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'97 Plymouth Voyager 3.0L- There's no spark from the distributor for cyls 1 & 4. Replaced plugs, plug wires and distributor cap to validate there no discharge out of the distributor for those two cylinders, which, of course, are signaled from the same location of the crankshaft/flexplate. A bare wire stuck in those sockets don't spark to ground.
Some critter ate the insulation and wire from the crankshaft sensor, (along with a sparkplug wire). O2 sensor wires were eaten a few years ago, too. In the effort to replace the crankshaft sensor, the old one was frozen into the bellhousing & it snapped off nearly flush with the housing. Salt from Michigan winters can be really diabolical! After hours of dentist-like grinding via mirror (destroyed one new anglegrinder, too), and a halfpint of penetrant, the sensor remnant was finally broken loose with a screwdriver and extracted. Never was there any force driving anything inwards, always twisting and pulling out.
The new sensor was installed with a layer of masking tape, measuring about .006". No spark on 1 &4. Somewhere, I read, the gap should ideally be about .035". So after 5 layers of masking tape, .030" and still no spark on 1 & 4.
I stuck my finger into the orifice while a friend rotated the crank and there's no obvious variation on the the ring/holes. Tomorrow, I'll plug in the OBDII tester which will probably not shed any light on the subject. Also will try to view the ring/holes with a borescope, but that also, won't lead any new clues.
I dragged out 3 junky oscilloscopes to try to view the wave pattern, but 2 are going into the scrap heap, and the only functional one couldn't display a stationary display with idle hunting up and down.

Anyone experience anything like this and resolved it?
 

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Welcome to Allpar. Any 'ck eng' light and fault codes? A P0351 (coil primary A) may be expected if this is a cyl 1&4 ignition primary circuit problem.
A look into the crank sensor hole would be a good idea as a place to start while a helper rotated the crank slowly to may sure that no mechanical issues are present with the flexplate reluctor windows. 0900c1528003c4f8.gif
The 3 groups of windows would control spark for 1&4, 3&5 and 2&6 in a 'waste spark' system.
A scan tool that can watch live data may give you some clues that would be difficult to observe otherwise.
An oscilloscope sweep adjustment would be tough with the engine running on 4 cylinders as the engine speed is all over the place. Even if the sweep could be synced, it would be hard to follow and might just tell you what you already know: that the flexplate signal for 1&4 is missing.
I'd start with a visual confirmation of the flexplate holes. Look for any dings, dents, scrapes or warp.
Some flexplate hubs could crack where they bolted to the crankshaft flange, but why would that only affect cyls 1&4? To me that would be unlikely on the 'Possible Causes' list with this issue.
 
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