Cylinder not firing
 

Hi,

I have an odd problem. No power coming out of one ot the poles (?) on the distributor cap until you have driven at least a mile. I've checked the pin (? Sorry, terminology failing me) on the inside, and it looks the same as the other, and I have measured connectivity from the inside to the outside.

I am inclined to think the rotor and hall effect pick-up may have too big a gap, is that a thing? I replaced the inner parts a few years ago and didn't adjust anything.

Haynes mentions a gap of 0.1" between the rotor and pick-up, but shown on a Chrysler distributor and my Bosch doesn't appear to be the same.

Am I even on the right track here?

If I pry the rotor out, will anything be adjustable, like on the Chrysler distributor?

Thanks

where are you testing for the spark it could most likely be the HT lead and not the cap,

also if the other plugs are fine then the hall sensor is working OK because there's one sensor and 4 outputs on the cap and the misfire disappears after a mile or so,

Some options to try

check the spark plug for that cylinder

Clean the rotor arm centre and end contact with fine wet and dry sandpaper

try a different ignition lead

look to see if the cap has a hairline crack

Hi,

Before a mile, not after.

There might only be one hall sensor but there are four bits of magnetic metal flying past it, and the gap is over ten times what it is meant to be for a Chrysler distributor.

The car has just failed the MOT on rust, so I have plenty of time to take the distributor apart to adjust this. I wil document the progress and results.

Thanks

good point if any are loose that could be it I have fixed loose ones in the past with superglue,

that rebuild will make a good thread, your distributor must be one like this

http://forum.vccn.no/img-dump/2017/10/277.jpg

maybe one of the side skirts of the plate is bent inwards....just a thought

That's the one. And the gap in mine is much bigger than that, the sensor pretty much sitting up against the outer casing.

Time flies, but I finally took my distributor apart yesterday. Contrary to what the Haynes manual says, and my memory was correct, the pick-up/trigger isn't movable.

The pick-up actually has an inner and outer bit (photo below), so I suspect it doesn't matter where exactly the magnets fly through.

So, I'm a bit stumped. Winter has worsened this problem again, driving the first mile on three cylinders.

https://www.morsing.cc/photos/Distributor_pickup.jpg

Having you done the easy thing of just trying another cap and rotor (and HT lead maybe)?

It's all fairly new and looks clean. I did try sanding the cap studs (?) lightly, but it didn't help.

The coil is brand new as well, replaced it because of this problem. The distributor pick-up is reasonably new as well.

Henrik

I've seen this before, although it was very difficult to diagnose and track down. It was also on a 1960s Ford Galaxie so it had a few cylinders to spare and the owner was content with driving on 7 for the first mile!

So basically it turned out to be related to thermal expansion, either the cap, rotor or both were cracked or damaged slightly but invisibly, so proper connections were not being made until the temperature increase closed the gaps.

It might be worth replacing the rotor and cap for the purpose of elimination, as they are very cheap. Or borrow one from a known working car if you can.
I'd also be checking the resistances on the HT leads to see if one is being temperamental.

I've replaced the cap, the rotor I ordered was wrong, might sand the old one a bit. All looks like new though.

The car has now started surging when driving along the motorway or at medium acceleration.

About to give up on this car as a daily driver. I certainly don't want to break down in this weather!

I will try to pull the plug and see what they look like, but I'm pretty sure the spark never even leaves the distributor.

Henrik