Time/risk to adjusting torsion bars

[ylexot]

First thing I am doing us getting pressure measurements for front and rear. That's what I wanted to start with, but difficulties with the software and the poor ride frustrated me to what seemed from multiple witnesses to be safe action. It want this system dialed in and an squared away. If that means new accumulators and/or pump. That's ok. I want my system to work as designed.

What I don't understand is why my system looks so much different than the diagram w associated specs. Is this variation within the limits of the system, or is there a larger reset, like reindexing needed? Or, is this the product of reindexing that wasn't done carefully, or what?

 

[PADDO]

First thing I am doing us getting pressure measurements for front and rear. That's what I wanted to start with, but difficulties with the software and the poor ride frustrated me to what seemed from multiple witnesses to be safe action. It want this system dialed in and an squared away. If that means new accumulators and/or pump. That's ok. I want my system to work as designed.

What I don't understand is why my system looks so much different than the diagram w associated specs. Is this variation within the limits of the system, or is there a larger reset, like reindexing needed? Or, is this the product of reindexing that wasn't done carefully, or what?

Is that snapshot of the torsion bar anchor specs from a conventional LC? I'm not familiar with the complete doc that contains that image so it would be helpful to see the entire doc so we can compare and contrast with known good AHC specific TB adjustment documents. The other time that snapshot image was posted up and the member was adjusting their TBs to it, instead of following the AHC docs that say to adjust TBs for cross level and to a pressure, he ended up a long way from where he wanted to be. I've previously asked for the whole doc containing that image to be posted but nothing was forthcoming so I can't offer an explanation as to why your system looks different.

 

[ylexot]

What kind of OBDII dongle do you have? Can you get an app for it? The type I have uses the Torque app (Android) on my phone and it really was "plug-n-play".

Here is a link to the techstream tool I bought. It has a full size USB on it. Did you use a full to micro USB adapter to connect it to your phone? I saw another ODB2 reader but it connected with bluetooth, but I wasn't sure if it would be able to access the AHC readings. If I can do everything with my phone via a little bluetooth dongle that can live in the cab, I want that!

As for the diagram, I haven't yet found an FSM for the 100 series. I don't know what the full context of that diagram is, but saw it posted a couple times while searching. From what I could gather from the threads, that diagram is relevant to replacing the TBs. I just happened to notice that my bolt was standing out from the framework, which is the opposite it should according to the diagram.

 

[r2m]

The whole thing is bluetooth. No wires or cables except the charging cable for long drives.

 

[ylexot]

That sounds remarkably painless. Can you use the android ap to read AHC pressures and other interesting tidbits from the ECU?

 

[r2m]

I'm not sure since my wife and I both have 98 LC's. But there is a bunch (read dozens and dozens) of options to read like voltage, air temperature, basically anything that has a sensor on it, the Torque app should read.

Anybody with AHC that's used the Torque android app want to chime in???

 

[TriArcher]

Followed

 

[Toyo72]

From what I've read, you need Techstream and a mini-VCI in order to access AHC pressures and make adjustments. I think @r2m is referring to a general OBDII reader which has a wireless connection to an app on a phone to read fault codes and general data like MPG, charging voltage, water temp, etc.

 

[PADDO]

From what I've read, you need Techstream and a mini-VCI in order to access AHC pressures and make adjustments. I think @r2m is referring to a general OBDII reader which has a wireless connection to an app on a phone to read fault codes and general data like MPG, charging voltage, water temp, etc.

Correct on both accounts. To access the AHC ECU you need to use Toyota's interface, TechStream, legitimately available off their TIS website or pirated. Other legit companies like iCarsoft also sell hand held scanners which will access the vehicles ECUs like AHC, body, engine etc in addition to the standard OBDII data bus. I surmise iCarsoft are using TechStream under license. The DLC3 plug in wireless scanners are extremely useful and versatile test and monitoring tools but I have not found a source that sells a wireless tool which will also allow access to ECUs other than what's on the OBDII bus and maybe a bit more. If/when someone comes up with a wireless interface that allows access to the proprietary ECUs like AHC I guess we will be all over it, alas 'till then most of us have to drag out the old Dell, 13 years old in my case and still going strong, sort off.

