[T3] Mystery Miss

[William J]

 Could always fuse the test lamp lead just in case . I wasn't talking about 
removing wire 15 from the coil just using the test lamp across the circuit 
so if power is lost even for a second  the bulb should flicker enough to see 
it. I can't say if running a test light between two 12 volt hot connections 
would work since the dome light would stay live the coil would need to go 
ground , that may then find the ground through the condensor and points the 
condensor is charged which may then cause loss of spark and the same miss. 
Even the test lamp bulb filament can act as a fuse. The main idea was to see 
if there is a power loss at the coil #15. I thought of a small 12 volt 
buzzer this would require hearing the thing buzz until it lost power.

 I'm pretty sure Dan has already checked the plugs more than once . And 
changed them a few times . What he describes sounds to me like a loss of 
voltage ign to coil if not and the test light  never goes out it rules out 
the ign switch as well as the power relay for the FI which are fed off the 
same circuit from the fuse box.and all wires in between then I would look at 
the connection between fuse 8 & 9 .

 All Dan needs to do is make sure the lead connected to 15 on the coil to 
the bulb is well insulated where it exits the engine lid or install an 
inline fuse after the wire exits the lid since the power comes from the ign 
switch .

William
----- Original Message ----- 
From: "Dave Hall" <dave at hallvw.clara.co.uk>
To: <type3 at vwtype3.org>
Sent: Saturday, May 07, 2016 5:25 PM
Subject: Re: [T3] Mystery Miss


Be careful with the test light wires - the ignition stays live (and unfused)
whenever the ignition is on.  It's a remote possibility that the miss is due
to an intermittent ignition switch or connection, but it is possible.

I'm not confident you would notice a momentary dimming of the test light on
a normal bulb between 15 and ground. I wonder if a test light, or maybe an
LED, wired between terminal 15 and another live connection - say the
interior light fuse - would remain off until the ignition went off.  That
way you would see a brief flash, rather than try to spot a momentary
dimming.  Obviously you would need to disconnect when not running the car.

If not already done, I think you should check the spark plugs for signs of
one being sootier than the others.  It might narrow down which cylinder is
misfiring.

Dave
UK VW Type 3&4 Club
===================

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Daniel Nohejl
Sent: 07 May 2016 22:44
To: type3 at vwtype3.org
Subject: Re: [T3] Mystery Miss


> On 7 May 2016 at 13:54, Phil Hof wrote:
>
>> One electrical FI gremlin I once had, and is easy to miss (no pun
>> intended) was inside those clear connectors (T1 and T2) that you push
>> a female tab connector into and slide onto the male spade.  One
>> example is wire 19 (pump signal) on the engine bay; another is the
>> head temp sensor connector.  On more than one occasion, I´ve seen
>> them pushed into the plastic housing, but instead of being slid OVER
>> the male tab, they were slid NEXT TO the tab.  It looked fine on the
>> outside if the plastic was yellowed or cloudy, and it would make
>> contact, but as temperature and vibration did their thing, it could
>> lose contact.
>
> Yeah, I've seen that, too. In fact, the first time I saw this it was
> done by a dealer mechanic, so it's not just a novice thing. It's easy
> to do wrong if you're in a hurry, but also easy to do right if you're
> willing to take the extra time to do the job well.

I could see that being an issue but we no longer have any of those T1 or T2
connectors. When communicating with Joe about the harness, there was some
confusion about the "gender" of the FI harness ends vs the main harness
ends. We wound up getting a harness with the opposite gender of what we
needed at wire 19 and at the ECU power wires. While we don't have those
plastic connectors, we have all potentially exposed metal covered with
electrical tape and far away from anything they could contact.

I like William's idea about fashioning a test light for the + side of the
coil. I'm going to get on that tomorrow!
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