[Healeys] Austin Healey 100 Misfire Diagnosis.

[Alan Seigrist]

Michael -

Just as a follow up to my email since the symptoms seem to manifest
themself  ...

   - whether the car is warmed up or not - this typically will exclude
   anything related to fuel or the coil
   - whether the car is under load or not - this typically will exclude
   anything related to fuel
   - whether the choke is pulled or not - this typically will exclude
   anything related to fuel
   - somewhat intermittent but systematically under all conditions -
   suggests to me wiring / ground issues

Given this I'd check (as a priority):

   - Battery Master (when these fail they will ground the coil)
   - primary ignition wire (white) from the switch to coil (cycle the
   connections)
   - motor ground straps (cycle the connections)
   - loose wires in the dizzy
   - loose ignition wires into the dizzy or spark plug

Other things to possibly do (as secondary):

   - replace rotor
   - replace dizzy cap

I don't think it would be contacts or condensor simply because this would
either be very regular all the time, or maybe sensitive to temp.

Best,

Alan


On Thu, Sep 29, 2022 at 4:46 PM Bob Spidell <bspidell at comcast.net> wrote:

> re: "... I don’t recall if that wire is separate from the distributor wire
> ..."
>
> It is (or should be). If the battery switch is in the 'OFF' position it
> grounds the coil primary so no spark.
>
>
> On 9/28/2022 8:34 PM, Alan Seigrist wrote:
>
> Hi Michael -
>
> Have you tried cycling the connections on the white wire from the ignition
> switch to the coil, and also from the coil to the distributor.
>
> You might also want to try disconnecting the black and white wire at the
> coil from the battery master switch - if it’s failing you’ll get weird
> symptoms like this.  If that wire is disconnected the car should run no
> problem.  I don’t recall if that wire is separate from the distributor
> wire, if it isn’t you’ll have to disconnect it from underneath the master
> switch itself.
>
> Best,
>
> Alan
>
>
>
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