[urq] EFI + MAC-14 maxing ataround 5k RPM

Ben Swann benswann at verizon.net
Wed Oct 24 19:31:58 PDT 2007

So we think it might be ignition after all.  I guess I'm not seeing where the ignition
signal drops out.  I do see the pulse width spike when the RPM drops.  Are you looking
at the log from today?


Cody, is there someway to turn on the ignition pulse graph line in the logfile?


I remain sceptical at this point about the ignition part, even though it was my original
speculation.  The more I have looked at the ignition the more it looks correct and even
an improvement over stock.  Unless I'm getting some parasitic draw on coil primary or
losing current to coil output, but I don't see that.  I do have the coil driving the
tachometer - would that be more of an effect on the MAC-14 than it was on the MAC-02?


How can we see what is happening to the coil primary?  How can you see if spark is dying
at high RPMs?  Anything else to look at?


Also, remember - although the log shows ignition (timing advance, etc.) it is not being
used.  I have been contemplating installing 5 window hall and using MS for ignition as
well.  I just figured AUDI probably does this a little better.





From: QSHIPQ at aol.com [mailto:QSHIPQ at aol.com] 
Sent: Wednesday, October 24, 2007 10:18 PM
To: cody at 5000tq.com; quattro at audifans.com
Cc: benswann at verizon.net
Subject: Re: [urq] EFI + MAC-14 maxing ataround 5k RPM


In a message dated 10/24/2007 7:19:55 P.M. Central Daylight Time, cody at 5000tq.com

>What you refer to is known usually as 'Hybrid Alpha-N' which was pioneered on the F40
IIRC. MS >can be run in speed desnity mode, MAF mode, alpha-n mode and hybrid alpha-n
mode, but most >run speed density with only a very small handfull on either form of
alpha-n. Anyways, yeah Bens >setup is on MAP vs RPM with modifiers like air temp,
coolant temp, TPS accel enrichment (like >a carburettor accel pump).


It appears from below, that this setting is working, but I bet one has to become
familiar with it using a 272 cam on a turbo audi....  



>I just looked at a log file where Ben started the engine and slowly let it run up to
5k. Duty cycle >is perfectly fine, never higher then 50%. From what I'm seeing it looks
like an ignition missfire. >TPS stays perfectly still, but for one split second the
vacuum goes away and simultaneosly the >O2 reads lean, while the MS tried to compensate
for it and bounced the fuel up a bit. Everything >in the settings looks good too, BTW. I
call ignition problem, but I have no suggestions for why :-(.


That makes more sense to me, it sure appears fuel is there.  Ignition:  RPM signal
falling out - weak signal, worn teeth, bad sensor, wiring issue...   Arc: in the wires,
distr, and/or rotor.  Bad plug/s.  Incorrect IAT sender.  



>MAP reprogramming is not something most can do, this is assembler language stuff burned
on >the CPU and frankly should never need to be edited.


Isn't there a software adjustment for load value, or is that adjusted for in the VE
tabling?  There has to be a way to trim the load values without a reburn, since that
will vary as MS is installed on various motors.  Curiousity more than something that
needs to be done, it certainly appears fuel isn't the focus anyhow.  


Scott J



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