LOGIE Posted July 19, 2014 Share Posted July 19, 2014 (edited) This might all be in my head, but since I went NA-TT ive been running with a uk speedo/clocks. All SEEMS well but the power steering feels different from what it use to on my NA. Could the uk clocks effect the steering via an ecu. I could just putt in my NA clocks in and see if it improves/feels the same but I wont have the rev counter. I also think the active spoiler is effected it still deploys at 60mph but I now think the spoiler retracts earlier (it used to retract when I went slower than 30mph. Is it in my head or is this possible? Cheers Edited July 19, 2014 by LOGIE (see edit history) Quote Link to comment Share on other sites More sharing options...
listy Posted July 19, 2014 Share Posted July 19, 2014 Isn't the TT engine heavier than the NA engine? Could that be enough to make the steering feel a little heavier? Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted July 19, 2014 Share Posted July 19, 2014 (edited) The Power Steering IS speed proportional . . . When you are stationary you should have FULL power assistance (if it's working properly you can normally turn the steering wheel with one finger) When you are going at a reasonable speed you should have NONE (so you have good steering feel) So at those two extremes your power steering should feel exactly the same. (I doubt if the extra weight of your turbos would make it feel much different) HOWEVER . . . the actual speed at which the Power Assistance starts to reduce I expect will be DIFFERENT with your new dashboard, as the speed signals are obviously different. (the fact that your spoiler retracts at a different speed confirms this) Edited July 19, 2014 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
LOGIE Posted July 19, 2014 Author Share Posted July 19, 2014 Hmmm this is kinda what I thought Roger. Speed signals are wrong. The power steering is working fine whilst static but on the move esp on the twisties it feels very different from my NA. It doesnt feel bad it just feels a little heavy at the wrong times. Im guessing the speedo must send a signal to the power steering ecu (if there is one). I'll refit my NA ones with a TT rev counter and see what happens. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted July 19, 2014 Share Posted July 19, 2014 Well on the Mk4 the PAS is controlled by the main engine ECU . . . So if the speed signal the ECU is receiving from the dash is now different, that could be why. If it thinks the car is going faster than it actually is, it will reduce the Power Assistance at a slower speed than before, which is why you may find it heavy at times. I'm presuming this is a Manual car? (because otherwise I figure you would also have Auto gearbox issues as well, ie changing at the wrong speeds) Quote Link to comment Share on other sites More sharing options...
LOGIE Posted July 19, 2014 Author Share Posted July 19, 2014 Its an auto car but gear changes are fine ie quick and smooth. overdrive works fine also. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted July 19, 2014 Share Posted July 19, 2014 Well I've never owned an Auto . . . but I thought if you changed the dash setup you needed to correct the Speed signal to the ECU, or else the Autobox can end up getting confused, and change gear at the wrong speed. (although I know it uses more than one speed sensor for this) The reason I even mentioned about Autos is that I figured that if you corrected the speed signal in the way that people do for the Autobox, it would also fix your PAS problem. (I know that there are electronic upscaler modules that people fit, usually to correct the kph to mph) Quote Link to comment Share on other sites More sharing options...
ScottC Posted July 20, 2014 Share Posted July 20, 2014 If you're still running NA shocks and springs the car will be sitting a lot lower at the front Quote Link to comment Share on other sites More sharing options...
LOGIE Posted July 20, 2014 Author Share Posted July 20, 2014 If you're still running NA shocks and springs the car will be sitting a lot lower at the front No mate ive always ran TT springs in yellow bilsteins even when I was NA Quote Link to comment Share on other sites More sharing options...
ScottC Posted July 20, 2014 Share Posted July 20, 2014 No mate ive always ran TT springs in yellow bilsteins even when I was NA Either way I'm sure the ride height at the front must have changed. I'd get all the geometry checked out first. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted July 21, 2014 Share Posted July 21, 2014 At no point does the MKIV lose all PAS assistance. It always has assistance, at all speeds, with the engine running. There is a pressure control solenoid in the rack that the ecu opens above a certain road speed. I am unsure if it is a simple two state device (open or shut), or if it's PWM controlled and has a curved response. Either way pressure to the rack spool valve is reduced and steering effort increases. But at no time is the spool valve working pressure removed altogether. Anyone who has been towed in a MKIV will tell you that even at 50 MPH the steering is very uncomfortably heavy with no PAS working. There's also a simple pressure switch on the PAS pump outlet that opens an air leak into the plenum. This pneumatic switch ups the idle speed when manoeuvring, to stop engine revs dropping too low and risking a stall, or causing IACV oscillation. As to the original poster I would check the two and one wire connectors to the rack are in place and undamaged, and the wiring to them is good. And as Roger says, there may be interaction between the speed sensors and the PAS that have become disturbed with your changes. There are so many small things that change when you start "mongrelising" a car. Quote Link to comment Share on other sites More sharing options...
LOGIE Posted July 27, 2014 Author Share Posted July 27, 2014 At no point does the MKIV lose all PAS assistance. It always has assistance, at all speeds, with the engine running. There is a pressure control solenoid in the rack that the ecu opens above a certain road speed. I am unsure if it is a simple two state device (open or shut), or if it's PWM controlled and has a curved response. Either way pressure to the rack spool valve is reduced and steering effort increases. But at no time is the spool valve working pressure removed altogether. Anyone who has been towed in a MKIV will tell you that even at 50 MPH the steering is very uncomfortably heavy with no PAS working. There's also a simple pressure switch on the PAS pump outlet that opens an air leak into the plenum. This pneumatic switch ups the idle speed when manoeuvring, to stop engine revs dropping too low and risking a stall, or causing IACV oscillation. As to the original poster I would check the two and one wire connectors to the rack are in place and undamaged, and the wiring to them is good. And as Roger says, there may be interaction between the speed sensors and the PAS that have become disturbed with your changes. There are so many small things that change when you start "mongrelising" a car. Just caught up with this chris. Cheers for the info. I put my j spec clocks/speedo cluster back in today and steering does feel right again. It was never heavy or light it just didn't feel right..this may sound strange and it may have all been in my head but feedback through the wheel feels normal. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted July 28, 2014 Share Posted July 28, 2014 Yes I have wondered about how many states the speed-proportional PAS has . . . My guess would be that it is not continuously variable, but I think I detect THREE different states, and based on the feel of the steering I would guess the changes are at around 5 mph and 40 mph. Bear in mind my system is controlled by my Mk3 PAS controller, but I imagine (as with most things between the Mk3 and Mk4) the design is very similar. Wouldn't it be nice if this kind of technical design info was written up somewhere?! (I guess we gradually suss things out . . like the ACIS changing at 4500 rpm . . . and now I know the Fuel Pump ECU goes to full power at WOT at 3750 rpm!) Quote Link to comment Share on other sites More sharing options...
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