Elect Ign Distributor Output LOW?

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6pak

6pak

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Has anyone had a problem with the stock electronic ignition distributor not triggering the ECU?
More than once, I had the situation where the car wouldn’t start, and when I checked it out, I had no fire unless the distributor was spun fast. Spinning slow resulted with no spark.
I pulled the distributor out and with it hooked up, I spun it by hand.
The reluctor gap was correct.
I replaced the reluctor and pickup and everything was good for a while, but then I got bit again.
Connections look good. ECU and coil have all the proper voltages, but it looks like the dist trigger is just not doing the job.
 
What replacement parts are you using? There really aren't any good ones. I hawk ebay for NOS old stuff. @halifaxhops can also help you with quality ignition parts. Beyond that, I would check that all connections are clean and tight, especially grounds.
 
Yes, yes and yes.
Good connections. ECU has a ground strap to it.
Has happened w different ECUs and even a MSD box.
It Maybe the cheap shina replacement pickups.
OR it just may be me. I seem to have all the bad luck.
 
6pak said:
Yes, yes and yes.
Good connections. ECU has a ground strap to it.
Has happened w different ECUs and even a MSD box.
It Maybe the cheap shina replacement pickups.
OR it just may be me. I seem to have all the bad luck.
Click to expand...
Just know you're not alone "THERE". lol
 
I’ve spun the dizzy w a drill and measured AC output.
At 600rpm i get about .7vac
More voltage with more RPM.
Thinking it’s trigger voltage. Yes. Good connections are important with such low voltage.
 
Dist should put out more like 1volt with normal cranking. Might be magnet is weak. There is also a possiblility that it is actually the ECU, but the dist. pickup is obviously cheaper

Also check the connector, for corrosion and 'work" it in/ out several times to scrub the terminals and to "feel" for tightness
 
My money on a ground or ECU problem. The distributor only acts a a trigger like the points did. No power in a trigger. The power is in the ECU.
 
The dist DOES have to provide enough signal. There are no specs anywhere for that level. I have replaced pickups that "magically" worked fine even though there was 'some' signal. It easily could be any of the three, and moreso
 
Appreciate the input.
Im currently not having a problem after swapping out to a spare distributor. But their is something going on.
Just I’ve seen it on 2 of my vehicles.
 
I have seen bad pickup cause hard starting.
Also make sure your distributor is grounded. Probably not much of an issue on electronic ignition but it can be with points. I think this is why the distributor hold down clamps were copper plated.
I always add a ground wire to the housing of the ECU. It must be grounded to the body to work properly.
 
The Chyrs elec ign dist does NOT have to be grounded. A GM HEI dist DOES have to be grounded.

Your voltage readings sound like they are in the ball park. A couple of things to check. When you check the air gap, examine the gap for each reluctor tooth. I have found a variance on cheaper dists. If you find a variance, file down the tight gapped teeth so that you can the gaps equal for each tooth.
I never liked the grouping of the p/up wires with the coil [-] wire. This wire has a ~250 v pulse on it & could cause either no triggering or false triggering. Try separating this wire from the others. Also make sure you have no high tension leads near the p/up wires.
You could also have a voltage supply problem to the ign system. Voltage drop causing low voltage & just not enough voltage to produce a spark.
 
Picup coil. I have some NOS and NORS if needed. Both 6 and 8 cyl.
 
What is the difference between the 6 & 8 cyl p/up coils? Thanks.
 
I have seen a reluctor recently that had different #s when checked on different teeth. Sounded like a Harley. Idle was wacked.
 
8 Cyl are interchangable pick ups the reluctor selects the phasing, the slant the pick up coil is positioned for the six point reluctors phasing if that makes sense.
s-l300.jpg
CR101W.jpg
 
Could be intermittent low voltage. No idea what you are working on. For 70 up models, There is a white plastic connector below the ignition switch that overheats and connection changes with temp and vibration. Electric choke, etc.., can rob voltage too.
 
