AHC and VGRS Help (1 Viewer)

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Joined
Aug 28, 2012
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Location
Battle Ground WA
Hello,

I just bought my 1st 100 Series, a 2006 LX470 last week. I am in the process of baseline and cleaning it up. The dealer i bought the car said they just performed the alignment and showed me the service report on it. When i drove the car home the steering wheel was off center to the passenger side and a very slight driver side pull. I hooked it up to tech stream (1st time using it) last night to perform VGRS system calibration and now i have a centered steering wheel when driving straight but have unequal turns left to right (lock to lock). This issue may have been there already and i just now noticed it. I went under the car to look at the tie-rod ends and notice driver side has 5 threads showing and passenger has 2. What i think i need to do now is to mark the rod ends and move the rod ends to equal them (3.5 threads shown both side). Does this make sense or did i mess up doing the VGRS calibration?


AHC check up:

I did the low to high test and got 14 graduations. Sounds like my accumulators are good.

I measured all four corners: front left 19.25", rear left 20", front right 19", rear right 20.5"
This looks like i need to adjust for cross level. I am little confused with the above numbers i took. Should i adjust front right torsion bar to 19.25" then adjust sensors to get the front and rear ride heights to F19.5" and B20.5" and then move on to reading neutral pressure and adjusting them?

I took neutral pressure reading last night and after measuring and got some weird readings.
F 6.7
R2.7 (why so low??)
Accumulator 10.3
Steering angle -24.75 degrees

I was parked in fairly level garage with the wheels straight ahead. I read that if the steering angle is around 30 degrees the front will isolate side to side to control body roll. Is the steering angle messed up and causing my AHC to isolate the front side to side and cause my weird cross level?

I know i wrote a lot and am thankful for any help.

-Joshua
 
VGRS - you didn't mess up at all. Sounds like an alignment shop has tried to re center the steering wheel by TRE adjustment not knowing how VGRS works (or even that the vehicle has it). I would check that your steering stops on the LCAs are equally set though. Get it realigned to fix the pull and have the TREs readjusted too, then redo your VGRS calibration.

AHC - those front heights aren't too bad at all and the pressure is good. 1/4in lean is within tolerances actually but if you want you could take 1/2 turn off (ccw) the higher side and add (cw) 1/2 turn to the lower side. This should bring it in very close to perfectly level without altering your front height or pressure. Now if you want to lift the front height a fraction then you'll just need the smallest upward adjustment on the front sensor which is reporting the lower or negative value - by this I mean if one sensor (at N) is 0 and the other is -.2in then you'd raise the -.2 a fraction and recheck. If one is +.3 and the other is -.3 then you'd raise the -.3 sensor. Follow? If they are both 0 then you can raise one or both a fraction. For a stock weight front end the pressure to height ratio is roughly 2.2MPa per inch, so a 1/2 height increase will add about 1MPa. You do your final pressure adjustment after height adjustments because when you change height the system changes the pressure, but not the other way around. The hydraulics will be driven by the height sensors feedback - raising to a higher N height needs more pressure, or lowering the N height requires less pressure so you set height then adjust your front pressure to that height. Rears obviously have no adjustment other than new coils and/or adding packers to artificially lengthen and compensate for the usually old and set coil.

Rear pressure of 2.7 is spurious unless you've fitted Oshkosh coils - recheck with the temperature sensor disconnected as per the fsm and see what it says.

The 30 degree steering angle side to side hydraulic isolation isn't an issue here, it only comes into play when you're moving and it's actual activation angle is a function of speed and steering angle input. Have a look at your FG (front gate solenoid valve) and RG (rear gate solenoid) in Techstream and they'll be OFF (they are normally open valves at OFF which causes the left and right sides to be connected, when ON the sides are hydraulically isolated to reduce body roll) while you're parked doing these AHC pressure checks, and your Front Step and Rear Step will be 8, which is the damping stepper motors mid setting. Underway you can see FG&RG toggle between OFF and ON as you throw the vehicle around and you'll see the Step values change the front and rear damping as a function of speed, braking, accelerating- that's the Adaptive and Variable part of Adaptive Variable Suspension. HTH.
 
