Line Pressure PID for 4L80?

[Supercharged111]

I suspect my line pressure is not where it should be and would like to datalog line pressure if I can. All I found was the EPC solenoid pressure (GM.tfmprs) that maxxes out at 90 psi. I believe line pressure goes from 55-230. Or do I math my way from one to the other? Or should I compare GM.tfmprs to a mechanical gauge screwed into the test port? I'm really hoping for a laptop solution here as we're about to head out with the truck and I can capture some good logs.

Editing to add this is for my 97 in sig with 411 PCM.

[Supercharged111]

Found this on the Google machine, but it's for a 4L60.

https://forum.efilive.com/showthread...ure-in-efilive

D0701 in my tune states that the torque signal pressure ranges from 0-96 and that line pressures range from 55-230, not running 130-220 like Joecar stated for the 4L60. So it sounds like I would need a mechanical gauge to observe actual line pressure. My question then becomes this: could the PCS command a certain pressure, not get that pressure, and not realize it's not getting that pressure? I suspect I'll have the privilege of messing with the valve body here in the near future, I just want to go in educated.

[nonnieselman]

Yea the PCS is only fed the current so it doesnt know if its correct pressure or not.
i use a 400psi mechanical gauge to test pressures.
Been been wanting to do this with stock pcm

download.efilive.com/Tutorials/PDF/LS1%20Fuel%20Pressure%20Sending%20Unit%20Tutorial. pdf

[Supercharged111]

On that note, it seems it'd be easiest to digest an external gauge fed into the Flash scan fact checked against the PCS data (commanded)?

[joecar]

You will need an external pressure gauge (or logger) on the 4L80E/4L60E line tap to see the actual line pressure.


As you see in the diagram below, the pid GM.TFMPRS is what the PCS is commanded to produce (see the yellow hydraulic line labelled "torque sig"), this ranges upto 96 psi.

In the diagram, 1c feeds 1a which causes 3a to regulate line pressure (red hydraulic line labelled "line"), this ranges to 250+ psi.

[nonnieselman]

On that note, it seems it'd be easiest to digest an external gauge fed into the Flash scan fact checked against the PCS data (commanded)?

Yep thats the easiest way. I got a 0-400PSI baker gauge off amazon that was liquid filled and a 10' section of -4an nitrous line. It works very good with somebody else driving tho

using a 90* 1/8" NPT to -4an fitting is the best way to get the hose attached.

[Supercharged111]

Yep thats the easiest way. I got a 0-400PSI baker gauge off amazon that was liquid filled and a 10' section of -4an nitrous line. It works very good with somebody else driving tho

using a 90* 1/8" NPT to -4an fitting is the best way to get the hose attached.

Were you able to log it too? Or just eyeballed the 2 real time? I'm hoping to use the external A/D inputs but having a hard time finding a tutorial that talks about them. I can find 400 psi oil pressure sending units all day long.

Joe that drawing is going to take me a little more to digest, but once I have my answer on actual line pressure I think it'll be even more helpful.

[joecar]

To log thru the FSV2 AD inputs, you need a 0-300+ pressure sensor, you havevto wire it same as the 2001/2002 F-car oil pressure sensor... I'll find you a link.

[Supercharged111]

To log thru the FSV2 AD inputs, you need a 0-300+ pressure sensor, you havevto wire it same as the 2001/2002 F-car oil pressure sensor... I'll find you a link.

That would be much appreciated. They appear to be 0-5V inputs? My Techedge wideband can provide a 5V input signal as well if needed.

[Supercharged111]

I think this is what I want.

https://lowdoller-motorsports.com/pr...sor-pn-8990300

Has a 3 wire connector and takes 5V in, spits out .5-4.5V. I should be able to get scaling from Holley or whoever unless it's just linear. None of those pins on the orange blocks spit out 5V, do they? Would I risk burning anything up by using the 5V supply from my wideband? I know if you leave the laptop plugged into an inverter that blows up the Flascscan. I have the 3A1.

https://wbo2.com/3a1/default.htm

Pins 8 and 9 can supply +5V and a ground, seems like the simplest way?