3.6 conversion idle behaviour with Steve Wong chip
 

Hi!

I have a 3.6 Varioram in my -87. It has a light flywheel and only simple cat-only exhaust. The Steve Wong´s chip was ordered for this.

I was wondering is this normal idle behaviour for my this kind of setup:

When cold the idle first stops to ~2000 rpm and the slowly to about 1000rpm
Like this:
YouTube - Porsche 3.6 idle cold

When warm the idle first stops to ~2000 rpm and the slowly to about 850 rpm
Like this:
YouTube - Porsche 3.6 idle

I was always thinking that chip was programmed this way to prevent the stalling problem with the light flywheel? Im I right?

btw. I havent found any vacuum leaks.

neither of mine works like that, is the engine from a tiptronic by any chance?

Yes it is from a tiptronic...
What does this mean?

The tips had a somewhat different idle control scheme than the manual transmission cars. I never got into it but do remember something about a throttle pot.

You'll have to look into it in the service manuals

another difference is the backup light actuation

Thanks for the tips.
I have a couple of long flights coming next week, so I might have time to dig into the manuals...

TIP and manual were different in the DME harness (backup light signal) but the DME is identical. There is a coding jumper close to the 55-pin connector that tells the DME to be for a manual or Tip car.

When selecting TIP the DME uses a different map set, a different idle speed and listens to the shift signal from the Transmission control unit. Every time the transmission shifts the DME will momentarily lower the torque output of the engine by retarding the timing.

Ingo

So can i by-pass the signal with some jumper (wire) or is it in the software?

pics of the dme
http://i216.photobucket.com/albums/c...1082009459.jpg
http://i216.photobucket.com/albums/c...0082009455.jpg

Thanks Ingo, I knew there was more to it but as I said I've avoided tips

The jumper is not inside the DME, it is a plastic plug with a wire loop that plugs into the DME wiring harness. The harness should have one 3-pin and one 2-pin connector branching off close (within a couple of inches) to the 55-pin connector. One is to select the maps (ROW, US) and the other is to select wether the DME is in a manual car or a Tiptronic car.

If the 2-pin plug is installed onto the 2-pin connector it codes for a Tiptronic. Left open codes for a manual transmission.

Ingo

Thanks for the great instructions!!! Now i have to wait for three weeks to get to my car :( , because im skiing in the Swiss alps offcourse!

964 and 993 are slightly different
964
http://forums.pelicanparts.com/uploa...1298904620.jpg

993
http://forums.pelicanparts.com/uploa...1298904658.jpg
http://forums.pelicanparts.com/uploa...1298904692.jpg

Jaskas:
Maybe involve chip originator Steve Wong with any future actions on this ? ......

Not to hijack the thread but I just put a SW chip in my 3.6 conversion and it seems to hunt up and down at cold idle for maybe 15-20 secs before settling down instead of just holding a higher idle. Any ideas on what I should check?

Yes I think i should contact Steve Wong at some point too.

Bill V: Do you think that connecting the terminal 42 off the ground would help me with the idle issue? The 964 engine would have been much easier.

Or should there be a 2 pin connector in the 993 harness too for the tip/manual selection?

With the 993 the "jumper" for Tip vs. Stick went inside the harness. You need to find out which pin needs to be connected to GND inside the harness connector so the DME will switches to Tiptronic mode. In that mode it will interpret the signal on pin 42 for the idle RPM reduction and the torque reduction.

You need to find out how the maps were done on the chip. A stock chip many differnet maps and the DME uses them depending on how it is coded (tip, stick, etc). One strategy is to change all the map sets with the one and only tuned map set. Another strategy is to change all the pointers to the one tuned map set. Both will ensure the tuned maps are used no matter what the jumpering is set to.

Third, only one map set for ignition and fuel is changed. If that is the case, jumpering the DME for a Tip results in loosing all the tuning that was done.

You could use the AC compressor signal to raise idle. As far as I know the idle will be raised when the compressor clutch is activated to compensate for the additional load. This is true for a Tip as as well as for a stick.

Ingo

Now i had the time to dig into this issue.

I found from the manual and instruction how to wire the harness:
http://i216.photobucket.com/albums/c...11/wiring1.jpg

Are these soldering in the root of the harness somehow ralated to this issue:
http://i216.photobucket.com/albums/c...5042011204.jpg

The dme plug:
http://i216.photobucket.com/albums/c...11/wiring4.jpg

So guys...!

The pin no 42 determines the gear selection and the rpm reduction. Does it also affect to the power and torque? Do i want ground or not?

The pin no 44 is for Tip-coding. Should it be ground or what with manual transmission?

Any Ideas?

sub'd

This is really a case where you would need a Hammer or PST-2 to check what the DME is "seeing". From experience all these inputs are active low. That means when nothing is connected the internal pull-up resistor makes them high and thus inactive. So my educated guess is that you don't want to connect anything to pin 44 because you don't have a tiptronic. If you select tiptronic you'll end up using different maps. When you are in stick mode configuration pin 42 is probably not even evaluated.

I would try to pull pin 40 (AC clutch) and/or 41 (over-run shutoff) to GND. This will influence the idle speed and behavior. Try experimenting with these pins and see what the engine does and if it improves idle stability.

Ingo

For the problem with the idle: As the self-learning functions learned them selves enough ( after the battery was disconnected for couple of months ) the idle settles now much better. So i beleive that infact there was no fault in the system. The ECU didn´t just have the time to adapt to the parameters.

For the timing retard issue: If had the workshopmanual with me on a couple of boring flights and now i found out that in the late tiptronics the encrypted coding for time retard is only ON when the sifting or idle. So when the pin 44 doesnt get any signal the timing should be normal.

Great!