Fuel enrichment - was: (RE: Semi O/T: Got a pickup with2.016V,do I need Motronic?)

[marc_scirocco at sympatico.ca (Marc_Scirocco_Québec)]

I have one web pages with schematics for a 16V Fuel Enrichment device. If
someone wants to host it, LMK

There is also a good post from Chris NG, dating back in 1998, included in
the bottom of this post.

Cheers.

Marc
'83 Scirocco
'97 A4

> -----Message d'origine-----
> De : scirocco-l-bounces@scirocco.org
> [mailto:scirocco-l-bounces@scirocco.org]De la part de rfkellner@snet.net
> Envoy? : vendredi 12 mars 2004 13:03
> ? : mr.utility@highstream.net; treed2@wsu.edu; vwdaun@yahoo.com;
> scirocco-l@scirocco.org
> Objet : Re: Fuel enrichment - was: (RE: Semi O/T: Got a pickup with
> 2.016V,do I need Motronic?)
>
>
> Toby, I would like to see a schematic if available.
> In the mean time, here is a site to the simple version.
>
> http://www.geocities.com/MotorCity/Lot/8341/Tech/CIS-E.html
>
> Rick Kellner.
>
> Original Message:
> -----------------
> From: David Utley mr.utility@highstream.net
> Date: Fri, 12 Mar 2004 10:19:47 -0500
> To: treed2@wsu.edu, vwdaun@yahoo.com, scirocco-l@scirocco.org
> Subject: Re: Fuel enrichment - was: (RE: Semi O/T: Got a pickup with
> 2.016V, do I need Motronic?)
>
>
> Although electronics is not my strong suit, I am interested, especially if
> we
> can figure out a way to build it where it would indeed be weather tight,
> and
> perhaps a better, long-lasting design?  Toby, what type of design would be
> mo'
> better than the Autotech one?  I am interested if and when you have the
> chance/inclination to design something...
>
> TIA,
>   David Utley
>
> Quoting "T. Reed" <treed2@wsu.edu>:
>
> > > > > No, stay away from the fuel enrichment modules.  Almost
> > > > > everyone I've ever heard of having one eventually
> > > > removes
> > > > > it because it ends up causing running issues, either
> > > > with
> > > > > the 1.8 or 2.0.
> > >
> > >  Daun, any recommendations
> > > > for an expose' on
> > > > those?  I shall have to look at that more carefully...
> > >
> > > No expose, just an observed thread that pops up on the list
> > > every now and then, and at least three friends off the top
> > > of my head have had issues.
> >
> > I too have had issues with my homebrew TT-style (relay+resistor) module,
> > as well as my brother with his..
> >
> > In both cases, replacing the relay fixed the problem. A dissection
> > revealed that water had gotten inside and corroded the relay terminals,
> > adding a significant amount of resistance.
> >
> > A better solution would be to use a watertight relay, or design a
> > solid-state FET circuit to do the switching (without a relay).
> >
> >
> > On another note..
> >
> > I have an Autotech module (due for installation Real Soon Now)
> and I took
> > it apart to see what's inside. I found an LM311 (voltage comparator)
> > driving a small relay, a rotary switch and a bank of resistors.
> >
> > It appears to be bringing in the tach signal, running it through a
> > half-wave rectifier to produce a dc signal, then comparing that to a
> > reference voltage (corresponding to ~3000 rpm) and when the comparator
> > output turns on, activating a relay to switch one of the resistors
> > (the one selected by the rotary switch) in series with the DPR to change
> > the current. A lower DPR current corresponds to a richer
> mixture, so this
> > makes sense. Oh yeah, and there is also a BJT that prevents that device
> > from activating unless the full throttle switch is closed.
> >
> > I might be able to post pictures and schematics at a later time, but
> > unless you want to build it on a wire-wrap board or etch a PCB, it's
> > probably too "busy" of a circuit to build your own (lots of components).
> >
> >
> > To be honest, I was expecting better (from autotech?! i know, i know..)
> > Granted, you're getting a lot more than the TT module (it's adjustable,
> > it doesn't activate below 3000rpm and cause bogging, it modifies dpr
> > current directly which doesn't suffer from the same problem as tricking
> > the ecu with the coolant temp sensor.. that the enrichment lasts only as
> > long as it takes the o2 to detect and undo it), but the circuit they
> > used is primitive. I thought maybe they would use a current amplifier to
> > do a linear enrichment based on rpm, or something along those lines.
> >
> >
> > Since the module housing has no grommets or seal sealing whatsoever, I
> > suspect that the reports of failure with the autotech module are due to
> > the same thing as the others.. water getting inside the relay.
> >
> > -Toby
> >
>
>
>
> David Utley
> -----------
> Cable Volkswagen
> 405-470-3129
> 1-800-522-6793
>


