LX570 AHC system pressure?

[Ali FJ80]

I eventually hooked up my LX570 to techstream and was planning on testing the pressure of the system since I threw on a front bumper a while back. I assumed I would be able to find instructions or guidelines on the what the correct pressure etc was online as I had done with out LX470. After much searching and reaching out to @PADDO who is the AHC guru on the 100 series I am fruitless. He was able to provide me with a pdf of the full system and how it works but there was nothing as far as pressure ranges of what is normal or not and he also did not know.

If anyone has any insight or can track down the info it would be very much appreciated and probably good to get this info available on here for future reference so folks can test their AHC to make sure it functioning properly.

Here is screen pic of what the interface for the AHC looks like. Unlike the LX470 which would show you a static front and rear pressure after you lowered and raised it the LX570 starts at 0 and changes as you raise/lower the car but then goes back to zero.

This was while it was cycling back up to neutral from low.

 

[txtortoise]

We need a GoFund account to get PADDO a LX570.

 

[DeckerT4R]

I too would love to see this info!

 

[todiy]

I eventually hooked up my LX570 to techstream and was planning on testing the pressure of the system since I threw on a front bumper a while back. I assumed I would be able to find instructions or guidelines on the what the correct pressure etc was online as I had done with out LX470. After much searching and reaching out to @PADDO who is the AHC guru on the 100 series I am fruitless. He was able to provide me with a pdf of the full system and how it works but there was nothing as far as pressure ranges of what is normal or not and he also did not know.

If anyone has any insight or can track down the info it would be very much appreciated and probably good to get this info available on here for future reference so folks can test their AHC to make sure it functioning properly.

Here is screen pic of what the interface for the AHC looks like. Unlike the LX470 which would show you a static front and rear pressure after you lowered and raised it the LX570 starts at 0 and changes as you raise/lower the car but then goes back to zero.

This was while it was cycling back up to neutral from low.

Were you ever able to find out this information? I am going through troubleshooting my 2011 LX570 suspension and would love to know this information. @PADDO could you please help?

 

[tincan45]

Normal pressure is 8 MPa (1160 psi) and will reach 13MPa (1885 psi) from Normal to High.
High Pressure Errors will trigger if you reach 18.5MPa for more than .3 seconds....That's 2683psi!
Low Pressure will trigger at .6MPa (87psi) if longer than .6 seconds

 

[Ali FJ80]

Were you ever able to find out this information? I am going through troubleshooting my 2011 LX570 suspension and would love to know this information. @PADDO could you please help?

You need a techstream cable to access the data. All over amazon/eBay.

 

[todiy]

This is what I found in the FSM.

Thanks for the help

 

[todiy]

I ran the pressure test and here are the numbers.

	Standard	My Reading
Lo to Normal	8 MPa	12.23 MPa
Normal to Hi	13 MPa	12.14 MPa

The "Lo to Normal" Pressure is too high. In my case there is almost no difference in pressure in both "Lo to Normal" and "Normal to Hi". What does this point to, sagging springs or bad accumulators or something else?

 

[tincan45]

I ran the pressure test and here are the numbers.

	Standard	My Reading
Lo to Normal	8 MPa	12.23 MPa
Normal to Hi	13 MPa	12.14 MPa

The "Lo to Normal" Pressure is too high. In my case there is almost no difference in pressure in both "Lo to Normal" and "Normal to Hi". What does this point to, sagging springs or bad accumulators or something else?

Could be either in my mind, but if the accumulator is going bad, it would makes sense that the pressure goes high and then levels off. Image a worn out spring. It's not going to have much push back in the beginning. I've seen homemade test equipment for the old Citroen globes. Would be interesting to setup a pressure tester for these globes as well.

 

[todiy]

Is this pressure for the height control accumulator only?

I was also thinking that there has to be a little more scientific way of testing these globes than measuring the graduations between Hi/Lo. This could be a good pump for this DIY tester. Other than this pump all I need is a correct coupler/adapter to attach the globe with this pump and it could provide some good information.

 

[highfructose]

I ran the pressure test and here are the numbers.

	Standard	My Reading
Lo to Normal	8 MPa	12.23 MPa
Normal to Hi	13 MPa	12.14 MPa

The "Lo to Normal" Pressure is too high. In my case there is almost no difference in pressure in both "Lo to Normal" and "Normal to Hi". What does this point to, sagging springs or bad accumulators or something else?

Would anyone happen to have a brief breakdown on how to get a techstream to pressure test the ahc?

