height sensor voltage output test - Actsus

[sldwys]

Hey guys - So ....I have a ase664 height controller - Lowered the car which was great -

I wanted it to go slightly lower so i lowered out the front Vertical height sensors and lowered out the rear vertical height sensors ( adjustment rods on the read sensor on the front ) like it says in the manual for Actsus.

So After doing this I started up the car and went on our road trip - The suspension even with the height controller on at its lowest setting is about an inch higher than what it was before i altered the sensors. But it is about a 2x stiffer ride.

Have I dont somthing wrong? Is there a lowest reading the ACTSUS ecu can take and with the height controller also faking its reading to be lower is it countering and going back up?

Or have a messed up as when i adjusted the right rear height rod I had to take the rod out to loosen the locking nuts? - Maybe I turned the sensor arm a full rotation accidently before putting the arm back on would this make a problem?? Is there a way to find out what each rear sensor's voltage output is?

thanks.

[Q45tech]

Because of the location where the sensor arm attaches to the lower suspension arm you must measure then calculate the ratio.For examaple if the attachment point is EXACTLY midways then 1:4

3" of tire/wheel range would move sensor arm 0.75"so 1/4" of arm change would be 1" of body height change.

Just like a TPS sensor the ACTUS ride height sensor has a specific reference voltage and reduces that to represent body height.

The FSM describes how to set and reset ride height.

[sldwys]

Ok - Is there a maximum drop that the actsus can go down to? Im guessing I should really start by changing the sensors back to what they were before and kind of go from there -

Also - Would having air in one shock messup the rebound on that one shock? Eg. I accidently took off the accumulator on the front left shock and lost the fluid - And im sure I somehow managed to draw air into the system. Can I bleed this without the Nissan Consult? As the FSM says to use the consult, also can i adjust and reset the height without the consult??

Thanks q45tech - I wish i wasnt so far away from you! ha!

Also im sorry But I cant seem to find which model car (as your different to here in NZ, Mine would of been under fgdy33 Cima) has the ACTSUS FSM to reset and test height Is there a possibility you could please give me the correct link? thanks again.
Modified by sldwys at 4:59 PM 5/3/2009

[sldwys]

pretty please

[3Q Jay]

you should have a bleeder like a brake caliper bleeder at each actuator. on the (H)G50, they are easy to get to at the top of the 'strut' tower. same principle, but you don't have to have an assistant pump the pedal

[Q45tech]

If the Nitrogen pressure in each accumulator [attached to shocks] and tank valves is LOWER than ~~ 900 psi the ride will be hard and jarring regardless of height.

The compressed Nitrogen is the shock absorber for a narrow range [+-0.5"] of motion vs hydo fluid pressure for the +- 3" range.

[sldwys]

you should have a bleeder like a brake caliper bleeder at each actuator. on the (H)G50, they are easy to get to at the top of the 'strut' tower. same principle, but you don't have to have an assistant pump the pedal

Ok, I can see the bleeder, How would I go about bleeding this?? Jack the car up attach a peice of hose the the nipple, Undo the nipple and slowly lower the car until air stops coming out? Should I do this like brakes and Do each corner starting with furtherest away from the fluid filler tank? Also - Is there another fluid I can use instead of the Nissan ACTSUS fluid? As here it costs over 120 NZD per litre. Which is about 60USD per liltre.

If the Nitrogen pressure in each accumulator [attached to shocks] and tank valves is LOWER than ~~ 900 psi the ride will be hard and jarring regardless of height.

The compressed Nitrogen is the shock absorber for a narrow range [+-0.5"] of motion vs hydo fluid pressure for the +- 3" range.

This seems like the problem , It is extremely bouncy almost like it has "cut" springs. Would bleeding this sort it out? Thanks heaps.

also can someone tell me if I turned the rear height adjuster a full revolution on the sensor then set it, is this going to put the difference between the two rear sensors off?

thanks.

[sldwys]

So

If the Nitrogen pressure in each accumulator [attached to shocks] and tank valves is LOWER than ~~ 900 psi the ride will be hard and jarring regardless of height.

The compressed Nitrogen is the shock absorber for a narrow range [+-0.5"] of motion vs hydo fluid pressure for the +- 3" range.

After a bit of reading on how this all works, There is a nitrogen gas in each accumulator on each 4 shocks, If this nitrogen gas drains out (eg, My accumulator on the front left was removed and put back on) oil will fill its place. How do I go about "recharging" the nitrogen pressure in these accumulators? Aswell as bleeding the shocks?? Seriously... I cant seem to find the guide to tell me how to bleed without the consult,

I have read that you can just jack it up and bleed it like brakes but instead of someone pumping you can just jack up, put on hose and slowly lower until no more air comes out, BUT if my accumulators have no pressure in them if this worth doing?? thanks.

[maxnix]

Don't think so, but I am not knowledgeable at all.

Why don't you email Keith Bowers? Texas Oil.

http://www.q45asuspension.com
Modified by maxnix at 1:24 PM 5/7/2009

[sldwys]

Well I thought q45 tech was quite knowledgable so ill wait for some more answers

[texasoil]

The actsus computer tries to maintain the voltage from the height sensors at a set value. THe N/H switch adds a bias to that input when in H setting which 'fools' the computer into sensing the car is too low--so it adds fluid to shocks to raise (height) and voltage to the setpoint target.

All the system senses is voltage from the height sensors + the N/H switch in determining how much oil to add/subtract from a shock. Lowering the suspension will eventually bring the mechanical travel stops into play. Until you reach those mechanical limits, the ride characteristics should remain nearly constant. However, too much pre-charge pressure in the wheel accumulators WILL cause a very firm ride in th eN position as the system pressure needed to maintain the height may be LOWER than th pre-charge pressure in the accumulators, rendering the accumulator ineffective for small bumps. The pressure mentioned by QTech is not correct. I do not disclose the correct value. I sell modified and recharged accumulators.

[sldwys]

awesome thanks texas oil - Do the accumulators Self charge by any chance?

Also If I had removed the left rear height sensor - Rotated it a full turn on accident and then reinstalled to the same length rod as the rear right would the rear left have a total different reading or once the sensor goes past 0 it resets itself? As different sides of the car have different heights at the moment!