damian

iTrader: (2)

so i was diggin in the depths of the forum for info on transition issues and came across a funny similarity i have with another dood having transition drop...

it is tru that the main problem with transition drop is some failure of the PC system (solenoid, actuator, et) so that the secondary does not get pre-spolled....but, this other dood and i happened to notice a weird anomoly withour patterns.... as we tweaked the primary to be lower, diverting more to the secondary, it did not help the deep and slow dip of transition, HOWEVER it did tend to cause a spike after transition... but you dont notice this until you actually map your pattern out as i did...look at these graphs...both are my boost patterns with 2 dif control setups...notice how exactly the same the transition shapes is between the two...

with ball/spring pc/wg control valves:


with pfc and stock pc/wg solenoids


notice the spike after transition with either boost control setup...seems to me that this makes it obvious that the secondary is getting pre-spolled and it is either the TCA system or CRV/CCV system that is failing...either the TCA is slow to open all the way or the CRV is venting at the wrong time or the CCV is opening waaay to slow.....

on a side note, look how well the ball/spring valves control primary boost level...no spike and rock solid...


anyway, werd to plotting data and seeing garphs :-)

rotorbrain

i have an idea. . . david garfinkle tested his crv and noticed that it vents at a very low pressure. . . i wonder if it has anything to do with that. i wonder if you can replace both bov and crv with adjustable units if itll change anything.

you can blow through the crv and itll open. that says something, since your lungs cant produce any really high pressure.

hmmmm. . . something to ponder. . .

paul

damian

iTrader: (2)

what I can do to test if its the crv is swap the bov and crv for a few test runs and watch the boost pattern, if it changes then I need to look a the crv

johnchabin

iTrader: (2)

I had exactly the same problem. The hose on the Actuator side of the Turbo Control Solenoid Valve (pressure) had split (naturally, under the UIM, between the hard line and the TCS). The TCA very slowly operated with just vacuum. Additionally, when the TCS opened, it created a boost leak.

My diagnosis invloved T-ing into the TCA pressure, then vacuum line (behind & under the pressure tank is an easy place to get to them). I saw vacuum on one side at/after transistion, but no pressure on the other side.

Replaced the PITA split hose, and the problem went away.

damian

iTrader: (2)

good info john, i have tapped the tca lines before but I'll tap them again

damian

iTrader: (2)

i swapped the bov/crv, no change so the crv is ok i think...

on to the tca for tests and the ccv for more tests,...jesus i feel have tested these things like 10 times now lol hheheheheh

damian

iTrader: (2)

ok, tested the TCS pressure side and saw a 0 - 5 - 15 pattern...

0 psi until transition, then quick jump to 5psi, then a slight hesitation or 'flick' of the needle, then it raises to 15psi as the boost rises after transition.

hmm, dunno about that weird flick of the needle and wonder if it should be full psi and not start at 5 then jump up...i would think it should jump right to 15 psi right?

rotorbrain

i believe the crv and bov operate at the same pressure. so swapping them isnt gonna do a thing. you could try taking them apart and putting a harder spring in there or maybe even put an adjustable bleeder valve in the line. that way you could regulate at which time it opened. . . i think. . . i may not be thinking of something right here.

paul

damian

iTrader: (2)

ohh yeah, i know they operate exatly the same, that is why i swapped them, only to check to make sure the crv wasnt failing totaly

damian

iTrader: (2)

ok, just finished testing vac side of TCA, patter was 0 - 4-20 (vacumm)

0psi untill transition, then jump to -4 vac, slight hesitation there, then massive jump to -20 vac

smae kind of hesitation or needle 'flick as the pressure side, dunno if this is normal or not? it is almost like somthing else (ccv) is not 'acting' at the right time and firing a moment late, causing a weird 'step' that i am seeing in the tca vac/pressure

damian

iTrader: (2)

ok, tested ccv and the pattern was 20(vac)-15 psi

20 vac until transition then jumps to 15psi, however it also has this slight needle 'flick' so it goes like 20 vac, hesitation at 5vac then jump to 20 psi...

FtWorthless

Damian,

I wonder if the 0/5/15 pressure & 0/4/20 vacuum readings you get on the TCA are just seeing the TCA actually moving. 0 for both until transition, then when vacuum/pressure is applied, the pressure in the chambers is 5 pressure/4 vacuum while the thing is moving and then when it stops it builds to full pressure in the chambers of the TCA. When pressure is applied if the chamber is expanding the pressure will read artificially low. Same thing on the vacuum side - if the chamber is shrinking the vacuum will read artificially low, until the volume stabilizes. How long is it at 5 psi pressure & 4 psi vacuum? Are the times consistent? Does it seem like about the right amount of time for the TCA to move?