 

[highfructose]

Would anyone happen to have a brief breakdown on how to get a techstream to pressure test the ahc?

Partial Instructions to test ahc pressure follow
Running techstream

• Turn laptop on
• Start your car
• Double click on virtual box
• Double click on techstream option
• Windows xp then opens
• Double click on techstream icon
• Plug techstream cable into car
• Plug usb end of techstream into computer
• Click Connect to vehicle on techstream
• If unable to connect to vehicle, unplug usb from computer, plug back in
• Click connect to vehicle
• Confirm your vehicle specifics for program when it prompts

Ahc instructions

• Double click on ahc in yellow center box

The next part I’m not really clear in at this time…I’m thinking, based on info in this thread, that one would need to need to

Click on yellow button on left that says “data list” and then cycle the ahc while watching the “oil pressure” related cell in the list.

While watching the oil pressure/mpa related cell, cycle from low to neutral. Then neutral to high

According to this thread,
“Normal pressure is 8 MPa (1160 psi) and will reach 13MPa (1885 psi) from Normal to High.
High Pressure Errors will trigger if you reach 18.5MPa for more than .3 seconds....That's 2683psi!
Low Pressure will trigger at .6MPa (87psi) if longer than .6 seconds”

 

[TeCKis300]

Partial Instructions to test ahc pressure follow
Running techstream

• Turn laptop on
• Start your car
• Double click on virtual box
• Double click on techstream option
• Windows xp then opens
• Double click on techstream icon
• Plug techstream cable into car
• Plug usb end of techstream into computer
• Click Connect to vehicle on techstream
• If unable to connect to vehicle, unplug usb from computer, plug back in
• Click connect to vehicle
• Confirm your vehicle specifics for program when it prompts

Ahc instructions

• Double click on ahc in yellow center box

The next part I’m not really clear in at this time…I’m thinking, based on info in this thread, that one would need to need to

Click on yellow button on left that says “data list” and then cycle the ahc while watching the “oil pressure” related cell in the list.

While watching the oil pressure/mpa related cell, cycle from low to neutral. Then neutral to high

According to this thread,
“Normal pressure is 8 MPa (1160 psi) and will reach 13MPa (1885 psi) from Normal to High.
High Pressure Errors will trigger if you reach 18.5MPa for more than .3 seconds....That's 2683psi!
Low Pressure will trigger at .6MPa (87psi) if longer than .6 seconds”

Good stuff. The way I understand it is that the LX570 AHC pressure sensor only has visibility to system pressure during transition between the height modes. Once the transition completes, a valve closes ahead of the sensor so it no longer has visibility. This is different from the LX470 system where the pressure sensor is in the active part of the system all the time.

That said, pressure is not a useful parameter to understand globe health or failure. That's more a function of volume. A worn accumulator needs more volume to reach an increased system pressure. When I refreshed my globes, the most noticible change was that transitions were quicker, i.e. the system needed less fluid volume to reach the higher pressure state.

 

[highfructose]

Good stuff. The way I understand it is that the LX570 AHC pressure sensor only has visibility to system pressure during transition between the height modes. Once the transition completes, a valve closes ahead of the sensor so it no longer has visibility. This is different from the LX470 system where the pressure sensor is in the active part of the system all the time.

That said, pressure is not a useful parameter to understand globe health or failure. That's more a function of volume. A worn accumulator needs more volume to reach an increased system pressure. When I refreshed my globes, the most noticible change was that transitions were quicker, i.e. the system needed less fluid volume to reach the higher pressure state.

Good info regarding accumulators.

I’ve got new accumulators (relatively cheap at $600 for a set of 4 oem from Japan), though I’m curious how much my default pressures have increased w the addition of bumpers, sliders, tools, winch, etc…and what impact rubbershox spring rubbers will have on that increase in pressure.

Hoping that by testing this I can get some useful data on what the addition of rubbershox (or perhaps spring spacers) can have on overal pressures.

My understanding is that damping may be affected by pressure-thus we should expect a reduction of damping in high mode via neutral. I could be wrong on that though.

 

[highfructose]

the above method for measuring pressures worked.

I ended up with a max of 13 mpa going from neutral to high (12.31 from low to neutral)…which appears to be in spec.

The system gives perhaps 3 readings over the course of the cycle…rather than a constant reading.

I still suspect that bumpers, sliders, etc have strained my ahc system…but other than feeling the vehicle rock back and forth while going over bumps more than it used to, I’m not sure how to diagnose/measure how much augmenting for the load needs to be done.

