TeamSwift

How about this:
I mounted a second WTS right next to the original one by means of a hose-clamp. Thermically it gets heated just like the original WTS. Its connector is in series with a resistor (electronic store). Technically the second WTS is connected parallel to the first, but with a resistor in series with only one of the TPS's.
This was originally done to reduce the sootiness of the exhaust, something it also does rather well in addition to saving gas during warm-up.

What it does: During warm-up the engine gets an exceedingly enriched air/fuel mixture. That wastes gas and produces loads of soot.
With this setup, the enrichment during warm-up is reduced. That saves lots of gas and reduces the soot-output. With about 15km to and from work daily, the savings are easily noticable, and sootiness is greatly reduced. Obviously, the colder it is outside the greater the savings.

How does it work: This setup tells the ECM that the engine has warmed up more than it acually has. The over-enrichment is thus reduced. The resistor limits the effect to normal once the engine is warm. (Without the resistor, the temp-guage would show overheat and the ECM may retard ignition when hot) There have been no running or accelleration problems during winter, and it is often below zero in these parts.

Please Note:
The 3-wire WTS and the 1-wire WTS type may have different electrical resistance! No matter whatever sort of WTS you originally have in use, the additional WTS should electrically be of the same type as the original one! If in doubt, compare their resistance at room temperature laying side by side. On the 1-wire, measure between case and the single pin. On the 3-wire, between center pin and case. The case is of course connected to chassis under operational condition. Manufacturing tolerances in WTS-resistance of up to 20% are nothing to worry about. Differences of two to one or even greater indicate electrically different types that should not be used together for this mod.

The other two outer pins of the 3-wire WTS are used for controling at which temp the radiator fan comes on. Leave these pins untouched for this mod, because a not-working fan is a time-bomb for the life of the engine.

KoeGeo's gallery has a fine electric circuit diagram for this mod.

Cheers,
Helmut

If the area you live in is not so cold.... sounds like a good idea. The problem if you live in a area with freezing temps, is the car could actually stall out if not fully warmed.

This is a very good idea, just make sure you car can handle comming off the fuel enrichment circuit early without problems. IE don't pull out in front of other vehicles until your sure if your vehicle can handle it without hesitation or stalling/stumbling.

Another benifit over fuel savings is your catalytic converter should last longer!

Hi vert guy,
This modification has been working fine in my car since last summer. It is now the middle of winter and minus 20°C is not unusual.
Cheers,
Helmut

was thinking about this some more

if you have a way to digitally monitor the coolant sensor temp from the ECU on an ODB car (e.g. with a scangauge), you could wire up a variable resistance potentiometer in the temp sensor wire and mount it (the potentiometer dial) on the dashboard somewhere.

then you could "dial up" whatever engine temperature you want the ECU to "see" at any time, depending on what you want to do...

e.g. for leaning out the mixture as soon as practical after a cold start, or, enriching the mixture for more fuel for passing or merging, or racing ford aspires.

or if you didn't want to use the potentiometer, you could do it with a resistor on a switch . label it "mpg" for on and "power" for off.

do you mean the additional sensor is in the coolant flow too? or is it getting heated outside the motor by physical contact with the original sensor?

The resistor and switch on the WTS wire is an old hodrod trick,but we
would go opposite from where MPG guys want to go,made the engine
think it was cold,more fuel,more spark.Do not see why it would not
work just as the other way too...Think our German friend is just clamping
to the side of existing sensor and it 'sees' the heat through the metal
castings..Great idea!

Yep! The additional WTS is mounted such that it gets heated just like the original WTS. Mounting it on the flange that houses thermostat and WTS is good enough. Just make sure there is a good thermal contact. The series resistor being in series with ONE wts limits the resistance-reduction of the total assembly when hot. This is because of two reasons: 1) the beneficial effect is not needed when hot, since no enrichment "choke" is needed with a hot engine. 2) Because the temp-guage also uses the same WTS it would read "very hot" or "overheat" without that resistor limiting total resistance when at operating temperature.
Btw: The sooty exhaust and sotted-up cat is a thing of the past!
This mod works so well you don't need a switch or a potentiometer.
The improvement has well been worth the effort, and it paid off within a few weeks.
Cheers,
Helmut

the only reason i would be interested in a switched setup would be for the ability to digitally monitor "true" engine temperature once the engine has warmed up.

if that's not needed or desired, then your method is the way to go.

I like your idea. What is the resistance of the WTS (coolant temperature sensor in US) at cold, and at normal operating temp? I'm just interested in seeing or repeating the calculation you used to choose the extra resistor. I'd like to put this set-up on my car too. Thanks.

F C OHMS
210 99 190
160 71 400
100 38 1250
70 21 2350
40 4 4780
20 -7 8100
0 -18 14,650

Info from 96 Metro FSM-----------

Thanks for the resistance-table!
As you may see, the 500 Ohm resistor has no substantial effect over around 130°F / or about 60°C. At that temp you hardly really need any enrichment.
Helmut

Helmut, KoeGeo -- I'm impressed.

