[alfa] tuning/driving meter - was AD V9 1191

[dmasters@xxxxxxxxxx]

Peter Webb and Eric Storhok are discussing EFI Oxygen Sensors in Digest
1192...

Guys, this is great, you have convinced me again that you know what you are
talking about.
(Again, it makes the donations worthwhile.)

Can you answer a few questions about the tuning of my stock Alfa75 Twin
Spark? These motors must be very similar to the Spiders with their variable
intake cam.
1.  For years I have been running a DVM across some wires connected to the
O2 sensor, and I like to make sure that the reading oscillates around 0.5V
all the time at cruise.  I have adjusted the control on the AFM to see what
difference it makes.  I count the turns.  For a Motronic 4.1 system, is
this a valid way to set mixture?
2.  Will Tech Edge or Megasquirt help me here, or is my real issue that I
need a real exhaust gas analyser to ensure a good mixture.  The few times I
have had the car to a Dyno for checking, the mixture has not needed to be
adjusted, but I do wonder about it from time to time.  There is so little
to adjust, it seems to be more a matter of keeping everything clean and
replacing failed sensors.

BTW, the recommended Spark Plug for a TS is a NGK BCP6ET (different from
the rest of the discussion), however I have found the new Bosch 4 Electrode
plugs to be great.  They seem less prone to fouling than GL, which I find
are best cleaned with a wire brush every 40k kms.

Cheers,
david
---
David Masters
1989 ALFA75 TS grey/grey - daily driver, heading to Eastern Creek Raceway
for "tracktime" in a fortnight.
2000 Alfa 156 TS black/tan - wife's car, she can have it.
Newcastle Australia
----------------------------------------------------------------------------
Date: Wed, 17 Mar 2004 12:21:41 -0600
From: "Peter Webb" <webb.p@domain.elided>
Subject: RE: [alfa] Re: alfa-digest V9 #1191

> The above is a completely different question than the one I
> answered.  What Clay
> was asking for was what to do with his new exhaust system using a
standard
> computer to run the car and make emissions.  For that, I suggested using
a
> heated NB sensor, since that is what the computer uses...  Since
> one is not
> tuning, and the computer can only read a basic O2 sensor, there is no
real
> benefit to a WB for this.  And one can even make an argument that
> a WB might
> not even be as good considering where the computer even uses the
> O2 sensor (the
> synthetic switch from a WB is not as accurate as the real switch
> in a NB- our
> research and control system bears that out).
>
> On the other hand, if you are tuning, WB is the only way to go.
> It is all I use
> here at work.  And the units I have range from $2500-$5000
> depending on who
> made them.  Of course, for any use beyond making perfect
> emission, one does not
> need that kind of tools.
>
> If you buy any of the real WB systems, they would speed up the
> time to calibrate
> your SPICA system like you can not imagine.  And you will also
> find out how
> consistent the SPCIA pump really is- as I found out a few years ago...
>
> I would say go for it- I've got one that I bought from
> Austrailia, and it works
> well.
> or email "unsubscribe alfa" to majordomo@domain.elided

If Eric doesn't mind, to expand on this a little bit, and the source of the
debate last week...

NB02 is exactly what it's name implies.   The stoich voltages .485 to .515
is the entire span of the accurate AFR readings on a NB02.  We talked
around
this last week but never got into details.

Voltages below that indicate lean and above that indicate rich but not a
true represntation of AFR in degrees.  That's the point I was trying to
make.   The oscilation is telling the stock ECU whether you're rich, lean
or
stoich, basically a 3-position switch.   Stock ECU's expect this kind of
behavior, as Eric pointed out.  Now in an off-list discussion, I don't mean
to step on the toes of anyone who does ths professionally.  I don't think I
made the point I was trying to make.   I'm not talking about modern engine
controls here.   That's a far more complex subject with ignition, ion
sensing and the like.

The value of a WB02 is to obtain the true AFR number (lambda in EFI
geek-speak).   The controller will display the true AFR and still output a
0-1v reading for input to the ECU.  What I was getting at in that
discussion
was the best of both worlds when you've modified your car and still use a
stock ECU.   The stock ECU, and we're talking in terms of a fuel-only L-Jet
here, can still use the output from the WB02 controller while the tuner can
get a true AFR reading.

The inherant difficulty with WB02 is calibration.   Each controller needs
to
be calibrated to a specific sensor.  The most popular sensors are usually
covered, being the L1H1 (Honda) and the LSU4 (Bosch).   Both cheap(ish)
sensors.  There are some low-budget and kit based controllers out there
from
Tech Edge and the DIY-WB, that derived from the original EFI332 project,
the
predecessor to the MegaSquirt.   Bruce Bowling is about to release a
precision wideband controller in kit form that works with these low-buck
sensors.   He hasn't given a price point yet, but indicated it's under $100
for the controller itself.  This will be part of the upcoming
UltraMegaSquirt project that brings the MegaSquirt into the 21st century as
far as engine controls go.

Now, I wouldn't buy say a new VW or Honda and rip out the factory engine
control.   As Eric pointed out to me, there's far more to it than just
injector opening times and head temperatures.   If you had a more primitive
system like an L-Jet or early Motronic, EEC-IV, GM-ECM, it would be
worthwhile.   The UMS will support sequential injection.   The debate over
sequential rolls on whether it really buys you much.   I'll try and post
info on these projects as they are announced and released by B&G.  The PWC
(precision wideband controller) might be of interest to many here.
Apparently, the LSU4 sensors are available cheap from VW (~$50).  The L1H1
sensors are a bit more expensive, as anything Honda does.   I hear of
people
grabbing them out of junkyards for short money though.

- -Peter
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