 

[Ali FJ80]

Having done this adjustment this weekend I was shocked what a difference a few turns of the TB makes to the ride of the LX.
After all the techstream endorsements I ordered the amazon one as I figured I should probably see how the wifes LX is doing considering I had never adjusted anything on it. Both front and rear pressure were barely over the normal range referred to. I turned both torsion bar bolts 4 full turns and now both front and rear are within spec. By the way I did this without lifting the truck, the bolts turned without much issue. Figured the numbers were so close before that it would be a non event as far as ride quality. Took the truck out for a ride and it is dramatically smoother than it was the last time I drove it. I even had MAF 30mm spring spacers as well as set of non-ahc rear spring to play around with if I was not able to get it in spec but I will shelf all of those for now. Best $30 spent in a long time although loading the software and getting it to work was probably the most painful part of the experience and took 10 times longer than the actual work.

 

[ylexot]

Interesting to know that you can turn the TB adjustment bolts without jacking up the front end. That will save some time. @Ali FJ80, I'm glad you got yours to work. Are you running XP, or Win7+? If Win7+ what instructions did you follow to get it to work? My last try was using these (link). Driver seems to work, registry matches, but despite my efforts, it just errors out when I try to 'Connect to Vehicle'.

 

[Ali FJ80]

I also read to lift it first but decided to give it a shot and they turned without much problem. I figured it may depends how much pre-load is already on them and knowing mine had not been touched I gave it a shot. I could feel the resistance getting stronger by the end but I was at a good spot. If it gets very hard to turn probably best to lift and take the load off. The software had me going crazy on my win7 machines also and I eventually gave up and dug out an old laptop from 10 years ago with xp and it worked.

 

[PADDO]

The AHC TB adjustment procedure actually calls for the vehicle to be on flat level ground, not lifted. If you want to take a bit of TB preload off you can always raise it to H for your adjustment, gives extra head room too! Don't forget that AHC vehicles have scrawny little 25.2 mm diameter TBs, not big thick manly 31mm bars (or larger if diesel or after market) and they take more effort to tweak, hence un loading the front end.

 

[Ali FJ80]

Good to know I accidentally did it correctly lol.. So many threads say so many things it gets confusing.
Figured I would get some use out of the rear spacers on my LC since the LX did not need them and I guess it sounds like I will need to lift to adjust the torsion bars of the LC.

 

[ylexot]

OK. So I finally broke down and got an old serviceable notebook computer to run XP and pretty much be a designated garage computer so I can talk to my LX via Techstream. I got it plugged in and working. (Yeah for small victories.)

Height sensors are giving what seem like good readings. I was able to test all the solenoids etc, and things seemed like they were working: relays clicking, random hydraulic noises, leveling adjustments, etc. However, when I read my AHC pressure, it shows 0 MPa across the board. Obviously there is pressure in the system. The AHC is working, just poorly.

A couple weeks ago, I took it to a friend's shop and he plugged it into his official computer. It read the same 0 MPa, but I chalked it up to the bad pin in his reader. It seems that ODB2 isn't reading the AHC pressure.

Tips on trouble shooting?

 

[PADDO]

Are you raising the vehicle from low to neutral before reading the pressures? TechStream reads the pressure transducer output voltage as the leveling valves and the height accumulator valves close, so you should see them sequentially populate and stabilize as the vehicles settles at N (from L). And if you are on level ground and your physical cross level is good I'd look at adjusting that 0.6 inch front sensor closer to 0.0. If you are raising to N before reading and not getting any pressure values I'd suggest putting a voltmeter across the pressure transducers terminals, raising the vehicle and check for an output.

 

[ylexot]

Well that explains a bit. It doesn't read a static pressure but a change in pressure from the last position. I'm sure that's in the notes somewhere, but I missed it.

New wrinkle, I noticed that the AHC was turned off while running tests on the relays and solenoids. (I'm sure I did something ill advised straight from the hammer-and-screwdriver, just apply more force, mechanic's cookbook.) I went through the whole test sequence again and couldn't get the AHC to turn back on, nor did the on/off button on the AHC control make any change. I tried power cycling the car, ignition on/off. No change. I am holding out hope that a test drive will make a difference, but not a very strong hope.

Thoughts? (other than read the damned instructions first...)

 

[PADDO]

It's normal for the system to transition to OFF when you conduct active test procedures. Holding down the OFF button for three seconds should turn AHC back on, or driving at 50 mph will turn it back on too. The system will remain in the OFF mode until you turn it back on (3 second button push ) or you exceed 50 mph, stopping and restarting the vehicle won't turn it back on, as you found out.

