View Full Version : now logging actual line pressure in A6, less than 100psi in 3rd


parish8
02-20-2010, 09:12 PM
i got a pressure sensor hooked up to the test port on the tranny and am now able to log the line pressure. it does some wierd things but the bigest issue for me right now is low line pressure in 3rd gear.

on the dyno at about 600ft/lbs the tranny started slipping and so did the lock up clutch in the converter. car was locked in 3rd gear, circle D tripple disk and manualy locked tcc using hptuners non beta scan tool.

logging pcs1 appears to the the line pressure solenoid. the reported pressure and the actual pressure do not match but they do follow each other exactly. the actual line pressure is somewhere around 3 times higher than the pcs reported pressure.

at times i see 300+psi. mostly at very light load in 1st or 2nd. looking at the logs it seems like it only hits that very high pressure right after i start moving the first time after starting the car. it seems to settle down after a minute or so.

after making significant changes to several of the pressure numbers i didn't see any changes in the actual line pressure.

going from stock numbers to numbers that are 40% higher made no noticable changes to the actual line pressure on these tables. max pressure, max pressure B, max clutch. on the "max line pressure" table i took many of the numbers up a little and set the 4000rpm and 7000rpm colums at 200psi wich is a very large increase from what was in there.

i also bumped up the "oncoming pressure preset 3-4" table thinking it might be lowering the pressure getting ready for a shift?

all of my base upshift tables have been messed with a little. the injectors are a little big so the airflow tables are not exact so the tq numbers are a little low at times. we worked the tq axis so 330ft/lbs is enough to get into the highest cell where it was 440 or so before. i never see less than 330ft/lbs calculated tq. most of the pressure numbers on the higher end of those tables have been bumped up some and i never tried putting them back to stock. keep in mind most of my testing so far is just thru 3rd gear, not looking at the shifts yet.

i lowered my power as much as i could about 4psi and super rich. this allowed me to get into in 2nd gear a little. 2nd looked ok but i didn't get up into the high rpms. 150+psi for 2nd up to at least 5500rpm.

then it shifts into 3rd. pressure goes up nicely to around 200psi. the pressure goes up as soon as the tranny comands the shift but the shift happens later. by 5000rpm it starts going down and by 6000rpm it is down close to 100psi.

the pressure follows exaclty with the pcs1 comanded pressure so it appears to be a tuning thing.

without even thinking about getting thru a shift with this tranny i 1st need to be able to hold the power mid gear. what am i missing? how do i get/keep the pressures up from 5000rpm up in 3rd.

once it hits 4th pressure goes above 200psi, cant say for how long since i cant hold 4th for long without risk of going to jail. i will get some screen shots up shortly and post up my last tune.

http://www.neufamily.org/images/lockup%20pics/3rd%20gear%20line%20pressure%20down%20to%20100psi. gif

http://www.neufamily.org/images/lockup%20pics/low%20power%202-3%20and%203-4%20shift%20line%20pressure.gif

here is my latest tune >> http://www.neufamily.org/images/lockup%20pics/cam27%20final%20unlocked%2010psi%20line%20more%20p ressure%20changes%20log4.hpt

FLT
02-21-2010, 09:47 AM
This is exactly what you need to keep working on, Tom and I just talked about how important these tuning tables will be for this trans to live under your high h/p conditions. I do have someone that might be able to help you figure some of this out, I'll pass this info along and will see what he can do to help you. Good R & D Jim!

Chuck

parish8
02-21-2010, 11:30 AM
chuck, what pressure should we be looking for mid 3rd, peek tq?

is it reasonable to assume that neither the clutches in the tranny or the lock up will hold at 100psi?

parish8
02-21-2010, 01:03 PM
got another question.

assuming there isn't a tuning fix with hptuners right now. is there any reason we couldn't control this pcs1 externaly? build some kind of map based driver that would control dutycycle to that noid maped against manifold air pressure?

any sugestion on type of wire to use inside the tranny?

parish8
02-21-2010, 09:35 PM
post, post, post. i might be talking to myself but that is ok.

talking to my super geek buddy john it looks like we have a pretty easy and bad ass set up if we want to control that pcs1 noid.