>From chrisng@usa.net  Fri Oct  9 01:17:32 1998
To:
Subject: Re: Power Module FAQ
Date: Thu, 8 Oct 1998 23:18:23 -0600


Here's what you'll need..

1) a SPDT (single pole, double throw) relay (you can also use a DPDT
((Double Pole Double Throw)) if you can't find a SPDT) .. I purchased mine
at Radio Shack

2) a 1100 Ohm resistor (Ideally a blue colored one.. I used a brown one
though.. the blue ones have better tolorence)

that's all :) ..  The idea of the power module is to hook it up with your
full throttle switch (I will assume that you have an 8V or 16V CIS-E
motor).. when your full throttle switch is activated, the power module
modifies the output current from the coolant temp switch to the ECU..
Tricking the ECU into thinking that the motor is still cold.. the ECU then
enrichens the mixture to the motor... There ARE a few little quirks with
this system, but I'll get to those and how to get around them in a little
bit.. first, here is the hookup of the module..

RELAY
======
A SPDT relay has 5 pins on it.. Here is the layout of a typical SPDT relay
(also known as a bosch relay):



A relay works with a coil. When the one side of the coil gets energized with
a 12volt signal and the other side of the coil is grounded the coil becomes
energized. When the coil becomes energized it creates a electromagnetic
field with pulls the switch from its defaulted or natural resting position
to the switched position which completes the wanted circuit. When the coil
loses 12volts or its ground the coils electromagnetic field will collapse
and the relay switch falls back to its default resting position opening the
circuit that the relay was completing while its coil was energized.
The relay consist of 5 connection points. These connection points are known
as pins. Two of the pins are for the coil (pins 85 and 86). One of the pins
is for a constant connection (pin 30). The default/natrual resting switch
connection is pin 87. Pin 87 is connected to pin 30 when the coil is not
energized. Pin 87A is the pin that pin 30 is switched to when the coil is
energized..

HOOKUP
========
Now, here's the fun part..

1100 Ohm resistor - Hooks up across pins 87 and 87A

Pin 85-  hooks up to your full throttle switch signal line.. on 8V CIS-E it
should be the violet colored lead coming from the full throttle connector..
You can verify this with a voltmeter.. You can just simply tap into this
line..

Pin 86- Connects to a good ground .. or to a switch inside your cabin, then
to ground (more on this in a bit)

Pin 30- There are 2 wires on the coolant temp switch on an 8V CIS-E.. If
memory serves properly, one is blue/yellow and the other is brown.. One of
these wires is energized 12V.. the other wire (I belive it's the brown one)
is your coolant temp signal line.. Again, check with a voltmeter to make
sure you got the right one.. you do NOT want to cut the 12V line..  Cut the
signal in two .. You will want to connect the line coming out from the
coolant temp sensor to pin 30

Pin 87- Connect the other half of the coolant temp signal line, the half
leading back to the ECU to pin 87

Pin 87A- No leads connected.

You're DONE!

CHECKING IF IT WORKED
======================
Full throttle enrichment occurs when 2 criteria are met
a) Full Throttle switch is activated
b) Engine is at over 4000 rpm (8V) or 2500 rpm (16V)

You can sit there with an idling motor manually activating the switch and
nothing will occur.. However, with the power module attached, cold engine
enrichment occurs whenever the full throttle switch it activated.. with the
motor idling, if you activate the switch a few times, you should be able to
detect a change in the motor idling speed.. if the motor's idle changes when
the switch is activated, then the power module is functioning properly..

