Rough running once warm - need to replace some of ignition parts?

[twobone]

I think aspects of my ignition may need replacing. It is an original set up from the late 80s from Caterham. There is a Lucas electronic box that is mounted to the firewall that is connected to the non-vacuum advance distributor.

 

Particularly after about 30 minutes on the road, I'm getting rough running and hesitation. I just find the engine sounds harsh and there is poor acceleration. I have the carbs well tuned in so I think the ignition system is not operating properly.

 

Perhaps I should just start with replacing the cap, wires and coil now that I have new spark plugs installed.

 

Any advice is appreciated.

[turboeric]

If it were a Miata motor, I'd say you need to do plugs and wires.

[pi7ot]

I would check the static engine timing as well, plus fuel pressure and delivery specs.

An air/fuel ratio monitor would be a good tool in order to find out whether the fueling remains too rich after warm up(coolant temp sensor failure) or too lean (insufficient fuel quantity/pressure).

 

m

[scannon]

Does the coil get really hot to the touch about the time the missing shows up? It or the electronic box could be getting heat sensitive with age (or other problems).

[twobone]

Skip I think you hit the nail on the head. The old Bosch coil was screaming hot. I replaced it with a coil from the local auto parts store. I hope to take her for a drive later tonight to test the fix. It now makes total sense as the deterioration after 30 minutes of driving was very pronounced.

[Ian7]

Skip I think you hit the nail on the head. The old Bosch coil was screaming hot. I replaced it with a coil from the local auto parts store. I hope to take her for a drive later tonight to test the fix. It now makes total sense as the deterioration after 30 minutes of driving was very pronounced.

 

Twobone - not to squash your enthusiasm, but your problem identical to one I had, right down to the too-hot-to-touch coil. New coil fried only days later.

Traced it to a poor battery that wouldn't hold a charge....

 

At least I believe so, no issues since I bought an Odessy...

[twobone]

I'm equally worried. The new coil is really hot. How hot does a coil normally get?

I've never had a problem with my battery.

[twobone]

crap that was dumb. The Bosch coil I replaced had a built-in ballast resister. The $50 Accel coil I just bought does not. Guess I'm asking for trouble...back to square

one

[scannon]

Coils do get warm but generally not so hot you cannot touch them. If you ran the Accel coil without a ballast resistor and the circuit to go with it you are asking for trouble.

[twobone]

The internet is an amazing tool.

 

I managed to find a wiring diagram for a Lucas type electronic triggered ignition that is similar to the one on my car. Lo and behold it shows that the coil needs a ballast.

 

Thankfully NAPA can get me a proper coil. Hope to have it installed and running today. We have a day long Lotus club run on Sunday and I really don't want to be stranded!