I have a question on my 1986XJ6. I have the constant energy ignition system coil part number DAC3001 with amplifier DAC2087. I know my distributor is electronic considering I have a cap with screws and now have physically seen the amplifier. Currently, I have the occasional misfire and rough running that I’ve been trying to track down in the Jaguar parts book. It says nothing about a ballast resistor for my ignition system. Yet my car has a ballast resistor mounted on the side of the coil. I was considering upgrading the distributor to a Pertronix electronic ignition only to discover that I already have a factory electronic ignition system I’ve attached a photo of the parts book where you can see it says nothing about a ballast resistor however I’ve also posted a photograph of my car. You can see that I have a ballast resistor. Can anyone explain this? Is it possible to bypass this ballast? How will that affect it?

No mention of a ballast resistor

A ballast on my car

My distributor

 

Depends which edition catalog you have

This illustration shows the resistor



The ballast resistor thing has caused some head scratching over the years but a constant seems to be that all later cars had it, after VIN 421xxx (I can't remember exactly). A different ignition amp was part of the change although I suspect the difference must've been subtle

Some guys remove the resistor and toss it in the trash; they're somewhat prone to failure.

Cheers
DD

 

Doug I’m still so confused. Which coil should I replace mine with? Will getting rid of the resistor cause issues or will it improve the way it runs at all?

My car is 449340 production date 02/86 my parts book is August 1985

this resistor is not available I assume it came preattached to the coil which is why they aren’t available separately but I’m not sure what should I do? What coil can I use?

 

Removing the resistor will make the engine run better if the resistor is failing. Otherwise, no change.

I'm not aware of anyone presently selling the original type coil with the resistor attached.

I've had good luck with the Lucas DLB198 and DLB170

Over the decades the coil numbers have changed many times and some of the substitutions are different spec than original or flat-out incorrect. And....some of the listings don't list the correct specs! Confusing as hell. But over the years I've concluded ...mostly from what I've heard from others....that just about any 12v coil with about 1.0 ohm primary resistance will work OK.

Personally I'd go with the DLB170. It's actually V12 coil but it worked great on my Series III XJ6 and a couple others that I worked on over the years.

Cheers
DD

 

Inside the amplifier box is a GM HEI ignition module, those are also prone to failure as they age. You can open up the metal box and replace the amp with a 4 pin HEI module. Use only the AC Delco replacement, part D1906, as most of the aftermarket ones are inferior to the GM original. You'll see it less on a 6 cylinder, but on the V12 cars it pushes the module to it's limits.

I personally would stay away from Pertronix, it is designed as a replacement for points, which you don't have. The Lucas/GM system is superior. I have known a number of people who have been left at the side of the road with a Pertronix.

 

does this mean I would use the DLB170 or DLB198 without a resistor? Or do I need to add a resistor to this coil? Is it possible to damage the amplifier if a resistor isn’t used?

 

This is great to know. I’m curious what are the signs of a failing ignition module inside the amplifier? Thank you for the advice on Pertronix. I would definitely like to keep my system as it is. I just want to get it working as well as possible.

currently I’m dealing with a idle issue (which may be part of the experience) not to turn this forum into the already heavily discussed S3 idle issues but I’d like to do what I can to smooth it out and increase long term reliability.

 

Use either of those without a resistor

Cheers
DD

 

The most common failure mode is the engine conking out on a long drive.... and then restarting OK after cooling off for an hour or two. By "long drive" I mean an hour or more.

Coil failures often follow the same pattern.

But either can fail at any time.

Cheers
DD

 

Ok thank you! Do the 2 wires leading off the ballast just go directly on the coil by using one of those double prong connectors?

 

This (photo below) is the part you’re referring to? This is inside the amplifier box? I am not having issues, but I may replace it for good measure. Are there other parts of the amplifier that can fail or just this component? How do you open the amplifier? Is it held together with screws?

thank you!

 

Yes, that's what I am referring to, I can't remember how the metal box was held together, but it wasn't difficult to open. I usually get my parts from Rockauto, they have excellent prices. There are many counterfeit parts out there too, Rockauto doesn't sell that.
https://www.rockauto.com/en/moreinfo...t=7172&jsn=323

 

I am unable to locate a DLB170 I assume the next best thing is a DLB198 ohms 0.8-0.9? So I’m going to go with that and dispose of the ballast. Unless there’s another coil I should consider .
what is the actual difference between DLB 170 v 198? How will the car perform differently between the 2?

 

thank you very much for this! I will swap it

 

DLB198 0.8 - 0.9 ohms is fine, you would not be able to notice the difference between the two coils .. getting rid of ballast resister is where you may see an improvement with a more stable idle. Modern production of Delco Ignition Modules have internal components that are more resistant to high current fluctuations without failure, than New Old stock units. You should order a spare for your shelf now, as if you go to an auto supplier on a Saturday, they will have a knock-off in the store, but will have to ship in the Delco brand for Monday delivery.
Rgds
David
Thread with more details, if you decide to open up ignition amplifier and replace module
https://www.jaguarforums.com/forum/x...epairs-210475/