on "euro" injection.....

[brett@netacc.net (Brett Van Sprewenburg)]

>Okay gang, it's winter time, garage projects are well underway,  there isn't
>much seat time, a good time to do some bench racing and
>engineering................
>
>The topic is CIS"euro injection".  I'm going to ramble on a bit about the
>subject, please correct or adjust my thinking as necessary.
>At any rate, this has puzzled me for some time and I'd love to hear some
>thoughts.   AutoXers, I know this is a little OT, but please bear with me,
>there isn't alot of traffic these days.......
>
>Euro Injection- It's a thick lipped 80mm CIS flow cone/fuel dist/control
>pressure(or warm up reg) regulator.

There is no performance gain from the thick rim, it's just a way to easily
tell the difference between the airflow metering units.

>I'm under the impression that it will
>add some power over conventional CIS and CIS lambda.

Perhaps, depending on your current state of tune.  Also depends on where
you measure (at which rpms and loads) this performance.

>This is the way the
>eBay add reads, the way that RPI sells it, and the way that the end users
>seem to feel about it from conversations that I've had.   In a nutshell, it
>drops the O2 sensor/frequency valve from the fueling equation, runs richer,
>and therefore provides more power.  Accurate so far?

No.  Richer does not always equal more power.  Stochiometric or just _slightly_
richer then stoch. can equal more power.  Especially at higher RPMs...which
would be why even the stock system with the full throttle enrichment system
will only start enriching the mixture after a certain RPM is reached.

>
>But-and here's where I get confused- If I want my CIS lamda fueled 2.0 8v
>motor to get a richer mixture, I can dial it in with the 3mm mixture control
>adjustment in the airbox/fuel dist.

Pretty much. Remember, our system is mechanically biased (heavily) on how
the mixture is generated.  There is a direct physical relationship between the
height of the airflow meter (air flow) and how far the fuel plunger 
moves, which
exposes more of the tiny fuel metering slits, which either richens the mixture,
or leans it, depending (obviously) on air flow plate movement.  Air flow plate
movement depends on engine vacuum, which depends on RPM and load. Whew.

Twisting that 3mm screw changes the physical relationship between the plunger
and the air flow plate arm (essentially one moves while the other 
stays still), ergo,
the mixture is adjusted throughout the air flow plate operating 
range.  Note that
in systems able to adjust the mixture via an O2 feedback system will 
still adjust
the mixture back to stoch, it'll just have to adjust it 'farther' to 
dial out your
mechanical bias...UNTIL you trip the WOT switch.  Then the system goes
open-loop and cuts out the O2 sensor and runs a specific enrichment 
'value' over
the top of the mechanical mixture input, which includes the mechanical 3mm
adjustment bias you dialed in at idle (it's called idle mixture 
because it's SET at
idle, geez).  I'm kinda tired about talking about this, but you can't 
fight the physics
here...get over it people.


>So I'm left to wonder, if I unplugged
>the O2 sensor and dialed in more richness, were is the benefit to Euro
>injection over this?

None, poor low-end and mid-range torque? Bad starting?  Gutless highend? :-)
Some of the above?  Your current system is designed to work with the O2
sensor, you should continue to use it.

> I know from experimenting/experience that unplugging
>the sensor will result in higher emissions and lower mpg, as I'm told the
>Euro inj will.

One of the reasons would be that the euro inj. cannot control the mixture
as well (close to stoch) as the inj. using the O2 sensor.  A certain amount of
richness has undoubtably been dialed in the euro inj., as a rich condition
is safer then a lean condition.  That would be why when the O2 sensor goes
bad, or is unplugged, they injection system defaults to a richer then normal
setting to be on the safe side...you don't burn up pistons and valves when
running rich at the high end. :)

>I don't see where the euro inj is any diff than cis lambda
>with the O2 sensor unplugged.  Anyone got any ideas on that?

See above.

>    Doing this
>for CIS lambda will make the full throttle enrichment non functional, which
>is not a good thing in my experience.

You're right on with that.

> Dan Bubb can back me on this.  Is the
>Euro inj air cone shaped such that this full throttle enrichment is not
>necessary, it's already "in there" and accounted for?

Nothing to do really with the cone shape.

>
>
>Going beyond this simple a/f mixture adjustment , I've heard folks say that
>you could also reshim the control pressure reg. in the fuel dist itself(not
>the block mounted cpr or warm up reg), and arrive at a richer(via higher
>system pressure) mixture.

I've heard this also, and it just might be effective as the mixture 
control unit
is designed to work within certain main and control pressures.  If you alter
'artificially' one of these, then you'll be altering the mixture in 
some way.  I've
heard this story also (concerning the shimming) but I'm not too clue'd in
on exactly how to do it.

>What's  this offer that dialing in a richer
>mixture as above  via the 3mm  does not?

Maybe nothing, depending on how the rest of the electro-mechanical system
reacts to the air flow sensor plate 3mm adjusted bias during 
feedback.  Let's say
that everything in the system operates within an acceptable range, and moving
or changing any one of them (control pressure regulator, fuel 
pressures, air flow
sensor plate counter weighting, fuel plunger rod rest position, air 
flow plate arm
to fuel plunger rod bias via 3mm adjustment, air flow plate rest position) will
result in a different mixture throughout the operation range of the engine...or
maybe only under certain RPM's or loads.  Tuning our engines with the stock
systems is not super precise I'm afraid.  That's the reason why simply changing
nothing else but going to an after market fuel control and ignition system can
result in improved performance...the more tightly and precisely you can control
timing and mixture, the more performance you're going to get.

>  I assume you'd have to uplug
>the O2 sensor for this trick to be of any benefit, but again, I must be
>missing something.

I personally do not see unplugging the O2 sensor an overall performance
benefit.

>I have never tried this, no first hand experience.   But
>again, richer is richer, there must be a reason that this doesn't equate to
>"euro" standards as well.   Still with me?

Remember, richer (beyond a tiny bit pas stoch.) will not improve performance
at 90% of your operating range.  During WOT high RPM motoring, you can
go more and get something out of it.

>
>The crux of the issue:  If I want rich, I can get rich with the stock stuff.

Mostly true.

>So if there is truly any benefit to euro injection, it doesn't soley lie in
>it's ability to run rich.  What makes this stuff special?

It's expensive?  ;-)

>It comes highly
>recommended from some, I'm thinking it's supposed performance benefits
>wouldn't be that hard to emulate with any ole CIS fuel dist.

If you replace a highly advanced FI (not that ours is, just go with me on this
example) that has an undiagnosed malfunctioning injector, or bad fuel pressure
regulator, and poor electrical connections to certain sensors, with a 
set of dual
carbs and got more power...does that mean that dual carbs were the hot ticket
for power?  (maybe in some cases it is, but do you get what I'm saying?)

>
> Whaddya think?
>
>
>Andrew Stauffer

I've said too much. :)

==Brett


 \/  '84 Scirocco (ITB racer 2B) | "Hot VW's, take two home. They're small"
\/\/ '88 Scirocco 16v (Show), '92 Passat 16v (Winter+) | - brett@netacc.net