Date:         Sat, 19 Sep 2015 19:14:34 -0700
Reply-To:     Angus Gordon <birdworks@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Angus Gordon <birdworks@GMAIL.COM>
Subject:      Re: Cause of weak spark?
Comments: To: David Beierl <dbeierl@attglobal.net>
Comments: cc: Andrew Martin <ramblinvan@gmail.com>
In-Reply-To:  <201509200106.t8K16pZZ014319@mail46c45.carrierzone.com>
Content-Type: text/plain; charset=us-ascii

Thanks David, but it's not the ECU. I have a spare which I tried.

I'm almost out of troubleshooting time (back to work), but doesn't the ECU control the coil power ground? Why the high voltage?

Angus



> On Sep 19, 2015, at 6:06 PM, David Beierl <dbeierl@attglobal.net> wrote:
> 
> Run over to Andrew's and try a working ECU.  If that's the problem, which I strongly suspect, yours can probably be brought back by cleaning and resoldering the joints in the ignition driver portion.  Looking at the back of the main board, there are heavy traces running down one side.  Those traces, with associated components and the first two transistors on the heat sink, are the drivers for the ignition and the injectors.  The ignition driver works at a high enough voltage (peaks around 400 volts for a few microseconds) that it will arc over solder fractures and eat the solder away from the joint leaving a blackened mess that may need to reconstruct the pads to fix before it finally gives up completely.  See photos 9-16 in https://picasaweb.google.com/117189706757545167023/SolderFatigue?noredirect=1 (all photos in that album are from 2.1l ECU).
> 
> Yrs,
> d
> 
> At 08:12 PM 9/19/2015, Angus Gordon wrote:
>> '86 syncro
>> 
>> I'm looking to solve a weak spark problem. Battery voltage is present at the coil (D15 power currently coming from G2).
>> Coil has been swapped.
>> New dist. cap and coil wire (swapped).
>> Grounds re-cleaned below coil.
>> 
>> Am I correct that the coil ground is through ECU pin 19? Under the coil?
>> My brain is as weak as my spark right now.
>> 
>> Thanks for any help,
>> 
>> Angus
>