garrett376

A PIWIS2 (possible also a PIWIS1) can recode the instrument cluster to turn off the PSM "logic".

powdrhound

It can not..

garrett376

Just to clarify: you are saying if you unplug the PSM multi-pin plug at the PSM/ABS pump, and with a PIWIS under Instrument Cluster coding for PSM and designate "Not Installed" as the coding, you will still get a PSM warning on the instrument cluster?

powdrhound

Correct. We played with this a couple of years back. Same goes for trying to program the cluster for different fuel tanks, flat bottom GT2/3 vs hump TT. Can't do it. We even had a guy that has jail broken a lot of these clusters and he couldn't crack the codes either. In the end I just got a GT2 cluster but for the most part it's a moot point as I use a Motec display for all data so the cluster really doesn't serve any purpose in my case.

DaveCarrera4

+1 for powder's unplug recommendation. I simply turn PSM off at the track, that works pretty good, but I'm still an 8/10ths driver.

jumper5836

Carlo is correct.
The old Fronts have little grip compared to the new rears causing PSM to intervene.
Had this happen to me as well when just replacing rears and not the fronts with my C4S. So it has nothing to do with the extra power the Turbo has.

For me, PSM stopped intervening when I hit the PSM off button. It was only kicking in during cornering where the front starts sliding. PSM remains off unless your on the brake pedal, which in this case PSM off button did it's job and stopped kicking in during corning, which allowed it to slide a bit during the corner and for me to throttle steer though it.

Jferrante

Thanks as always - my cluster lights up like a christmas tree anyway due to airbag warnings etc. I will be going to a Motec or something similar in the near future as well.

powdrhound

I would never ever replace just two tires on a car to be used at the track. Always all 4. It's just not worth it. It doesn't matter if the car is AWD or RWD, handling will be adversely affected.

TheKane

Quick question for all: why would you go through the trouble to disconnect the PSM system vs just turning it off from the button on the dash? I've never had PSM kick in, even while drifting on wet roads or extensive drifting on snow. Thanks in advance.

mfanatic325

I have experienced PSM intervention during spirited drives and/or random potholes or undulations on public roads; however, I'm also curious as to why simply turning PSM off isn't the go-to solution.

Is unplugging the connector actually a better option?

"02996ttx50

probably because disabling with the dash button has to be repeated continually every time after you tap the brakes if you want psm "off". eg it doesn't "stay" off.

jumper5836

OP posted he had replaced just the rears.

Yes I now replace all 4 due to learning that lesson but at the time I was able to turn PSM off to prevent the PSM kicking in. PSM is very intrusiveness and harsh to the point I thought it was going to cause me to go off, where with it off the handling was easily manageable.

jumper5836

With PSM off, PSM activates during braking, so it is never completely off like how some people want it.

Mike Roblin

I will be purchasing a set of front tires this week to see if that rectifies the issue and I will disconnect the PSM connector as per the advice of this panel of experts and several others I have spoken with. I will just need to be careful in areas of Sebring with little run off or big walls...

I had questioned as to whether or not I could get away with just installing two rears to go with the half worn fronts and it seems to be that my intuition was correct even though I didn't initially follow it.

Thanks everyone for the input, much appreciated.

996tnz

^^^ Same. Forgot to kill it one day and PSM's zombie-mode forced understeer ploughing her on mindlessly rather than let me rotate her in properly at the end of the main straight remains my scariest track moment. Scarier than a couple of spins in my first race/track outings, scarier than losing my brakes at 70 odd mph entering a hairpin, and scarier than having a front wheel break off when I was riding shotgun (those last two in a Honda).

As for easily manageable handling, yes - for our Turbos at least - their PSM unplugged handling is far more consistent and predictable, and it is also faster at ten tenths in almost any situation.

The only time I think we might have been faster or safer with PSM on was a steeply winding uphill section on a tarmac rally where the surface was a patchwork quilt (or think giraffe's skin) of dry patches and standing water (well, actually the water was a bunch of braided streams running across the otherwise dry corners as rainfall much further up the hill had made the roadside drains overflow). In that situation (only one mile of the 40,000 miles I've driven her) I thought we might have been faster with PSM, since the same Nissan GTR we'd been slowly leaving behind under every other condition - from pouring deluge to dry road - caught and stuck with us on that one section. With very different and rapidly swapping grip at all four corners, maybe the PSM computer with it's individual wheel management ability might have been able to do a better on that one. Or maybe not, as I don't believe the 996's PSM holds a candle to Nissan's GTR voodoo.

I would just add though that if anyone inexperienced is going to unplug PSM and push beyond about 8 tenths, whether accidentally or on purpose, it would pay to have practiced car control and skid recovery at lower speeds first, eg at a skidpan or autocross.