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Piggybacking An Auto

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zoomzoom Mentor

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Im going to be installing an adaptronic 440 in my s1 stagea soon. One aspect which Ive been thinking about is controlling a few functions of the auto, ie, sending the ECU a modified TPS signal, and also controlling the line pressure solenoid.

Does anybody have any literature on how the pressure solenoid functions? When the duty cycle applied to the solenoid is higher, it bleeds off more pressure?

To err on the side of caution, I would like to ensure the line pressure is at least slightly higher than stock at lower rpms to cope with the increase in torque. Also, if the standard ECU is receiving a modified TPS signal, it may also reduce line pressure based on that variable.

Has anybody seen or made measurements about when and how much line pressure is reduced?

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scotty nm35 Grand Master

scotty nm35

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Not for the re4, but I have worked extensively on the re5. Sounds like you need to get your hands on the RE4 workshop manual.

Have you seen the programmable PCS auto controllers? Will crap all over what you plan to do with the Adaptronic.

zoomzoom Mentor

zoomzoom

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Indeed it would, but to be honest I am not really willing to spend too much more time and money on this vehicle. The auto behaviour has some annoying aspects, but it isn't the end of the world. Im hoping a slightly skewed (to a lower voltage) TPS signal at low throttle openings will allow me to use some more throttle without kickdown as well as keep the torque converter clutch locked up. My biggest concern is the ECU reducing line pressure in those situations.

I might even be able to make a rudimentary timing retard feature (on gear changes) with the assistance of a programmable microcontroller.

  • 2 weeks later...
zoomzoom Mentor

zoomzoom

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Should be no need to make a timing retard feature as the stock ecu should carry out its normal functions if the adaptronic is in fact piggybacked on.

Maybe Im getting my terms mixed up. The 440 will be controlling fuel and timing, so it won't incorporate the timing retard feature from the stock ECU.

Which brings me to something interesting. Ive been looking through consult logs of the stock ECU, and it seems the timing retard feature only occurs under heavy acceleration. I found periods of around 100-200ms where the timing was reduced to between -1 and 3 degrees at gear change points.

However under regular partial throttle driving I couldn't find any similar timing cuts at gear changes.

For a while I was quite worried about losing the gearchange timing feature. It will be interesting to see if the evidence in the logs mean that losing the timing retardation is inconsequential for regular day to day driving.

zoomzoom Mentor

zoomzoom

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Why would it matter? I have been driving with no timing retard on gearchange for 5 years, and I am still surprised how nice it drives.

I spent a bit of time reading SAU threads on people running auto skylines with PFC or other units which lose the timing retard feature. Judging by the responses, you'd think it was like running liquid glass in your transmission.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

On stock boxes? You would want a shift kit at least.

If the PFC puts the auto in limp mode, different story. The line pressure will spike and the box will shift hard. You need to keep it happy of course.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Just quickly looking into it, the pfc isn't designed for auto cars, so it's like putting a PS2000 standalone in there.

You need to keep the stock ecu in place and intercept the engine sensors while replacing the outputs and keeping everything happy (no codes). If you have issues with this you would be best trying to find a decent tuner with an electronics background to help. I could give you the name of two in Melbourne...

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