AHC pressures (1 Viewer)

[katit]

Done. Set of Pleiades ordered. After installing them and new rear springs I expect AHC to work for a while. I did replace fluid yesterday and measured L to H difference around 6-7 marks

 

[katit]

PS: WHen talking about sensors -- They are among the weak parts of the AHC, both because of possible ingress of water/salt and because they wear out, so it's good to have a spare one. The Dorman replacement is not expensive (it's mentioned in a thread in here).

I am keeping my hopes high. Truck is clean, minimal rust. All bleeders came out easily even though one rubber was missing.
Sensors look clean, no corrosion or deposits.

 

[katit]

Replaced springs and globes. Rear pressure dropped by 0.3 Not much but better. I wonder why they didn't come to norm though. I installed "stronger" LC springs

 

[nothappening]

Replaced springs and globes. Rear pressure dropped by 0.3 Not much but better. I wonder why they didn't come to norm though. I installed "stronger" LC springs

I don't think Toyota AHC springs are different from Lexus AHC springs. 6.4 MPa is within spec. Rear pressures are 5.6-6.7 spec. Do you have anything beyond stock in the rear weighing you down?

edit: there's a discussion here, specifically around post #28: Coil springs for AHC

It looks like they're not identical in construction, but very similar in performance/feel.

 

[nukegoat]

Throw coil spacers in the rear. You will retain the spring rate and increase the preload, reducing AHC pressure

 

[katit]

I don't think Toyota AHC springs are different from Lexus AHC springs. 6.4 MPa is within spec. Rear pressures are 5.6-6.7 spec. Do you have anything beyond stock in the rear weighing you down?

I like feel, they work great. No extra weight other than hitch, totally stock truck. Was hoping for more pressure reduction, front is at minimum

 

[trdcorolla]

Throw coil spacers in the rear. You will retain the spring rate and increase the preload, reducing AHC pressure

This, pairing the 30mm spacers and new ahc coils is probably the best you can do for the health of your system with no extra weight.

 

[willyroo]

Old thread, however I want to confirm my best course of action. AHC is currently in good shape, fluid ok, 12 gradations H->N->L, and about to organise a flush, then globes replacement in 10,000ks or so. Rear springs are King Springs KTRS-79, we occasionally tow a camper trailer with ~200kg ball weight.

My front pressures are too low, and my rear pressures are low.

Q1 - The best way to sort out front pressures is via torsion bar indexing?
Q2 - Is 4.8 Mpa for the rears ok (considering the heavier-duty springs)?

Advice appreciated!

 

[thetoyotaman]

You are correct from my experience. Adjust the torsion bars to set front pressure. I wouldn’t worry about the rear since the pressure will go up and probably be in spec with loading and the trailer. Better to not be over pressure.

 

[uHu]

.... My front pressures are too low, and my rear pressures are low.

Q1 - The best way to sort out front pressures is via torsion bar indexing?
Q2 - Is 4.8 Mpa for the rears ok (considering the heavier-duty springs)?

Depends. The missing factor here is the vehicle height, front and rear.
And, are these values representative of an average between several tests going from Lo to N?

But, generally the answers would be yes, altho it might not be required to reindex the torsion bars. Might be sufficient to adjust them a bit.

 

[willyroo]

And, are these values representative of an average between several tests going from Lo to N?

Yes they are, front pressures started at 3.0 and ended up at 2.9 after 3rd cycle. I'm going to check the sensors as well - using the FSM in "The ABCs of AHC".

 

[KR7]

Do we need the program to see pressures? Is there a physical tool I can use instead? I don't believe Techstream is available on Windows 11.

 

[uHu]

Do we need the program to see pressures? Is there a physical tool I can use instead? I don't believe Techstream is available on Windows 11.

You can make TS work on Win11. (But the perfect solution is to find a discarded/free laptop with XP or Win7)

You can use a pressure gauge in the bleeder hole. The t0yota LSPV gauge kit fits perfectly. The benefit of this method is that you get real pressures, not a calculated value based on the pump pressure at the moment of closing the level valve. Values found in the FSM.

 

[willyroo]

Techstream is available on Windows 11.

My screenshot above was from a Dell Latitude 8th Gen Core i5 with W11 Pro. This page will help:

How-To: TechStream In 5 Minutes

Getting Techstream up and running can be a bit of a pain. Hopefully this helps someone get started quickly. Step 1: Purchase an OBD-II / Mini-VCI interface. - I have sold out of my cables and supply chains are back in order, so no reason to purchase more. Anything like this will work: Mini-VCI...

forum.ih8mud.com

For W10 and 11, you'll probably need the visual C++ redistributable, choose the X64 version:

https://aka.ms/vs/17/release/vc_redist.x64.exe

 

[suprarx7nut]

Do we need the program to see pressures? Is there a physical tool I can use instead? I don't believe Techstream is available on Windows 11.

Just last week I tried out an OBD2 scanner and app that worked. The scanner is this one: https://amzn.to/3OTieDm

and the app was OBD Fusion. You pay $5 for the app and then you need the Toyota or Lexus add-on for your car ($15). For something like $65 all in you can have access to AHC data. The setup is a little clunky and it's not as nice as having the entire Techstream screen, but all the info is there.