AHC front pressure 0.0 whhaaat?

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drwapenshaw

drwapenshaw

10 Year
Joined
Nov 2, 2014
Threads
10
Messages
179
Location
Richmond VA
So I finally figured out how to get the techstream to work to measure readings before flushing the fluid.

I get 8 lines of graduation moving AHC from high to low. So I figured my readings wouldnt be too bad. Wrong!

Front pressure: 0.0
Back pressure: 6.8

0.0? Has anyone seen this before?
 
Not talking about graduations, to read the neutral pressure you put the vehicle in low and raise it to neutral, that's the pressure and height readings that matter.
 
PADDO said:
Not talking about graduations, to read the neutral pressure you put the vehicle in low and raise it to neutral, that's the pressure and height readings that matter.
Click to expand...

Ok. The AHC was blinking "off" on the dash when plugged into techstream so I thought that adjusting height during dx was not an option. I must have hit the switch accidentally. I will try doing that. It only takes 10 mins for that old OS to boot up! :-)
 
You are supposed to count graduations going from Lo to Hi, not v.v. It makes a difference in some cases.

The front and rear pressure readings through TechStream are not actually measured at the shocks, or at the actuators. The reading is a momentary check of the pump pressure exactly when the height reaches N, coming from Lo. If you want to know what happens with the front an rear pressure at different heights etc, you have to connect pressure gauges to the bleeders.

Another thing is that the grads count is valid only if the weight, the heights and the Neutral Pressure are within specs.
And the Neutral Pressure has to be checked only when the heights are within specs.

There are lots of threads in here, covering these issues and much more.
 
drwapenshaw said:
Ok. The AHC was blinking "off" on the dash when plugged into techstream so I thought that adjusting height during dx was not an option. I must have hit the switch accidentally. I will try doing that. It only takes 10 mins for that old OS to boot up! :)
Click to expand...
Make sure all doors are shut, or you'll get the blinking light forever.

Steve
 
drwapenshaw said:
Ok. The AHC was blinking "off" on the dash when plugged into techstream so I thought that adjusting height during dx was not an option. I must have hit the switch accidentally. I will try doing that. It only takes 10 mins for that old OS to boot up! :-)
Click to expand...
You want to be in AHC live, select "data list" and when you raise the vehicle from L to N the data list will repopulate with F and R height and pressure readings. These are the ones we use. As uHu correctly points out the grad count is done from L to H and all readings need to be done on level ground, no additional weight and the overall vehicle height in spec. Extra weight or too high/too low will skew pressure readings. And if your pressures are out (too high is the usual result) then your grad count won't be entirely accurate because the globes charges are compressed more than they should be.
 
Thank you Paddo. That is very helpful.

According to the ih8mud "Definitive list of AHC" and the ih8mud step by step "AHC fluid change for dummies step by step .PDF" Fuiid height is measured from high to low, but I will be happy to measure it the correct way if those ih8mud references are wrong?
 
drwapenshaw said:
Thank you Paddo. That is very helpful.

According to the ih8mud "Definitive list of AHC" and the ih8mud step by step "AHC fluid change for dummies step by step .PDF" Fuiid height is measured from high to low, but I will be happy to measure it the correct way if those ih8mud references are wrong?
Click to expand...
Yep the mud reference conflicts with FSM procedure, copy attached. I wouldn't sweat it ATT.
 

Attachments

Thanks for the help gents!

Low to high AHC lines of graduation: 10-11 , good news.

Techstream from L to N:
Front pressure: 7.8 :-( Repeat after flush: 7.3
Rear pressure 6.4 Repeat after flush: 6.8

I am getting ready to tow a trailer for work. So, I will definitely either replace the stock springs or go with the king springs or add air bags. Ultimately she will be lifted but that will be the full deal with LCA's etc, so for now I just want to be stock and be able to tow.

Got the fluid changed today, it was a lot of fun too.

Initial flush:
before.webp


Final flushes:
after.webp


Then I washed her and put a coat of wax on her. Good day!
 
Hey, I use powerade bottles to bleed into too! I like your style!
 
CanadianRockyCruiser said:
Hey, I use powerade bottles to bleed into too! I like your style!
Click to expand...

Yes, it worked very well. Using 5/16 OD (3/16 ID) tubing with a 5/16 hole drilled in the lid created a very tight seal. So tight that if I didn't vent the powerade cap before removing from the zerk it would squirt out of the tube when I disconnected it from the AHC components. Very happy one of the previous write ups mentioned wearing eye pro. I definitely needed it under there.
 
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