I'm about to do these same tests so I'll let you know what I find. On my car, the weirdest thing lately is now at transition the boost will alternate between about 6 and 10 psi a few times and the car will physically buck back and forth as it does it, before finally settling on 10 psi. Ever heard of that before? That problem is intermittent.

johnchabin

iTrader: (2)

This may be hard to see, but does the point at which you achieve 15 pressure & 20 vacuum occur at the same moment you achieve max boost?

I saw 0-0-0 on the pressure side, so it was obvious that either the solenoid was shot, or the line was bad. There was a pressure drop at transition on the pressure tank side of the solenoid, so I decided it was opening...

I've always wanted to get those darn solenoids out from under the UIM.

LAracer

This is all really good information. My boost is similar to the plot without the ball/spring valves, but of course it's all screwed up 'cos of my altitude.

Seems like now would be a good time to bring up my T-tests again:

http://www.geocities.com/laracers_vr_r1/boost_plots

I seem to be getting very similar patterns to you, except that the rpms are different, which is definitely a result of my altitude. The actual magnitudes of my pressures are different too, but the patterns seem to be pretty close.

Maybe there is no problem with your actuators and hoses; maybe the timing of the various operations is just slightly off, in which case the problem could be electrical - somewhere between the ecu and the solenoids. Just a thought.

edit: looking at your plots again, it looks like maybe the ccv is opening too soon - before the second turbo has had a chance to get moving. When you do T-tests, you might want to make careful notes about what rpm everything is happening at.

damian

iTrader: (2)

hey laracer, ur plot help me to think about this all so much, again i thank you for making htese, ...

well i tested my crv solenoid and got a 16 vac - 0 - 15psi pattern, BUT, it hesitates at 0 and builds to 15 psi, the jump from 16 vac to 0 is real quick. Dunno if this is normal, but all my stuff seems to have this hesitation in it and i cant tell if that is normal as a by product of the transition itself or if somthign is causing this becuase it is off the timing of the rest?

johnchabin

iTrader: (2)

You sure the 1" hose to your CRV isn't loose/leaking?

damian

iTrader: (2)

i replaced them recently but ill check them again...

johnchabin

iTrader: (2)

It's easy enough to check turbo precontrol after the actuator and before the solenoid (under the pressure tank). You might want to make sure it's seeing a steady build of pressure before transition. And, of course, pump the actuator open with your Mity-Vac and verify it moves (I'm sure you have done this).

I'll be under the UIM soon as my plates expired and I flunked emissions (almost 4x the legal limit for Carbon Monoxide).

damian

iTrader: (2)

yep, i checked the actuator with m-vac and it was ok, ill tap the line to the actuator to see what it is getting (it is controlled by the ball/spring valve now though, not the solenoid)

johnchabin

iTrader: (2)

The ball/spring valve sits after the actuator and the pill has been eliminated?

damian

iTrader: (2)

The pill has been eliminated but the valve is before the actuator on my setup, so it goes turbo_outlet -> valve -> actuator with the other side of the actuator capped off.

johnchabin

iTrader: (2)

So you vent the pressure back out of the actuator through the valve? Is it the same way for the wastegate?

damian

iTrader: (2)

i am not sure what you mean by this?

There is no 'vent' from the actuator, the valve see the full turbo outlet pressure, and the actuator sees whatever the valves it set to allow the actuator to see.

Both my wg and pc are setup this way.

johnchabin

iTrader: (2)

What I mean is that on the stock setup, the pill is what sees the full turbo outlet pressure, then the actuator sees the pressure as it is bled through the pill so it builds more slowly. But pressure in this line (after pill & before actuator) is also controlled (maybe 'vented' isn't the best term) by that actuator's solenoid (and its duty cycle).

If you have eliminated the solenoids from your configuration, how can you control your wastegate? Once the actuator fills up with pressure and the wastegate opens, how does it close while still under boost. And wouldn't you have to create a vacuum (or lower pressure, anyway) at the turbo outlet to evacuate the pressure from the actuator? I guess that's what I'm asking: how is the pressure evacuated from the actuator(s)?

johnchabin

iTrader: (2)

If I understand what your valves are doing (and I'm not sure I do), then what may be happening is that at transition, the CCV opens and pressure dips. You're then trying to get the boost pressure back up, but with the wastegate full open. That might be why pressure builds back so slowly - you have no duty cycle for the wastegate actuator to relieve some pressure and close back down.

Again, I'm not sure what your setup is doing...