using megasquirt 1 and the built in boost contol we should be able to not only control the dutycycle to that valve but use closed loop targeting based on tps and rpm or map and rpm. i can't predict any side effects of doing this. stock tranny contoler might get upset, those pressures might be that low for a reason? who knows but what i do know is i cant turn it up any higher till this is figured out.

going to give it a week or two and see if anyone has any programing sugestions for me to try.

cause4panic
02-22-2010, 07:47 AM
I have a 4 letter solution for you RMVB :D

Casey2323
02-25-2010, 09:11 AM
I have tested my line pressure just like you... I saw a quick spike just as soon as i hit the throttle to pull away from a stop.... i was after a low pressure problem that cause the lock up clutch to drag...... :punch: what about the offset voltages on the left side??... I know WILDERACING they have played with that stuff alot.... I dont have my laptop in front of me right now..... but i am going to find it

parish8
02-25-2010, 12:15 PM
I have tested my line pressure just like you... I saw a quick spike just as soon as i hit the throttle to pull away from a stop.... i was after a low pressure problem that cause the lock up clutch to drag...... :punch: what about the offset voltages on the left side??... I know WILDERACING they have played with that stuff alot.... I dont have my laptop in front of me right now..... but i am going to find it


i am not sure what offset voltages are.

T6Rocket
02-25-2010, 12:53 PM
Just curious why you expect a lock-up clutch to hold 600 ft/lb of torque? Is that extra 25 HP, or extra 2 MPH at the track (with no ET gain) that important?

Al

parish8
02-25-2010, 03:54 PM
Just curious why you expect a lock-up clutch to hold 600 ft/lb of torque? Is that extra 25 HP, or extra 2 MPH at the track (with no ET gain) that important?

Al

haha, in my truck i would see .1-.2 reduction in ET and 2mph. your talking to a drag racer. .2 is a very big deal.

T6Rocket
02-26-2010, 08:14 AM
That is a huge gain! It must pull the RPM down into a sweet spot in the power band. You locking it right after the 1-2 shift?

Al

parish8
02-26-2010, 08:36 AM
That is a huge gain! It must pull the RPM down into a sweet spot in the power band. You locking it right after the 1-2 shift?

Al

in my truck it was just a little into 3rd.

converters are tricky things. i have yet to find what i think would be a perfect set up. i have tried yank:mad:, precision, coan, and now circle D.

the yank and precision each got mutiple restalls. the coan is waaay loose. so far i like the circle D and chris is great to work with but i can tell all ready it is on the loose side. problem is i bet if i send it back then it will be too tight. when i say too loose i dont mean for daily driving. it drives great. too loose is i mash the gas and once the boost hits i never see under 5500rpm. my peek tq is likely in the 5000rpm range.

i really question if it is posiable to build a converter that will stall to over 3000rpm while only making 300ft/lbs and then be able to hold back 600-800ft/lbs without shooting right up to 5500+rpm. in my mind the best set up SHOULD be getting a converter on the loose side so you can get your best 60' and then be able to lock it up so you get to enjoy that massive tq in the 5000rpm range. i want to have my cake and eat it too.:D

it does add complication to things. i am ok with that.

for what it is worth i have locked every converter i have ever had while racing. with back to back runs i always pick up ET. not just mph. it feels slower but the clock doesn't lie. a friend of mine has a bolt on TA with a stock converter. we could consistantly pick up over .1 locking his converter up and then loose the .1 be not lettting it lock.

T6Rocket
02-26-2010, 02:38 PM
I didnt even notice you had a turbo car!

Obviously, my Toyota has a different power band, but mine also brake stalls to 3400, then goes to around 5500 when the boost hits. That means the actual stall speed is around 5500 then. That is just the nature of the beast.

If it didnt go to 5500 at WOT, the car would be a slug. I had a restall one time that was too tight (2800 on brake) and the car wouldn't hit full boost until 60 MPH! My guess is it would have slowed the car down about 3 sec in the 1/4 mile by the way it felt.

It is not recommended to lock-up a Toyota converter. It is a Precision, I ran it for a while then had it re-stalled by Midwest. It is 300 RPM tighter on the brake and has a lot more bite to it (I have to pull up the e-brake to keep the tires from spinning on the line!) I did gain 6 MPH in the 1/8th and 5 MPH in the 1/4 (.30 in ET).

Al