I finally got around to taking the car out on it's first drive with the 4L80E after verifying fluid level was correct. I kept the RPM's under 6000 and the trip short. I did not go full WOT. TCC lockup is working in 4th (currently not commanded to ever lock in 3rd), and all the shifts are smooth. Some slight tweaks needed to shift points but nothing major. Overall I'm very happy with it other than the high pressure which will be addressed. Everything seems to be functioning as it should. 3500 stall, single disc lock up, 4.10 gears. All of which will be replaced when the new engine combo/turbo setup goes in.

I wanted to make sure the 4L80E was good on the H/C/I LS1 setup for now and only change one major variable at a time before mating it with the higher hp setup.

The 4L80E has a Jakes D3 with EPC block plug used for fixed line pressure, and I'm running a sonnax LB1 boost valve, LB1 boost sleeve, a CK purple spring rated for 190 PSI, stock PR valve, small stock spring, and line to lube drilled 0.093

I had read that using a sonnax LB1 spring can result in erratic line pressure, but that running the sonnax LB1 boost valve and LB1 sleeve with a different spring would be fine. My thought was to not use the long Jakes D3 spring that came with the brake as that would be too much pressure for the current combo at the lower power level and instead go with a less stiff spring. Well with the combo in bold above, I'm seeing idle pressures averaging around 162 with the trans temp at about 140, but much higher pressures with increased RPM hovering in the 200's. Temp never went above 175 with the trucool 40k. Running a temp sensor in the pan on a gauge as well. Mechanical gauge bounces around 170-190 when idling hot in P, N, D. Reverse functions as it should with the transbrake activation, and obviously pressures are much higher in rev maxing the gauge at 300 psi.

The AFL in the VB vac tested at 18 Hg. It had a transgo AFL installed upon receipt. My findings for vac testing the pump after replacing all the end plugs with o-ringed end plugs were applicable were:





HP Tuners log file is here: https://drive.google.com/file/d/1JeW...usp=share_link
Video of log here:
So my question is based on these results and the pressures being so high, should I swap out the purple spring with a stock spring? Swap the LB1 boost valve and LB1 sleeve for stock? Yes the instructions that came with the VB call for using the long spring that came with it, but my thinking there is that I would run that with the higher hp combo, and shoot for 210-215 on this combo. Didn't know that in a fixed line pressure setup, the purple spring rated for 185-190 PSI when paired with LB1 boost/sleeve results in 240 PSI while cruising at 2200 rpm and 50 mph in 4th. At this point I'd like to change it up so that we are at 185-190 PSI max. Not going to be needing the t-brake to function perfectly until the new engine combo goes in anyway so I would think those pressures would be fine.

 

240 psi will kill the case lugs on a 1-2 shift pretty quick.

You've got a ton of mix and match parts. Pick a method and use matched parts.

 

My assumption that purple spring + LB1 sleeve and LB1 boost valve (based on what I had read) would put me around 200-205 PSI was not correct but that info came from a non fixed line pressure setup which was overlooked. (LB1 adding 10-15 psi)

 

I use the CK purple spring with the stock boost valve quite a bit. generally it gets about 70 hot idle, 190 max fwd gears. (with EPC functional)

I think using it with the increased surface sizes in the sonnax boost valve is giving you the high line pressure. When I use an LB1 I usually use the stock 80e spring with it. It gives about the same pressures as a CK Purple/stock boost valve but the line rise response to torque signal oil is much sharper, still quite tuneable with the EPC though.

Now someone straighten me out here if I misspeak, but the epc plug essentially maxes torque signal oil to the boost valve and I reckon thats where your high line pressure is coming from.

 

But even with the increased surface sizes, 240 seems excessive but maybe not when the epc plug is used.

 

This is pretty simple math
But the EPC plug alone is not the cause of your overpressure issue
If you run the math...you'll see that

Not sure what the CK spring weighs, but it's obviously too much for what you've got going on

The valve body kit came with a spring and instructions...why have you deviated from that if you weren't precisely sure of the result you would get?

 

Doug hit the nail on the head. The epc plug gives full torque signal. It’s like grinding a flat on oem valve.

