Steve Wong Chip and Fuel Quality Switch setting

[RG5]

i

My Steve Wong chip arrived yesterday and I installed it today.

It was a simple chip swap - no wires to disconnect or anything else.

car is a 85 Euro car with SSIs and custom 2in,2out muffler.

Steve supplied me with a Euro spec chip custom version for SSi/muffler.

I have a question:

on the back of the DME there is a 8-position fuel quality switch.

On my car this was set too 6, which is:

+6.3% fuel correction


-2.79° ignition correction


Today I set it back to position 4, which is no fuel correction, but still the ignition correction.

I presume my car was set to positio 6 when it was brought to Australia in the early 90s, when BP Ultimate (98RON) was not available.

Now the car is always used with 98 Ron fuel.

Given the car has the SW chip, I'd like some advice as to whether to set the fuel quality switch to zero, or leave it a position 4.

I would like to know what setting other Euro 3.2 Carrera owners are currently using - either with the factory chip or the SW chip.

Cheers

Rg5.

[ben parrish]

Ask Steve. He helped me with my settings when I lived in Colorado; I had to run -3 to keep it from being too rich at 5,000+ foot.
Good luck,
Ben

[Nine9six]

What Ben said...

[Lorenfb]

"On my car this was set too 6, which is:

+6.3% fuel correction


-2.79° ignition correction"

"Today I set it back to position 4, which is no fuel correction, but still the ignition correction." - RGS -

This basically reduces the increased ignition advance in the performance chip
back to stock or less, i.e. the performance chip just increases the ignition advance
as can be seen here ( www.systemsc.com/tests.htm ).

Here's a very applicable & interesting thread to read:

Carrera Rebuild 10.3 Pistons & Cylinders

[88-diamondblue]

I made to the top Lorens ***** list for the chip topic I feel so privileged. The above topic has nothing to do with chips. Loren, maybe you could explain what the relevance is to this thread and BTW it is a very interesting thread.

RG5

Email Steve, his customer service is what every company should strive for. He will guide you on how it should be set, Anybody else advising you on this is like target practice in the dark.

[RG5]

I have had a very thorough email from SW on the subject and and am now content to run the car at position 0.

[drsimonwong]

Hi RG5,
Would you mind sharing your correspondence to/from Steve? I'm in the same boat and am curious as to your conclusion.
Where are you based? Melb, Syd,...?
Simon

[RG5]

send me a personal message to rgaze911@westnet.com.au

and I will hook you up with the info. My car is now running at position 0 with the SW chip, and the results are astounding.
Simply, astounding.

Rg5.

[RG5]

Im based in Perth.

[Lorenfb]

"I have had a very thorough email from SW on the subject and and am now content to run the car at position 0." - RG5 -

Or until it pings because of; poor gas, hot weather, or heavy engine loads!

If a DME ECM has been set to retard the timing using the internal rotary switch
because of a performance chip or prior to its installation to reduce pinging
or NOx (which was it's purpose), then the net effect on the timing and the
potential engine responsiveness is basically ZERO!

Using that switch in its timing retard modes is the same as grounding pin 10 on
the U.S. DME ECMs. Those that disconnect the pin 10 jumper feel an increase
in engine responsiveness which appears to be similar to the resulting ignition advance
the result of a performance chip. Many who disconnect the jumper during a chip
installation attribute the responsiveness change to only the performance chip
timing advance.

Furthermore, the early 3.2 DME ECMs (prior to '88) had a less responsive chip
which results in more noticeable effects with the additional ignition advance.
Responsiveness always occurs (to a point) when the timing is advanced on ANY engine.
As with ANY change in engine parameters, e.g. ignition advance, compression ratio,
engine temp, or engine load, there's always a tradeoff, e.g. pinging and/or NOx,
or the engine's margin of safety without engine mods, e.g. twin plugs, or knock
sensors.

[RG5]

Perfomance chips ASIDE...for a moment...

In the case of my car, it is an ex-UK car and my suspicion is that it was set to postion 6 (ie, 2.7 deg timing retard, +6.3% fuel) due to the fact that here in Australia, around 1995 the best fuel available was 95 RON. The manual says only to use 98RON.

Since around 1999, however, BP Ultimate has been available in Australia which is 98 RON. So, on this fuel, it could be argued that it iis reasonable to return the rotary switch back to the stock position, ie 0. This is the stock position the car was designed for, for that fuel.

Now, given this position, the change to a performance chip like a SW chip is a personal decision based on risk. If all goes well, then the car will run fine with no reliability problems. You have to put some faith in the product and the development hours gone into it.

I can say, when I first installed the SW chip - but still in timing retard / extra fuel mode - the annoying rasp I got from my custom muffler at 3000 rpm in 2nd gear was eliminated, due as SW advises, to more optimal air-fuel ratios to suit the SSI/custom 2-in, 2-out muffler I have. So, even if no net gain in performance was achieved, there has already been some positive benefits.

I will see how the car goes, if I get any problems I might try putting the switch position back to 4.

RG5

[Wavey]

Originally posted by RG5
the results are astounding., Simply, astounding. Rg5.

Welcome to the vast hordes of satisfied Steve Wong customers. Of course we're all "uninformed" but at least we're happy in our ignorance.


The sooner this becomes a non-issue, the better.

[bigrubberjeep]

I'm glad to hear good outcome from another satisfied SW customer.

This is probably the 100th time I hear a positive response directly from the end-user. I think it's time for me to make the move.

Calling Steve on Monday!!!!

[s5uewf]

I have a 1988 Carrera with Motronic and 3.2.
I have my DME unit in my hand and there is no fuel
quality adjustment knob/dial/screw anywhere.

Did Porsche do away with this in 1988?

There is a blanked off plug on the aluminum outer cover.
Opening up the unit, there is some type of pot
type device with a triangular sort of fitting. But there
are no numbers, nothing accessible from the outside

Anyone know why my 1988 DME seems to have
no fuel quality knob?

[Wil Ferch]

I believe...by your desrciption..it does have the switch.

It's a small black plastic looking thing on the back (?) vertical wall of the DME..and the internal shape indeed has a goofy profile....maybe a triangle as I recall for a special tool that is used to rotate the detents inside. A small flat blade scewrdriver works, too, IIRC.

The switch position needs to be mentally "counted" and there is no indicator on the switch position. I believe...as you view the switch from the outside, that full CCW is "0"...but others should confirm this.

- Wil

[s5uewf]

Ahhh - thanks for the clarification, Will.

I'm going to start searching, but does anyone know
what the default setting should be for this switch?
For example, 3rd click from full CCW, etc.?

[Wil Ferch]

This might be of some help... but I would feel better if others closer to this topic chime in too -->

8 position switch on D.M.E.??

- Wil