MAC11 update

[Rick Houck]

Huw,

You are probably right about the large ground strap on the motor mount, but 
there is still the one that connects to the top rear of the intake manifold. 
I will be taking a closer look at that one.

Rick
----- Original Message ----- 
From: "Huw Powell" <one at humanspeakers.com>
To: "John Cody Forbes" <cody at 5000tq.com>
Cc: "Ben Swann" <benswann at verizon.net>; <quattro at audifans.com>; "Rick Houck" 
<rhouck at neo.rr.com>
Sent: Wednesday, September 10, 2008 10:42 PM
Subject: Re: MAC11 update


> While that's a great point, the main ground strap has to support the 
> starter current, so it's probably ok.
>
> Is there an intake manifold type ground like on the cars I'm used to that 
> goes straight to the ECU, though?
>
> John Cody Forbes wrote:
>> DING DING DING Ben just found a possibility that I haven't seen suggseted 
>> nor checked yet. Check the engine's ground strap for cleanliness and 
>> tightness. Then check it again. Maybe, just maybe, the ground is not good 
>> enough to allow the ammount of current flow required at higer-than-idle 
>> RPM's.
>>
>> -Cody
>>
>> Ben Swann wrote:
>>> Cody,
>>>
>>> That is a good clarification - what this also means is that in order
>>> for the primary signal to be generated, both flywheel sensors need to
>>> be present and signaling and they must sync. up with the Hall sensor
>>> in the distributor cap.  This also triggers the fuel pump.  From then
>>> on out, the primary goes through the Darlington Transistor/signal
>>> amplifier mounted on the coil then through the coil, cap and rotor
>>> and out through the wires and plugs to ground.  So the only things
>>> that could be breaking down are coil, cap, wires or ground.
>>>
>>> Once again, unlike the earlier cars that used only hall signal to
>>> generate primary( five window hall distributor), there is no ignition
>>> timing adjustment - distributor must be in a set position, which is
>>> preferably dead middle of the hall window.  The ECU does the rest of
>>> the timing.
>>>
>>> One possibility that breaks this above "rule" down is that the timing
>>> belt has slack and/or window is just on edge so that the ignition
>>> slips out of window.  Usually this reveals itself in a no-start
>>> condition that is temperature related.
>>>
>>> So - you might have a breakdown in the spark output side, but I think
>>> you have covered thost bases well.
>>>
>>> Ben
>>>
>>> -----Original Message-----
>>> From: John Cody Forbes [mailto:cody at 5000tq.com]
>>> Sent: Wednesday, September 10, 2008 1:08 PM
>>> To: Ben Swann; 'Rick Houck'; 'Louis-Alain Richard'
>>> Cc: quattro at audifans.com; 'P Cole'; 'Ado Sigal'
>>> Subject: Re: RE ; MAC11 update
>>>
>>> What Ben means to say is that all is well with primary ignition
>>> (signal output to the coil), but the ECU knows nothing about whats
>>> going on in the secondary ignition (everything between the coil and
>>> plugs inclusively) and won't store codes for these areas. Thats where
>>> the scope comes in. Get ahold of that scope, your problem will be
>>> diagnosed for sure.
>>>
>>> -Cody
>>>
>>>
>>> Ben Swann wrote:
>>>> Again - what do the MAC-11 codes say.  If 4 4 4 4 then all is well
>>>> with ignition.
>>
>>
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>
> -- 
> Huw Powell
>
> http://www.humanspeakers.com/
>
> http://www.humanthoughts.org/