 

The instructions I received specified use of an EPC with the middle land ground, but I then received word that the use of an EPC plug is better and more consistent. I should have just simply used the EPC plug and followed the instructions and changed nothing else. Going to try Jakes spring, OE sleeve and OE boost valve with the EPC block off plug next. Read information online without fully understanding how the end result is impacted as a result of the combination of parts. Another lesson learned, but nothing is damaged.

 

There is much discussion on this forum and others about the epc plug vs the stock epc solenoid with the center land ground away
The argument I hear is that the epc by nature bleeds off a little of the AFL oil and therefore does not send the same signal to the booster.
I have a couple issues with this argument on principle and in practice

1st. The AFL valve and entire circuit is a leak. that's its inherent design. The AFL circuit is regulated via a spring that controls the pressure to *around* 95 psi...give or take based on bore wear.
The entire circuit is being bled off all the time. Shift solenoids leak off the AFL oil. The epc is actually the smallest leak of them all. The AFL valve's job is to keep that circuit charged with a consistent pressure. so unless you have a junk epc that's puking all the tq signal oil...or an afl bore that's just whooped...the plug isn't going to make huge changes

2nd let's say there WAS a leak...just for sake of argument. How big must this leak be for someone to argue it's affect on the overall line pressure. Every 1psi change of AFL delivered to boost valve will deliver 1.40 psi change (stock boost) or 1.51 psi change (LB1 boost)
so...5 psi leak at the EPC...fix that with the plug and you'd gain roughly 7psi total line
10 psi leak...fix it...gain 14 psi
so on and so fourth

I find it highly unlikely that the leak is that significant to have pressures shoot up to an unsafe value like you're seeing.
And since the entire AFL circuit is built and designed to regulate pressure in the circuit despite leaks...I'd say the epc leak is not making as big of swings as some say.

and that brings me to the "in practice" issue I mentioned...in practice I've done quite a few of these and have not had anywhere near the results you're having
To my knowledge @jakeshoe hasn't had to re-spec springs or make any big changes in his setup after he started making the epc plugs. And with the volume of units his shop builds, and dyno's each and every one...he'd quickly see a 15-20 psi increase in overall line with the same combo and only changing an epc plug

Moral of the story...a ground epc and a nice billet plug should act exactly the same...they certainly aren't going to account for 40psi of overpressure that you're seeing in your trans

 

The reason we started producing the EPC plugs again (we had these made about 10 years ago when the D3 was new) was because we see on the dyno that occasionally an EPC will be "dead".
EPC is a pintle valve with a solenoid to pull it open. If it gets trash in the valve or for some reason hung open, it will bleed pressure. If it's not damaged, it seals pressure off and power applied to it, opens it to exhaust. This leaks AFL oil pressure and creates torque signal oil that goes to the boost valve and accumulator valve. Increased pressure at the boost valve ramps up line, increased pressure at the accumulator ramps up accumulator circuit pressure for firmer shifts.

An EPC plug itself will not increase line pressure unless you are comparing it to a bad EPC that is constantly exhausting line.

The boost valve diameter, spring pressure, torque signal pressure, and PR valve diameter ultimately make line pressure.
An EPC plug can't cause increased torque signal pressure unless it's resolving a leak that the EPC had because it was faulty.

I could reserve EPC plugs for use in our builds and save $. However we dyno everything so a bad EPC would get caught. We send a VB out to the end user with instructions to grind the EPC and if they have a bad EPC, they burn up the unit. Guess who gets the blame? We didn't provide the EPC, we aren't the ones who failed to monitor pressure...

 

ah so it's essentially the same as cutting the end off the noid, pulling the piston and tapping for a set screw. good to know.

Dino, man I'm not sure how you're getting 240psi out of a CK purple spring with a sonnax boost valve. The PR valve has gotta be hanging up or something.

I would set it up just like normal for a jake's VB, sonnax boost valve, jake's long skinny-wire spring, epc plug. check that PR valve stokes nice n easy. gotta be something simple.

 

Yes
just loops the AFL oil right into tq signal oil
feeds it right to the booster

 

I was just going to run the oe boost valve/oe boost sleeve and jake's long skinny-wire spring with the epc plug and an oe PR valve and omit the sonnax stuff. I'll start with this and see what pressures are.

