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.php?18451-line-pressure-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.


http://forum.efilive.com/attachment.php?attachmentid=16107&d=1384030232

[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/products/0-300-psi-pressure-sensor-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?

[joecar]

The pins on the orange blocks do not emit 5V or any voltage. They are inputs only.

[joecar]

The TE seems to be the simplest/quickest approach.

Connect the sensor to 5V and 0V from the TE.
Connect the sensor output to FSV2 AD1+.
Connect the sensor 0V/gnd to FSV2 AD1-.

Does the sensor 0-5V output range represent 0-300psi...?
We can easily make a calc pid for this.

[Supercharged111]

The TE seems to be the simplest/quickest approach.

Connect the sensor to 5V and 0V from the TE.
Connect the sensor output to FSV2 AD1+.
Connect the sensor 0V/gnd to FSV2 AD1-.

Does the sensor 0-5V output range represent 0-300psi...?
We can easily make a calc pid for this.

From what I can see, it outputs .5V-4.5V if you put the 5V into it. I figure I should call to make sure, but am assuming for the moment that that either represents 0-300psi or 300-0psi.

You're saying that the ground needs to be fed into both the FSV2 and the TE, right? I can't seem to find a good tutorial on the A/D stuff, is there a good link somewhere that I'm missing that covers the basics?

[joecar]

Yes, same ground to TE, sensor and FSV2.

[nonnieselman]

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.

If you wire that 0-300PSI sensor to the PCM like the tutorial says to do with the Fuel Pressure sensor you can datalog it and compare to the PCS signal from PCM.
The gauge i use the most is just a 400psi gauge on the end of a nitrous hose, its the easiest way to double check line pressure and such. But on my personal truck i have the 400psi sensor wired to the PCM just to datalog it.

[Supercharged111]

Next question: could I make a pid that took in the PCS's value and outputted a theoretical commanded line pressure value? I think it'd be cool to have that and the logged line pressure overlaid on the 2D screen that plots the values over time. After poking around, it seems this may be a good starting point?


Check out the example "User Defined PIDs" files in the latest EFILive release: \Documents\EFILive\V8\User Defined PIDs

If you add/change any PID definitions, you need to compile them using the \Program Files (x86)\EFILive\V8\EFILive_UserPID.exe application.

Regards
Paul

[Supercharged111]

Got the sensor, some crimpers, and 20/3 wire on the way now to make this a nice, clean install. The sensor includes a plug and pins.

[nonnieselman]

You gonna wire it thru the EGR input?

[Supercharged111]

You gonna wire it thru the EGR input?

Whatever's easier, which in the dually might be the wideband's external 5V function. I forgot all about the EGR though, that's an unused source of 5V as well. We shall see. For now I'm going to flash that new tune and see how it does on the way to the track. Lots of stuff left to do to the Camaro first. Transmission has to come back out as I screwed something up putting it together. Hopefully I get away with just yanking the rear of the case and not blowing the whole thing apart!

[dian]

for a 300psi sensor: psi = (volts- 0.5) x 75

75 being 300/4