 

[ylexot]

Thanks Paddo. After I got my boys off to bed and my wife came home, I took the LX out for a spin. After I got the AHC back online, I parked back in the garage and took these measurements: Rows are data out from Techstream, Columns are suspension setting in sequential order.

N L N H N
FR Height 0.4 -1.6 0.3 1.8 0.3
FL Height -0.3 -2.2 -0.4 1.2 -0.4
RR Height -0.1 -1.6 0.0 1.9 -0.1
Front Pres 0.0 0.0 6.9 9.4 9.4
Rear Pres 0.0 0.0 6.9 8.5 8.5
Acc Pres 0.0 0.0 10.5 10.2 10.4

I wasn't following a prescribed test, but just being somewhat methodical and trying to characterize the system. I ran through this progression twice and got similar results both times.

Going from L to N, my pressures appear pretty close to spec: 6.9+/-0.5 MPa front and 5.6-6.7 MPa rear. I don't know though. How do these numbers look to more experienced eyes?

At minimum my next steps are to adjust the height sensors to get the front leveled and then doing a full flush and replace of my fluid.

I'm going to be mounting 180lb of bumper and winch to the front pretty soon. I'd like to have this system baselined before I add the weight and crank up the TBs to accomodate.

 

[PADDO]

Thanks Paddo. After I got my boys off to bed and my wife came home, I took the LX out for a spin. After I got the AHC back online, I parked back in the garage and took these measurements: Rows are data out from Techstream, Columns are suspension setting in sequential order.

N L N H N
FR Height 0.4 -1.6 0.3 1.8 0.3
FL Height -0.3 -2.2 -0.4 1.2 -0.4
RR Height -0.1 -1.6 0.0 1.9 -0.1
Front Pres 0.0 0.0 6.9 9.4 9.4
Rear Pres 0.0 0.0 6.9 8.5 8.5
Acc Pres 0.0 0.0 10.5 10.2 10.4

I wasn't following a prescribed test, but just being somewhat methodical and trying to characterize the system. I ran through this progression twice and got similar results both times.

Going from L to N, my pressures appear pretty close to spec: 6.9+/-0.5 MPa front and 5.6-6.7 MPa rear. I don't know though. How do these numbers look to more experienced eyes?

At minimum my next steps are to adjust the height sensors to get the front leveled and then doing a full flush and replace of my fluid.

I'm going to be mounting 180lb of bumper and winch to the front pretty soon. I'd like to have this system baselined before I add the weight and crank up the TBs to accomodate.

The center N column results are the important ones and 6.9/6.9 is a good "inline with expectations" result. But to be really useful they need be put in context with the physical height of your vehicle. So before any adjustments are undertaken I'd recommend taking front and rear centre hub to fender bottom measurements: 19.5 inches front, 20.5 rear will get you close to stock height. You can do the control arm bolt center to wheel spindle center measurements down to the mm, I have and they correlate to 19.5 and 20.5 inches. This is when you also want to identify and adjust for cross level via torsion bar adjusting, you want less than 10mm delta. The most important thing to remember here is that our AHC torsion bars effectively do two things: adjust neutral pressure and cross level. Height sensor feedback dictates front and rear height, not torsion bars and coils with packers. So, with cross level in tolerance and front/rear height in line you then focus on neutral pressures. At 6.9 front nothing to do at the moment. 6.9 rear is too high. I'm running 6.1 and it is significantly better than upper range pressures. I'd recommend new coils at a minimum, and better would be to also add trim packers, personally I'd install 30mm. At stock height and weight new coils and 10mm packers will get you down around 6.1- 6.3 range. Here is the interesting thing, when you lower the rear pressure you will also see a drop in front pressures, and vice versa so it's an iterative process of dialing in both front and rear pressures after changing coils or adding trim packers. The actual front height sensor values aren't too bad and don't appear to need adjusting, but if you do need to raise or lower the front you can do small adjustments by turning the centre threaded link cw for up, ccw for down. Rear height adjustment is via moving the lower arm link, down in the slotted slide lowers the vehicle. And absolutely replace the fluid and by default bleed the system if it hasn't been done recently. I did my first fluid change at about 60k miles and 5 years, I now change it every other year.