MAC11 update

[Rick Houck]

I agree that the grounding is now suspect, although I did take some time to 
scrape the mounting surfaces of the cable terminals. The mounting surfaces 
on my intake manifold and engine mount were blasted clean before assembly 
and installation of the new motor, but I did not check or remove the other 
ends. I will double check those and the positive wires to see if one of them 
has been cut or abraded enough to test good with a meter, but not carry 
sufficient current. It will probably be a few days now, before I will have 
time, so stay tuned.

I do have some dumb questions though about using a scope in an automotive 
application. Should I start with the inputs at the ECU connector, and the 
output at the coil? Also, do the scopes pretty much have two leads (for 
ground and signal), or will we use a trigger lead? Thanks.

Rick

---- Original Message ----- 
From: "Ben Swann" <benswann at verizon.net>
To: "'John Cody Forbes'" <cody at 5000tq.com>; <quattro at audifans.com>; "'Rick 
Houck'" <rhouck at neo.rr.com>
Cc: "'Ben Swann'" <benswann at verizon.net>
Sent: Wednesday, September 10, 2008 3:34 PM
Subject: RE: MAC11 update


> Second that remark - signaling to the coil might be correct, but that 
> amplifier does
> require a good ground as does the coil.  I invariably put them all into 
> one common point
> that tie together in a standoff post on firewall with at least #6 wire 
> running back to
> the battery post - even if the car is a giant ground strap itself.
>
> You will also want to examine the positive feed to ECU - I noted some of 
> the "stock"
> wiring to be seemingly marginal to support a load of a coil, yet seems all 
> goes through
> the ECU - with possible exception of the coil positive feed itself  - I 
> forget how that
> is, but may be something to check.   However, typical coil feed breakdown 
> would occur at
> more like 7000 RPM, not at 2K I'd think.
>
> Still I believe it to be something else than ignition.  I swore up and 
> down I had
> ignition problem on my Megasquirted UrQ with MAC-14 ignition and pretty 
> much went
> through the same things as Rick.  It really turned out to be EFI pulse 
> width was too
> high - injector duty cycle longer than the engine rev.  In addition I had 
> and still have
> a serious fuel delivery problem that is not easy to diagnose or resolve.
>
> On the fuel delivery issue, I believe - an educated belief with lots of 
> trial and error
> - that the tank and pump are not designed to support the type of fuel flow 
> and pressure
> an EFI system requires.  Basically with the lower pressure of the EFI 
> Rail, the fuel is
> pulled into the pump faster than the tank can deliver ultimtely resulting 
> in cavitation.
> Originally the problem reared its head at around 5-6k, but once thing get 
> warmed up, the
> car will sometimes barely get out of its way - sucking - starving - 
> bucking.  Changing
> pumps and lines have helped to a degree, but it seems I either need to 
> find a pump that
> delivers a lower flow, a surge tank setup, or get a completely different 
> tank with
> submersible pump.  If Rick has not experienced this yet with his setup, I 
> suspect he
> will as the 4000Q tank/pump are nearly identical to the UrQ.  And it feels 
> like a
> ignition problem, but not!
>
> Ben
>
> -----Original Message-----
> From: John Cody Forbes [mailto:cody at 5000tq.com]
> Sent: Wednesday, September 10, 2008 3:14 PM
> To: Ben Swann; quattro at audifans.com; Rick Houck
> Subject: Re: MAC11 update
>
> 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.
>
>
>