I'll get a sensor and resistor and get after it.

i keep coming back to this idea. while i understand what the electrical goal is, i'm still having trouble with the details on how it happens.

can someone explain the electrical theory at play in terms a 5 year old could understand (i.e. me). i'll explain it as i think i understand it.

are my following assumptions correct...

- WTS resistance decreases as the coolant temp increases.

- let's leave the extra 500ohm resistor out of the discussion for a second...

- what i fail to grasp is how the second WTS in parallel results in a net *decrease* in resistance. my mind wants to tell me that the presense of 2 resistors doubles the resistance.

- or does the *parallel* configuration halve the resistance (assuming equal resistance values), whereas 2 resistors in *series* doubles it?

sorry for the basic questions. i never had any electrical theory in school (or i forget taking it).

feel free to use basic analogies to help me out. if talking about it in terms of streams and dams and fish etc. makes it easier, go for it!!

Correct, electricity flowing through a line is like water through a hose. A resistor is like a restrictor plate in that hose. Put 2 in series and the resistance to flow is doubled. Run them in parallel and resistance to flow would be halved.

okay - thanks for clearing that up for me.

In simplified form:
A) When starting the cold engine, it starts just as usual. The fuel/air mixture is just as usual during cold-start.

B) During warmup, the lower resistance tells the little computer (ECM) the engine is warmer than it actually is. Because of this, the over-enrichment of the fuel/air mixture is reduced. That saves fuel and prevents the catalyst from sooting up.

C) The resistor limits the effect to temperatures where the effect is needed. Therefore, this setup has no affect on a warm engine.

Summary: It is a cheap mod. My exhaust is not sooty any more (was awefully sooty) and it saves gas as well. There have been zero negative effects, in particular the car does not stall when cold.

Helmut

Helmut, Is this the way we are to wire your modification?If so it will
be one of my weekend projects...Thanks for the Good Info!!!

any of you electronics gurus able to help me wire this modification using a potentiometer and switch?

i've got the parts, but i want to clarify the best way to wire it.

resistors in parallel have less resistance than the lower resistor in the set. the equation is R = (R1*R2)/(R1+R2)

so a 400 and 500 ohm resistor in parallel have a 222 ohm resistance.
and 190 and 500 ohm resistors give 137 ohm.

The simplest thing to do would be to install a temperature switch on the engine somewhere and wire it so that when the engine is cold it adds a 3-500 ohm resistor in parallel to the WTS so during cold start it shows the engine warmer than it really is and after the engine is actually warm it goes back to normal on its own

I have seen temperature switches like this:
http://cgi.ebay.com/Two-Over-Temperatur ... dZViewItem
but I really haven't put much effort into figuring out if they are suitable for this setup. There are switches made for automotive stuff and can probably be found at the local auto parts stores if you want to hunt around and find a suitable part number. To make it really simple it needs to be a switch that is closed until a set temp of anywhere from 130-160 then it needs to open.

http://www.digikey.com/scripts/DkSearch ... 73&Site=US

that one is the one ideal for this mod. It can handle up to 170C so any engine getting close to that temperature has other problems to deal with. The contacts open at 75C or around 160 F.

I would go ahead and grab a few potentiometers and a resistor assortment while you are ordering stuff from there. It would make it a lot easier when you are experimenting with stuff if you have extra parts, they also have tons of toggle switches.

KeoGoe's diagramm is exactly the right way of doing it!

I would certainly not use a switch- design for mpg. That also has the disadvantage of the engine running terrible while switch on and cold.
Helmut.

Keogeo's diagram seems to have been deleted by admin. Can someone please repost, so I can see position of 2nd sensor and wiring?

yeah, does anyone know what's up with that message? "The Extension 'jpg' was deactivated by an board admin...."

i've seen it all over the board in many threads where there used to be images.

Sorry I didn't add a diagram, but look at the first post of this thread.
I thought it was worded so plainly that no question arrise, sorry.

When you do this mod, don't waist time fiddling with pots and switches! Just do it as suggested in the first post. The series-resistor makes no difference when the engine is cold, its just to limit the effect when it becomes halfway (and beyond) warmed-up. Without the resistor, the engine would not run right when warm and hot, and depending on the exact model, the temp-guage might falsely indicate overheat and the timing get a little retarded. This we don't want.

Once you've tried this mod as layed out in the first post, you'll probably be so happy with it that you don't want to further mess with it. I did mess with it and tried further tweaks, but the original mod as posted on top can not really be improved on. A further benefit is that the cat and EGR-system and combustion chambers remain very much cleaner. That in itself improves economy again.

Cheers,
Helmut

Can anyone get a picture of this?
BTW: KP for you Helmut.