VGRS - you didn't mess up at all. Sounds like an alignment shop has tried to re center the steering wheel by TRE adjustment not knowing how VGRS works (or even that the vehicle has it). I would check that your steering stops on the LCAs are equally set though. Get it realigned to fix the pull and have the TREs readjusted too, then redo your VGRS calibration.

That's good to hear that i didn't mess anything up. I agree that the alignment shop most likely tried re center the wheel by the TRE.

After alignment and VGRS calibration will i need to do zero point calibration to reset the steering angle?

AHC - those front heights aren't too bad at all and the pressure is good. 1/4in lean is within tolerances actually but if you want you could take 1/2 turn off (ccw) the higher side and add (cw) 1/2 turn to the lower side.

Sounds good I will do that. What puzzles me is the fact that the front drivers side is 0.25" higher that front passenger but the opposite for the rear, rear driver is 0.5" lower than rear passenger. I would think it would have the lean on the same side.

This should bring it in very close to perfectly level without altering your front height or pressure. Now if you want to lift the front height a fraction then you'll just need the smallest upward adjustment on the front sensor which is reporting the lower or negative value - by this I mean if one sensor (at N) is 0 and the other is -.2in then you'd raise the -.2 a fraction and recheck. If one is +.3 and the other is -.3 then you'd raise the -.3 sensor. Follow?

Makes sense.

If they are both 0 then you can raise one or both a fraction. For a stock weight front end the pressure to height ratio is roughly 2.2MPa per inch, so a 1/2 height increase will add about 1MPa. You do your final pressure adjustment after height adjustments because when you change height the system changes the pressure, but not the other way around. The hydraulics will be driven by the height sensors feedback - raising to a higher N height needs more pressure, or lowering the N height requires less pressure so you set height then adjust your front pressure to that height. Rears obviously have no adjustment other than new coils and/or adding packers to artificially lengthen and compensate for the usually old and set coil.

Makes sense.

Rear pressure of 2.7 is spurious unless you've fitted Oshkosh coils - recheck with the temperature sensor disconnected as per the fsm and see what it says.

I laughed at your response. I thought it was erroneous data and I was watching TS and before the final value it was reading 6.4 MPa. I have 2004 LC fsm but no AHC manual so I will need to do some research on where the temperature sensor is and what the fsm says. Would you happen to have that?

The 30 degree steering angle side to side hydraulic isolation isn't an issue here, it only comes into play when you're moving and it's actual activation angle is a function of speed and steering angle input. Have a look at your FG (front gate solenoid valve) and RG (rear gate solenoid) in Techstream and they'll be OFF (they are normally open valves at OFF which causes the left and right sides to be connected, when ON the sides are hydraulically isolated to reduce body roll) while you're parked doing these AHC pressure checks, and your Front Step and Rear Step will be 8, which is the damping stepper motors mid setting. Underway you can see FG&RG toggle between OFF and ON as you throw the vehicle around and you'll see the Step values change the front and rear damping as a function of speed, braking, accelerating- that's the Adaptive and Variable part of Adaptive Variable Suspension. HTH.

As you describe it makes sense for them to use the speed sensors and accelerometers to as feedback in tandem with steering angle and steering angle acceleration to isolate to reduce body roll.

I really appreciate your feedback and contributions on this forum. I spent time reading the "Definitive list of AHC..." thread as well as several others you contributed on and you helped a lot of people out. Its been fun educating myself on this system.

This weekend I will have to do your adjustments after i do the AHC fluid flush and report back.

-Joshua
 
@turbotoyz The temp sensor is on the motor/pump assembly and its connector is the 2 wire one closest to the firewall. Have a look at step 6 of the .pdf (it's a verbatim lift of the fsm) and thank you, happy to help where I can.
Seems fluid can be hard to locate nowadays.

IMG_0298.PNG
 

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