 

right. set it up just how Jake's kit comes out of the box. Never had an issue doing it that way. usually see right at 200psi max and line pressure is very steady.

 

Update:

The setup in the PR bore was changed to everything stock with the exception of a sonnax o-ring end plug. So stock boost valve, stock boost spring, stock sleeve, stock PR valve, etc. I wanted to establish a baseline and see where pressures would be keeping the PR bore with OE parts.

As mentioned above, the setup has a 0.093 line to lube drilled and blocked EPC plug with Jakes D3 Plus.

The PR valve assembly in the bore is all installed in the correct orientation
The boost valve moves nicely inside the sleeve
The PR valve moves nicely inside the bore
Reverse servo cover was sanded, new gasket used, air check on the case for that reverse servo was good
The old LB1/ck purple spring setup came right out of the bore on the lift with no issues.

I'm getting a ton of noise on the pressure readings in the logs. Going to try a new sensor and hook up the mechanical gauge again to the T fitting to monitor simultaneously, mechanical and electrical to verify sending unit is correct. It's a pain getting to it in the trans tunnel, so I was hoping that by swapping everything in the PR bore to stock I'd be able to first see something good just when logging with the transducer, but I'm seeing pressures that are all over.

The trans shifts perfect, and it drives perfect. Lockup is working as it should. Car pulls hard. Tried to get the trans warm but at 40 degrees out and a trucool 40k, trans temps stayed under 130.

Could there be a leak in the forward circuit causing the high pressures? (assuming they are in fact still high after replacing the sending unit)
Pressure got higher when increasing RPM in park, D4 stayed lower, similar to the other forward gears with higher RPM (not pictured)
At this point the data provided by the transducer is suspect but trends can be seen from the data.

Neutral Idle



Reverse



D3 and D4 idle



D2 idle



Park higher RPM



D4 higher RPM

 

remind us what sensor you're using?
how do you have it scaled

on alot of these cheaper sensors, you'll see that much noise in the graph, and the scaling is vital.
0.1 volt of miss-scaling is 5psi
verify it with a good quality mechanical gauge...it'll be ok

 

I'm using a 0-300 PSI Pressure Sensor PN: 7990300 from Low Dollar Motorsport. It is NOT the more expensive oil filled silicon variant which is 8990300-0-300 that they sell.
I've seen someone else's log using a cheap $16 sensor on Amazon and the data has far less noise than mine, and that's with all the parameters in the HP tuners software being set exactly the same as mine. (100ms period, "average")

He's using this one:
So based on the 0.5 - 4.5v / 0 - 300 PSI range, formula can either be (volts * 75) - 37.5 = PSI or (volts / .0133333333) - 37.5 = PSI
I've checked it both ways, and both give the same amount of noise as one would expect since they are the same formula.
Note that for the images in post #15, I'm not using the average function seen in the image below. The sensor is set at period of 0ms and "none".
When I went to log it again at the period set to 100ms and "average" the PSI numbers for the average function were even higher and still it had more noise than the log of someone else I was comparing it to. It doesn't make sense. You can see in the image below, white is 100ms and "average" and yellow is 0ms and "none". Note the large difference in PSI.
What's the trick to getting a smooth reading without so much noise caused by pump pulses?
I have the mechanical gauge pictured below (will replace with MAC or OTC) when I originally tested it with the CK purple spring/LB1 setup. The numbers were similar (higher than 220) logging them simultaneously between digital and mechanical. Plan is to hook up the mechanical gauge again as maybe the transducer went bad somehow between the swapping of the parts in the pump bore.


















Image above taking from a video of my log file. https://drive.google dot com/drive/u/1/folders/1_UExMx3nQTfdDdO5nTarC_gruJ8R_rGQ
Those that wish to view will need to replace "dot" with "." and download the file as it won't play directly.

 

Just put a mechanical gauge on it and quit dicking around with making it more difficult than it needs to be.

 

you should be able to smooth the signal nicely with a low-pass filter, if you play around a bit. i would start with 1kohm and1µf (no expert here).

 

wish I could like this post more than once