Pertronix Ignitor Quits When Hot

[jyorkster]

1978 Spider with original Marelli S144CBY distributor. I just changed the points to a Pertronix Electronic Ignition (MR-LS1). Car started and ran fine after adjusting the timing. However, once the car heats up, the ignition just quits. Testing at the coil shows no spark. I thought maybe the coil had overheated, so I swapped for a known good coil with the same result. Car runs fine until it warms up, then dies completely with no spark until I let everything cool down.

Coils have internal resistor and both check good at 3.7 ohms primary, between 8-10K secondary. Car was running before swapping to the Pertronix and this was the only change I made.

Can the ignitor overheat? If the ignitor is bad, would it fail completely or display these symptoms?

Any help would be appreciated.

[So Cal Mark]

typically that style of ignition module can quit when hot, then work again when it cools off. Was it mounted in dielectric grease?

[jyorkster]

I did not use any dielectric grease.

Also, the ignitor plate holes did not perfectly align with the base plate that I removed the points from. I found a single hole that worked enough to hold it in what appeared to be the right location, but the instructions do not have a gap measurement. This model does not use a magnet sleeve.

If this is typical of this module, why do so many people speak highly of them? Is there a work-around to keep it cool?

I'll try to contact Pertronix tomorrow to see if they can provide any insight. I'll pass along what they tell me.

I may just be going back to the points...

[spider2081]

I think some photos of one properly installed Pertronix pic-up might help here. Does anyone have any???

[jyorkster]

I spoke to Pertronix tonight after about an hour on hold. He told me to check the following:

- Ensure I'm not using solid core spark plug wires--I'm not.
- Test with Tac wire removed from negative side of coil--Same result.
- Double check that the adapter plate is well grounded--It is. I checked this before and after warming the engine.
- Test voltage at positive side of coil under load--Tested over 12v both before and after warming engine.

It was pretty cool out tonight when I ran the car, so the engine didn't even really get that hot. After the car died, I removed the distributor cap and the module was warm, but not burning up. It may simply be a bad module.

Looks like I'll have to call again tomorrow to get a return authorization to have them send me a new module to try.

[jyorkster]

Final update--Pertronix sent me replacement module. The return was fairly painless. Now the new part is in and so far everything seems to be working fine, although I'm hesitant to test her too far from home.

As long as it keeps working, I'm happy with the change. It will probably be next spring before I get to drive enough to gain some confidence back. So for anyone wanting to make the switch, it's a simple swap as long as you get a working module.

[TStark]

That's typically how they fail.

One can use their product to trigger a spark box, high energy or msd. This way their igniter sees a fraction of the current it would normally and promotes it lasting forever. Plug you get a hotter spark, because the igniter itself is just a points replacement.

[hayesbd]

I know this is resurrecting an old thread, but I also have just had a Pertronix module go bad after only 2 months of use. I had some worn out old points and rather than replace them, I thought I would just go ahead and install something more trouble free (or so I thought). When driving back home with 125 miles to go, the car suddenly started to buck and wheeze and then regain its composure briefly, only to quickly repeat the problem. Problem was worse at 70mph than when I later turned off to side roads, but I almost did not make it home. At one point, it got so bad that I pulled over and took a peek at things for a few minutes and decided to replace the distributor cap in case there was some internal tracking (just a guess). It started right back up but quickly returned to its former behavior. Interestingly enough, it gradually improved as I drove into colder and colder night air, so I suspected a potential temperature-related problem. Playing around in the driveway with the cool temperatures lately also seemed to improve its function, but the engine was still missing badly.

I went through a long list of suspect things this past weekend and decided to pull the Pertronix and install a new set of points and voila!, the car is running better than ever. I may talk to Pertronix about a replacement module, but at this point, I would need two of them (one for the distributor and one for the glove box) in order to be comfortable on long trips. Unlike a lot of folks driving these cars, I regularly drive it on a 500 mile round trip for my job and at this point, I would rather have something I can file, tweak, and get back on the road in a few minutes than have a Pertronix be the sword of Damocles hanging over my head. At least points degrade somewhat gradually and predictably.

To be completely fair to Pertronix, the Marelli coil checked out at 2.8 ohms and I figured that was close enough to 3 ohms to be okay. Apparently not. So for those of you using these, I recommend changing your coil to be within their requirements for sure.

Just my $0.02 and I hope this helps someone contemplating this change...


Brian

[spider2081]

Another thought.
I was working on a couple of boats using Pertronix pickups with intermittent issues.

In both of them I found the units to be voltage sensitive. The pick-up requires at least 10 volts in order to operate properly. One of the units was installed with the ballast resistor still in the circuit lowering the voltage to the pick-up Wiring the pick-up per the instructions fixed the problem. The other was a faulty pick-up it became erratic when operating at 11 volts. I was able to make it work by installing an ignition relay powering the igniter directly of the alternator. Pertronix replaced that igniter but my friend thought the relay was a good idea and left it in the circuit.
Ignition coils do get hot to the touch when operating properly. I think that is why the later Spiders coils are mounted in a heat sink. The lower the primary resistance of the coil the more current it will draw and the hotter it will get. To dissipate the heat coils are often filled with an oil.
Bottom line is both the coil + and the red wire for the pertronix need a fairly constant 12 + volts to operate properly. Boor connections or a poor ignition switch can contribute to their errattic operation.