mallory broke

Mallory distributor and electronic ignition under the cap.

Suddenly the Bug is running on two cylinders. No spark for two. Everything under the cap looks just fine. Clean as new. So, before I pop for new innards, let me have it - anything known to go futz in these things that a guy can fix himself?

Reply to
John J
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Try over att the shoptalkforums, Raby and the gang use quite a few.

J.

Reply to
P.J.Berg

I had to remove an electronic ign equipped distributor on a '67? Sqbk. It was a dead #3 spot in that electronic ign adapter. I popped in a 009 and the power came back and the owner was able to continue his trip. I showed the owner the no spark before I changed out the distributor. I would think that your electronic ign adapter is also malfunctioning. :-)

I personally like the electronic ign adapter except when they malfunction! lol

Reply to
dave AKA vwdoc1

The distrubutor would be the last place to look. They either fail altogether, or not. It's impossible for the electronic unit to fail only for some cylinders.

First use a timing gun, using the inductive pickup lead in each one of the spark plug wires with the engine running. If it flashes, then there is spark in that cylinder. If not, then there is no spark. If there is no spark, use a different spark plug to see if the old one was defective, check if the HT wire is in contact with some other object (metal or plastic tube, wire etc) that could cause a High Voltage leak to find an alternative path to the ground. Use a new spark plug wire in this case. Check the conectors on the ends of the spark plug wires.

If there is spark to all plugs (detected by the timing gun method) then it's not an ignition related problem.

Do you have dual carbs?

Bill Spiliotopoulos, '67 Bug.

? "John J" ?????? ??? ?????? news:u9SdnfvjTvHpw3bUnZ2dnUVZ snipped-for-privacy@supernews.com...

Reply to
Bill Spiliotopoulos

I am skeptical because I am a computer programmer. I know that firmware can be set to mess up through bad feedback, or just plain bad programming.

Done that. No spark.

How friggin likely is it that two sparkplugs will fail at exactly the same time? Hey, I know QM metrics and the odds are astronomical. If ya know what astronomical means.

It ain't. I'm careful about that. I'll even send you a picture.

TWO and two only.

Reply to
John J

Well that depends....at least on the pertronix, I had one that was very intermittent, turns out it was a broken B+ wire inside the insulation, right at the module. It would cut out, buck and just generally drive me crazy on cold acceleration, once warm, it would run fine. Took me a while to find it because it would never ever act up once it was warm.

Also on the pertronix, the little magnet ring that you press down over the distributor shaft could break as well, leaving one or more cylinders un-triggered. Unlikely, yes...impossible, no.

Had another guy with an old ford pickup running that mallory electronic trigger unit in his distributor. The thing would cut out for no reason at all but it would always start right back up. He chased that problem for months, we looked at the wiring, thought it was the coil, a bad ground, bad ignition switch, and so forth. In the end it was determined that it was the trigger module. Popped a new one in, it's run like a top since....

Never say never.....personally I've seen some really weird failures. My all-time favorite so far was the bug that had an alarm on it. Ran like crap, owner could not figure out why. When I got to it I discovered the relay that some idiot installed into the main B+ to the ignition coil was chattering, and it caused all kinds of weird running troubles. Once I took the relay out of the circuit and restored a solid B+ supply to the coil ALL of the driveability issues went away. That chattering relay was playing havoc with the spark voltage and when the engine would stall, you could hear the idle cutoff solenoid chattering in the carburetor if you listened closely. The failed relay was treating the idle cutoff solenoid as though it were one of those 'feedback mixture control solenoids' the electronically controlled carburetors use.

Chris

Reply to
Hal

This is weird because if this is the same unilite style that I worked on, it has a slotted wheel that rides with the ignition rotor, and the slots allow the LED's to see each other at the proper time, triggering a spark. Logic would seem to dictate that it would either fire all of them or none of them. I don't see how it could fail on just two?

As far as a quick and dirty test, can you put a regular distributor in there and see if that gets all four working again? You could also check for continuity between the terminal under the cap and the terminal where the plug wire attaches for the affected cylinders. Maybe something inside the cap went casters-up and that's why you see no spark at the plug?

Not too likely in my book unless you have bosch platinum plugs in there. I've seen those things drop like flies in my own experiences....