Having an idea of precisely how much pressure the system is under while under augmented load vs how much pressure the system is under oem load would be ideal…then one could add coils, spacers, rubbershox, etc until the pressure came down within oem range.

I don’t know how to test the ahc pressure in a real time way however.

 

[TeCKis300]

the above method for measuring pressures worked.

I ended up with a max of 13 mpa going from neutral to high (12.31 from low to neutral)…which appears to be in spec.

The system gives perhaps 3 readings over the course of the cycle…rather than a constant reading.

I still suspect that bumpers, sliders, etc have strained my ahc system…but other than feeling the vehicle rock back and forth while going over bumps more than it used to, I’m not sure how to diagnose/measure how much augmenting for the load needs to be done.

Having an idea of precisely how much pressure the system is under while under augmented load vs how much pressure the system is under oem load would be ideal…then one could add coils, spacers, rubbershox, etc until the pressure came down within oem range.

I don’t know how to test the ahc pressure in a real time way however.

What shock mode are you running? While AVS system will adjust, it does defer to programmed damping positions, some of which may no longer be as suitable for your weight level. It's also that more of the mass is located at the extents which will change the vehicles pitch tendencies. Increasing spring rate may minimize that to a degree, but you'll also want to stay in higher damping modes to better control ride motions.

 

[lx200inAR]

the above method for measuring pressures worked.

I ended up with a max of 13 mpa going from neutral to high (12.31 from low to neutral)…which appears to be in spec.

The system gives perhaps 3 readings over the course of the cycle…rather than a constant reading.

I still suspect that bumpers, sliders, etc have strained my ahc system…but other than feeling the vehicle rock back and forth while going over bumps more than it used to, I’m not sure how to diagnose/measure how much augmenting for the load needs to be done.

Having an idea of precisely how much pressure the system is under while under augmented load vs how much pressure the system is under oem load would be ideal…then one could add coils, spacers, rubbershox, etc until the pressure came down within oem range.

I don’t know how to test the ahc pressure in a real time way however.

The AHC module refreshes pretty slow in Techstream. That is why it isn’t “real time”. So here’s a kicker for trying to use Techstream
to measure pressure. The slow refresh rate doesn’t help, and also in a lift situation, if the computer engages the accumulator then the ecu will also attempt to fill the accumulator after the lift process. So you have to also hope you get a pressure reading before the accumulator starts filling. This is probably why you saw the L to N register 12ish MPA.. You should be hitting around 8mpa in that scenario.

I’ve spent a little time considering how to
Measure the pressure as well, but ultimately I agree with @TeCKis300 that it probably doesn’t matter that much. I believe Toyota has a SST that is essentially pressure gauges that attach to the bleeder(a). Even if there wasn’t an SST.. that’s probably the best way to get real time pressure readings.

 

[highfructose]

What shock mode are you running? While AVS system will adjust, it does defer to programmed damping positions, some of which may no longer be as suitable for your weight level. It's also that more of the mass is located at the extents which will change the vehicles pitch tendencies. Increasing spring rate may minimize that to a degree, but you'll also want to stay in higher damping modes to better control ride motions.

Usually comfort mode around 30 mph or less. Middle mode up to 45-50, sport after that.

The spring rubbers definitely reduce the forward to backward movement…as one would expect…I was hoping I could use the techstream to get real time pressure readings and “tune” the suspension w various spring rubbers.

As it is, I’ll have to tune it by feel I suppose.

 

[TeCKis300]

Usually comfort mode around 30 mph or less. Middle mode up to 45-50, sport after that.

The spring rubbers definitely reduce the forward to backward movement…as one would expect…I was hoping I could use the techstream to get real time pressure readings and “tune” the suspension w various spring rubbers.

As it is, I’ll have to tune it by feel I suppose.

Using comfort/normal/sport with AHC shocks would be akin to a static shock and turning up the damping to handle armor and increased spring rates. You've increased weight and spring rates, so comfort probably has little utility at this point.

The system is already speed compensating so there's no need to move up the damping position for speed.

If it helps, Comfort will defer to running damping wide open, positions 1/2. It'll actively ramp up damping for conditions but will tend to run the shocks wide open in straight ahead. Normal will operate aroun 2-4, again using the full spectrum of damping as necessary. Sport uses 8-10. I would recommend running no lower than Normal mode as part of your suspension tuning.

When I'm towing with heavy payload (~8k lbs on tow vehicle axles) and airing up bags, I do the same. Comfort applies too little damping and allows too much body motion. I'll use no lower than normal. Sport for mountain roads.