75 L-jet 1911cc engine. Last problem was solved in May I believe. I have been putting miles on it pretty regularly since then.

Some folks may remember that I had an internal backfire and bent my AFM. The backfire came from a massive vacuum leak at the TB seal. I had just had the TB rebuilt, but did not replace the seal and did not install it in the same orientation as it was before. So there were depressions on the seal. Anyway. My smoke machine found the leak, plus a few more. Sealed them up and installed a new AFM tuned to the 1911 and all was well.

Fast forward to this week. Wednesday driving home from work, just entering the interstate and I got a big hiccup. Felt like the engine died for a brief second as I was shifting. Kinda like the jerk you feel when you are jump starting the car by popping the clutch.

made it home and did not drive again 'til this morning. It happened again. Then again, then really bad spitting and sputtering on acceleration. It idles fine tho. So I turned around and went home. Smooth ride home to get another car, thank goodness.

I have an on board Air/Fuel meter that I have been monitoring. All this happens so quickly, I just don't have time to see the meter.

1/2 a tank of gas, just e10 87 oct, but it could be bad. But the 1st 1/2 was fine.

I figure if I can this weekend, I'll breakout the smoke machine and see it I have another vacuum leak.

Any other thoughts.

Fuel filter, crap in the injectors, failing fuel pump. Most likely fuel related as ignition issues usually stop an engine cold.

Intermittent issues are hard to chase. Perhaps you could stick a Go Pro camera in the engine bay, pointed at your fuel pressure gauge as you drive to work?

That would be good. But I don't have one. And kinda worried about driving anywhere. But my sweet talking to the car got me home. I'll see what rev'ing in the garage tells me. You don't think it's a vac leak?

I did some removing and reinserting of hoses prior to this video. Which does not seem to help. My guess is that it seems to be gulping some extra air, hence the LEAN reading. Then as things warm up, things get sealed up and she runs normally.

This video shows something is going on ..... you see and hear it at about 45 seconds. The engine does not want to idle. My engine bay fuel pressure gauge is at 35 psi during all the hiccups. So the pump is good.


https://www.youtube.com/watch?v=lnYWgePMNVQ


I brought out my clip on RPM gauge and tinkered with the idle. Got it back to about 950. Got in the car and drove around for 20 minutes. No hiccup at all. Well I know you can't just keep adjusting the idle screw so I am gonna break out the smoke machine and see if I can find a leak. It really seems to be a leak problem.

FIXED.... I think, I hope. Here is the deal. I have a fuel pressure gauge in the engine bay. steady at 35 psi, never wavers. So the Pump is good. Not yet checked for vacuum leaks, but don't think I need to now. So here is what I did with help from Doctor L-Jet.

He had me attach my timing light. It is inductive, so very easy to run a test on each cylinder. I pointed it at the trunk and revv'd the engine hoping for the intermittant problem to show up and it did. On every cylinder the timing light blinked. Problem has been narrowed down.

Next I jumped the Coil+ to Batt+ and got the same result. So Doc said the relay board was good.

Now I am down to ROTOR, CAP, CENTER WIRE or my HOT SPARK.... I don't have points.


https://www.youtube.com/watch?v=MvjUhiUBH7U

Hot spark module replaces the points and condenser. $50 and it looks like it lasts about 38000 miles. I had a spare, so once it was installed, I could not make the timing light blink. I think the Doc has cured my hiccups. Thanks again. Guess I better get another spare, or think about going back to points.

Link for 914 hot spark

Click to view attachment

Interesting cure.

I would still check for vacuum leaks.

Tim thought the module "looked funny". The red plastic on the module had faded. Kinda looked white. The modules come with a white goo to apply between the base plate and the module. I assume it helps with temp. Tim suggested getting a different goo, arctic silver. So I am gonna do that.

Even the screw that held the module to the plate was too hot to touch after all the troubleshooting revs. The rubber grommet that holds the wires was brittle from heat, no doubt. Again, almost 40000 miles. Lots of them cruising the interstate on 6 hour trips.

Just checked out the hot spark website. Lots of talk about over voltage, nothing about a HOT disty. They sell a recommended coil and a ceramic ballast resistor. I bought it all for about $85.

If it rains tomorrow, I might get the charcoal out...

I'm running a Pertronix Ignition module (Ignitor II, I think). Sometimes I'm also having unexplained dropouts. Guess it's time to take a look. Been installed now for better than ten years.

Intermittent problems are a real bitch. For some reason tonight, it happened frequently. Yesterday I took a long drive and never had a problem. That being said, I hope all is well now.

But the timing light trick showed me exactly what was cutting out.

I did some studying up on the Hot-Spark. Their site has great info and several test point voltages that need to be in range. About 10000 miles ago I needed a new voltage regulator. Little did I know that 13.7 volts is the limit for this module. The new regulator and Alt put out up to 14.2 at times, with the lights off. So I believe that is what has happened. the extra voltage caused a slow death.

The new coil and ballast resistor should fix that and give this one the maximum life.

Update:
Napa has a 5 ohm BR. Using it i am under 13.7 volts at 4000 rpm. But still about 14v at idle, 950 rpm. So i am leaving it for now. And keeping a spare hs module in the trunk.

Sometimes intermittent ignition problems will also show up as the tach suddenly going crazy when the engine hiccups. If that happens, it is a solid indication that your points or spark trigger is doing something weird.

--DD

Hot spark = Crap

There have been more folks stung by them then I can think of.

I had two fail years ago in two months. Points Rock! Cheap and quick to replace.

Every time I get close to ditching my points one of these threads come up.

I would say that the dual fuel pump relay lost connection for a moment. Common 1.8 problem

This problem has been fixed for a full year now. Doc, did you see the timing light video? Post #6. Would the fuel pump cause the ignition to cut out on each plug wire?

I replaced the hot spark module. I bought a spare at the same time. Then got word that it is problematic.

So if this happens again, I have a spare. Then I will either go back to carrying a spare points and condenser, or maybe bite the bullet and get one of those high dollar distributors or a petronix module.

Either way I believe the problem was the hot spark. when it works it works great. But it does not like the higher voltage and the heat.

Thanks