HOW IT WORKS
=============
When the full throttle switch is activated, a 12V signal is sent and
energizes the coil in the relay.. with the coil energized the circuit
between pin 30 and pin 87A is complete.. since the 1100 ohm resistor shorts
pins 87A and 87, current is modifed by the resistor and goes to the ECU, via
pin 87...Enrichment occurs..

When the coil is not energized, the circuit between pins 87 and 30 is
completed.. current goes to the ECU unmodified.. Enrichment does not occur..

KNOWN PROBLEMS
=================
1) The reason the module works is because VW's tend to run lean at higher
RPM's.. the extra enrichment helps out this situation and provides more
power at these RPM ranges.. .However, because of the design of the module,
it does not detect what RPM you are at.. it enriches the mixture whenever
the full throttle switch is activated.. this leads to situations when the
enrichment actually robs the motor of power.. Imagine cruising at 2500rpm..
then having to accelerate quickly..you get on the accelerator all the way..
then full throttle switch is activated..enrichment occures before you hit
the "lean" part.. power doesn't come on quite as strong as it could because
you are now running an overly rich mixture..
A quick and dirty solution for this situation is to hook up a switch inside
the car to turn the module on or off.. This is done by hooking up a switch
in series to Pin 86.. This way, when you are just cruising around, you can
keep the unit off .. driveablility will not be sacrificed.. When you need
that extra power to pull you thru the weak spots, you can simply flip the
switch to activate the module..eg: When acclerating away from a stop
quickly.. keep module off thru 1st and 2nd gears, in 3rd gear when you hit
4000rpm, activate module..

2) 1100 ohm was used as the resistor value becasue the Techtonics unit used
the value.. Perhaps your vehicle requires a lower or higher value resistance
for best power.. at 1100 ohms the ECU belives the coolant temp is around
30-35 degress C (about 86-100 degrees F)..Cold running enrichment no longer
occurs when coolant temp reaches 50 degrees C (122 F).. (I could be wrong
about this... ) .. at 50 degrees, resistance is about 900 Ohms..  at 0
degrees C (32 F) resistance would be at about 5000 ohms.. the higher the
value of the resistor, the richer your mixture would be.. instead of a fixed
value resistor, you could hook up a variable resistor (Potentiometer) across
pins 87 and 87A and have it in your car as well.. Value should be variable
between 5000 ohms and 900 ohms .. this will allow you to "fine tune" the
ammount of extra enrichment your vehicle requires..

3) You may want to create some sort of case to enclose your module to keep
it away from the rain etc.. I'm not too sure what would happen if it got wet
and started to short ..


REAL WORLD TESTING (aka: Seat of my pants)
====================

86 GTI - 270 Cam, no cat, 2 1/2" exahust, K&N filter

Before Module-
1st Gear- Had never been a problem..always pulled cleanly and realativly
hard to redline
2nd Gear -Pulled strong as well till about 5500 rpm, when it would pull into
redline roughly
3rd Gear - Would hit about 5000 rpm, then started to wheeze it's way to
redline.. 5000+ rpm felt very soft
4th Gear - Same as 3rd.. would pull till about 4500 rpm, then make it's way
up the rest of the way lazyly
5th Gear - Never have tried to max out the car.. so I have no clue :)

After Module-
I can now pull to red very quickley and easily using gears 1-4.. in 3rd and
4th you can feel the little rush come on at about 4000rpm.. don't ask me
about 5th gear though.. still havn't tried to run 5th all the way to
red..not enough road and too many cops :)
the problem with low rpm enrichment is quite evident though.. if I get on
the gas all the way in 3rd runing under 3500rpm, the car does not pick up
quite as quickley as it did without the power module.. I will be hooking up
a switch to my system soon, which will hopefullyl solve this quirk..

CONCLUSION
============

It's only $20.. what do you have to lose?


Hope this helps.. if you need further assistance, don't hesitate to e-mail
me back
Chris..


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