Which two? Two in a row or 90 degrees out? Although I don't know how one failure mode could be more explainable than the other to be honest.....

Chris

Reply to
Hal

Me neither, unless it has some kind of firmware that got confused.

I'm going to do that and probably shitcan the Mallory if the other works.

Reply to
John J

John, is this in the 58?(I think it was a 58, the car you purchased from Micah)... If so, have you checked to see that you haven't had another episode with mashed electrodes on those two cylinders? this would account for no fire at all, even if the Mallory was triggering it to fire...

Reply to
Joey Tribiani

Bill................ Improbable but not impossible! ;-) I have seen it happen that a distributor with the electronic adapter did not fire on only 1 position. I could not understand that one and I even took the adapter out to inspect wiring and distributor lobes and trigger wheel. All looked good but even after I reinstalled it, it still had 1 dead spot even after a new rotor and cap were installed. I think I even put it on my Sun machine/scope, but I don't remember now. lol

Another distributor brought all cylinders back online with the original spark plug wires. :-) I guess I could have reinstalled the original points and condensor but I gave him a nice deal on everything and it was so much easier to show and let him feel the results. ;-)

I agree with using an inductive timing light or other means and test the spark coming out of the distributor.

Reply to
dave AKA vwdoc1

It's just a plain electronic device. No microprocessors, no firmware. If the unit is partially working causing misfires, then it would not be posible for the misfires to be constant at the same cylinders, as it has no way to know wich cylinder is firing. The problem is somewere else.

Bill Spiliotopoulos,

67' Bug.

? "John J" ?????? ??? ?????? news:UY2dnYe3xeCnUHbUnZ2dnUVZ snipped-for-privacy@supernews.com...

Reply to
Bill Spiliotopoulos

There are diodes, transistors and coils in there? I do not know the layout, but it could be related to rise-time or saturation time if you want in the trigger circuit. That could explain why the two same cylinders misfires.

J.

Reply to
P.J.Berg

That would be rpm dependant, and you could never have the same 2 cylinders constantly misfire. For example if you have #1 and #3 misfire, after you switch off the engine, the problem can be transferred to cylinders #2 and #4 with equal possibility. The distributor has no way of telling when it's firing time for #1, it just produces a spark when a slot passes in front of the optical sensor.

If specific cylinders misfire, you have to look for malfunctioning parts dedicated to these cylinders, such as the spark plugs, the wires, higher compression on those cylinders but weak spark, HT leads connections, distributor cap defective.

Regards, Vassilis.

Reply to
Bill Spiliotopoulos

Was it a Mallory Unilite? or with a magnetic ring?

Bill Spiliotopoulos, '67 Bug.

Reply to
Bill Spiliotopoulos

I don't think John specified...

Reply to
Joey Tribiani

Unilite.

I will dive in there again Saturday unless it's raining or snowing (it's outside) and begin all over again. Thanks to all who helped.

Reply to
John J

IIRC The one that I replaced was a modified Bosch distributor with the electronic ign kit on it.

Reply to
dave AKA vwdoc1

That makes sense, modifications for bosch distributors use a ferrous ring and magneticaly detect each firing point, or similar technology. A defect on the ring can cause constant misfiring on one of the cylinders. However on the Unilite this is not possible because the firing points are detected by the interruption of a light beam, from a slotted cylinder under the rotor. Assuming the slotted cylinder is clean and in good condition, the unilite will trigger all four cylinders, or none if the electronic module is damaged. Lack of spark to specific cylinders is because of something else.

Bill Spiliotopoulos, '67 Bug.

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Reply to
Bill Spiliotopoulos

thanks for clearing that up and getting it to make sense! ;-) I have seen these modified distributors work well also!

Reply to
dave AKA vwdoc1

No spark on those plugs, doesn't necessarily mean that there is no High Voltage, just that the plugs don't spark.

I recently had one NGK spark plug go bad, by internal damage which prevented it to spark. But I doubt that this can ever happen to 2 plugs at the same time. Unless they are fouled, or the timing was over advanced or the fuel mixture too lean and the plugs were burned. Did you remove the plugs to inspect them?

Do you know which cylinders are not firing?

Bill Spiliotopoulos, '67 Bug.

Reply to
Bill Spiliotopoulos

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