Sad to say, I still have not closed out this job with the necessary steps
posted here. Next week, we were due to travel from home in Brisbane on the East coast of Australia to Perth on the West coast of Australia -- similar road distance as New York to Los Angeles. The vehicle is now located in Perth in the hands of my daughter and son-in-law -- who are not yet 'AHC-trained'! Meanwhile the Western Australian State Government (Perth is the State Capital) is holding fast on COVID Border Controls and quarantine arrangements, so we are delayed yet again!! When I finally get there, the review will be methodical as described at the above link. However, so much of the AHC system on this vehicle has new OEM replacement parts – four ‘globes’, AHC Pump, three Height Control Sensors, Height Control Accumulator, two Front Shock Absorbers, but no issues nor replacements of the original Rear Shock Absorbers nor of the original Damping Force Control Actuators nor the ECU nor associated relays and fuses.
So my primary suspicions really are air still in the system, and/or, improperly adjusted Height Control Sensors causing slow ECU response.
If the AHC Pump was not new, I certainly would suspect blocked internal strainers and reduced pump delivery pressure and flow. Maybe I have to check the new Pump anyway!
The vehicle has a few additions – ARB Deluxe Bar, Toyota tow-bar, Kaymar Rear Wheel Holder for additional spare wheel – but it is not particularly heavy. Weighbridge says 2,920 kilograms (6,437 pounds) with 141 litres = 37 US gallons of diesel fuel in tanks, no people on board, no other load – but 1HD-FTE turbodiesel is at least 120 kilograms (265 pounds) heavier than 2UZ-FE. Whatever, the vehicle weight is well within the FSM guidance on AHC weight limits but is much heavier than the stock kerb weight – so there will be some slowing effect on raise times. I don’t think weight is the whole story.
The vehicle also has Firestone Coilrite airbags inside the KING KTRS-79 Rear coil springs. It has been suggested that friction between the airbags and their Kevlar covers and the coil springs also will have slowing effect on raise times – possible – but I don’t think that is the whole story either.
So I think for me it is “back to AHC basics” – I will report further when I finally get that done.
Previous AHC Fluid changes were done twice by my independent mechanic when doing other work. He is a good man but I know he was in a rush at those times and for my own satisfaction I would like to bleed the system myself.
The PADDO Method for bleeding is excellent but when there are ongoing suspected residual air problems, I favour multiple bleed cycles from all five (5) bleeders including movements “N” to “HI” to “N” to “LO” to cause the Height Control Accumulator to discharge and recharge multiple times and to cause the AHC Fluid in the ‘globes’ and in the Shock Absorbers to empty and refill as far as possible multiple times. These never are completely ‘flushed’ because there is no ‘through’ path for the fluid – for example it moves in and out of the Shock Absorbers, not through the Shock Absorbers from one end to the other, and there always is some ‘unswept’ volume at the bottom of the Shock Absorbers. The solenoid valve at the Height Control Accumulator is normally closed, only opens on two occasions: (1) when releasing fluid to raise the vehicle “LO” to “N” or “N” to “HI”, and, (2) when the AHC Pump recharges the Accumulator with fluid after a raise has completed. When nothing comes out of the Accumulator when bleeding, it is because it has not been recharged and there is nothing in there -- assuming no other problems such as faulty solenoid or the system being in one or other of the 'fail safe' modes due to other faults.
I do use the “Active Test” at Page 6 of the attachment – with a paperclip bridging Ts and E1 in DLC1 in the engine bay, easier than using DLC3 under the dash as shown in some FSM versions -- to ensure that the AHC Pump is primed and to push fluid into the system. This helps but by itself will not ‘flush’ the system. The vital thing is raising and lowering the vehicle as part of each bleeding cycle, so as to get as much affected fluid and residual air out of the system as possible, being careful to shut off bleeders during outflow so as not to draw in any air.
This has turned into another rambling post – but maybe it will give you a few thought starters.