  1. grab a multimeter
  2. Unplug the Pick-up Sensor (lead from Distributor).
  3. On the Pick-up sensor distributor lead, connect one multimeter lead to one pin in the plug and the other multimeter lead to the other pin in the plug
  4. Verify Distributor Pick-up Sensor resistance is between 350 to 550 Ohms
This is from an invaluable Mopar ignition testing website
Dave's Place - Chrysler Electronic Ignition System Test
 
Like Bewy said; the pick-up coil is just a signal generator, and neither needs nor wants to be grounded.
The P/U is a closed loop system. When the coil is excited by the moving iron reluctor vane, it generates a tiny signal voltage, that just runs around in a circle between the pick-up and the ECU, When the ECU senses it, she then fires the ignition-coil in the usual way. The pick-up does not need nor want a ground.
The electrons are created and pulsed by the moving reluctor vanes. If that wire becomes grounded, spark goes away. If the reluctor stops moving, the sparking stops. If the reluctor becomes magnetized or a vane is too far away, the signal voltage becomes weak, and, if it falls too low, the ECU will not receive or read it.
>@pishta gave a resistance reading. I have tested a few good working coils that were operating at as low as 250 ohms, and or .25VAC when spun by hand. The resistance, and thus the output voltage, seems to vary with temperature, but is a minor thing to the ECU.
>I have tested the coil with reluctor-gaps from Zero to .030 and they worked fine anywhere in that range.
> It is my opinion that those coils are extremely robust, and darn near fool-proof
> The weakest link IMO, is the that the wires from the coil to the grommet at the distributor body have to flex during the operation of the Vacuum Advance canister. Since my first Electronic-Ignition Mopar back in the 70's, I have only ever lost 2 pick-ups both due to one of those wires failing.
>I have seen at least two or three pickups, and they are coded by the wire colors, and are directional as to which way the reluctor spins. If you swap colors you can set the idle-timing and it will run; BUT the engine will not take rpm very well, and a timing light will strobe in random and unusual ways.
>The Small block P/U has one Orange wire. The P-up from a lean burn has a gray wire. And the other one I have seen had IIRC a violet wire.

I honestly think you are looking in the wrong place, as there is NO JUICE coming from the ECU into that pick-up; she is a stand-alone signal generator, and the ECU is not particularly interested in anything about that signal, other than it rises above a threshold level for her to see.
The thing I find odd is that when you replace the pick-up, something changes enough that for a time, she runs normally again, even tho the ECU was not tampered with. Since it has happened more than once, that's a poser.
BTW
1) for testing purposes I have plugged in any ECU from any of my
other Mopars, and it worked fine
2) the dual-ballast is two different-spec ballasts on one platform; one side reduces the running voltage to the ECU, and the otherside reduces the running voltage to the Ignition coil. Don't mix them up. Your engine will run fine when the ballast is cold. Less fine as the ballast heats up. Do not run a 5-pin ECU on full-time charging voltage.
EDIT: see post 20. Just cuz I haven't seen that, doesn't mean it can't happen, lol. Moisture intrusion is a problem for all electrics, so OP, keep your eyes open for it.
 
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I've had trouble with at least two engines where the dist pickup connector was loose/ corroded and had intermittent or no contact
 
With my dist in a vice and spinning with a drill @about 600rpm, I have measured the AC voltage.
I have taken some of the high density earth magnets and stuck them to the metal behind the original black magnet and almost doubled the output. .7 to 1.5v
The magnets have to lay on the correct side or they will actually subtract from the output.
That’s as far as I have gotten, as my engine has suffered catastrophic damage from a dropped valve from a re-man head w less than 100 miles on a fresh rebuild engine.

This will be a new post (don’t want to hi-jack this one) (let’s keep it about distributors) - I don’t want to flame the company until they get back to me and let me know how hard they are going to screw me.
 
A pickup should output about 6V or more at 600 RPM. Cranking engine, distributor rotates at about 100 RPM, with output 1V or more.

Something like a turn to turn short in pickup coil, or fractured magnet could result in significant loss of signal. A turn to turn short may not be measured with Ohm test. It would show up in an inductance measurement, inductance significantly less.

Pickup to reluctor gap also influences signal output, it follows inverse square relationship. A normal gap is bout 0.008", if doubled to 0.016" resulting output 1/4, at 0.032" ... 1/16. Serious attenuation with gap increase.

About grounding distributor body, it helps protect pickup and sensing circuit from high tension spark discharge. Opportunities exist, due to leaving out rotor, dropped plug wire...
 
^^Dave it just occurred to me that a high resistance/ impedance leak in the wiring or pickup to ground, as well, because the pickup circuit in the box is not an "isolated" circuit. "Just one more thing"
 
Meter accuracy could be playing into this as well. Voltages under a volt can be inaccurate depending on your meter quality & health.
 
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