

As you've discovered you have to do a lot of research to get what you really want these days.

There are a LOT of junky off-brand coils being sold out there (check out the X300 threads, for example)....far too often represented by the vendor as "OEM". With knocks-off's, global manufacturing, label engineering, and constant changes in corporate ownership it's almost impossible to know what you're really buying these days.

The original 6093 coils were made by Ducellier and worked quite well. Not sure of you can still buy a genuine Ducellier nowadays.

Cheers
DD

 

Yes couldn't agree more Doug.

And to just correct myself, the coil I'm now successfully clocking up miles on is a Bosch MEC 717B (not HEC as I stated) ... just in case anyone goes down the same path

Cheers
Garry