Strange Boost Pattern And Late Transition
12-06-2002, 06:22 PM
#31
Senior Member
Thread Starter
Join Date: Oct 2002
Posts: 113
Well, slap me like a bad dawg, I did it again :redface: : I mixed up the results of the TCA and CRV tests. What the results of the TCA and CRV tests should have said was
CRV:
<3500rpm: 15"Hg (valve is open)
between 3500 and 5200rpm: 0psi (valve is closed)
>5200rpm: 7psi (valve is still closed)
(I just now double-checked this result by T-ing into the vaccum hose right at the CRV)
TCA
<5000rpm: 0psi (valve is closed)
>5000rpm: 6.5psi (valve is open maybe - I haven't checked the vacuum side yet)
I know this must be pissing off anyone following me (
P'cola, 9BASE3, 13brv3), but please guys, don't leave me. If anything, it is a sign that I need help (in many ways!).
Anyway, to answer your question P'cola, I T'd into the hose that leads from the pressure-side TC solenoid to the TC actuator. I haven't checked the vacuum side yet.
I ran one more test: T'd into the vacuum hose right on the charge control valve (CCV). Here's what I got:
<5200rpm: 10"Hg (valve is definitely closed)
>5200rpm: 7.5psi (valve is definitely open)
So the CCV appears to be working fine.
So I think the only thing I haven't checked is the vacuum side of the TCA. I guess I'll check that, then simulate the same pressure and vacuum in the garage and make sure the actuator moves.
I haven't checked anything on the wastegate system either, but you guys seemed to think that wasn't the problem, so I'll save that for last.
What are the chances that this is all because I live at 7000ft above sea level? I started a thread on this at RX7club (I know some of you have seen it), but I never really came to any conclusion.
Thanks for sticking with me guys.
CRV:
<3500rpm: 15"Hg (valve is open)
between 3500 and 5200rpm: 0psi (valve is closed)
>5200rpm: 7psi (valve is still closed)
(I just now double-checked this result by T-ing into the vaccum hose right at the CRV)
TCA
<5000rpm: 0psi (valve is closed)
>5000rpm: 6.5psi (valve is open maybe - I haven't checked the vacuum side yet)
I know this must be pissing off anyone following me (
Anyway, to answer your question P'cola, I T'd into the hose that leads from the pressure-side TC solenoid to the TC actuator. I haven't checked the vacuum side yet.
I ran one more test: T'd into the vacuum hose right on the charge control valve (CCV). Here's what I got:
<5200rpm: 10"Hg (valve is definitely closed)
>5200rpm: 7.5psi (valve is definitely open)
So the CCV appears to be working fine.
So I think the only thing I haven't checked is the vacuum side of the TCA. I guess I'll check that, then simulate the same pressure and vacuum in the garage and make sure the actuator moves.
I haven't checked anything on the wastegate system either, but you guys seemed to think that wasn't the problem, so I'll save that for last.
What are the chances that this is all because I live at 7000ft above sea level? I started a thread on this at RX7club (I know some of you have seen it), but I never really came to any conclusion.
Thanks for sticking with me guys.
12-06-2002, 10:44 PM
#32
Member
Join Date: Sep 2002
Posts: 46
Man, I don't quite know what to say, beside lay off the crack
Well, the CRV sounds perfect. The TCA pressure side seems 500 RPM late, and the CCV is 700 late. That just seems strange, though I have not actually verified these RPM levels since mine is working. On the boost gauge, my transition is exactly at 4500, so I still can't explain why yours is late.
Does your primary boost drop before 4500? I know you said it dropped from 13 to 10 by 5500, but I wondered if it happened before 4500.
Look at your CCV position, then crank the car and look at it again. Did it really move? I seem to recall reading about someone who had their door sticking open, and the primary turbo was spinning the secondary in the wrong direction. When the secondary finally got kicked in, there was a lag before it got turned back around and started making boost. As you can tell, we're dipping into the wild and wacky theory reserve.
As strange as this all is, you may very well have more than one problem.
I'll keep thinking about this.
Rusty
Well, the CRV sounds perfect. The TCA pressure side seems 500 RPM late, and the CCV is 700 late. That just seems strange, though I have not actually verified these RPM levels since mine is working. On the boost gauge, my transition is exactly at 4500, so I still can't explain why yours is late.
Does your primary boost drop before 4500? I know you said it dropped from 13 to 10 by 5500, but I wondered if it happened before 4500.
Look at your CCV position, then crank the car and look at it again. Did it really move? I seem to recall reading about someone who had their door sticking open, and the primary turbo was spinning the secondary in the wrong direction. When the secondary finally got kicked in, there was a lag before it got turned back around and started making boost. As you can tell, we're dipping into the wild and wacky theory reserve.
As strange as this all is, you may very well have more than one problem.
I'll keep thinking about this.
Rusty
12-07-2002, 09:34 AM
#33
Senior Member
Thread Starter
Join Date: Oct 2002
Posts: 113
Originally Posted by 13brv3' date='Dec 6 2002, 08:44 PM
Does your primary boost drop before 4500? I know you said it dropped from 13 to 10 by 5500, but I wondered if it happened before 4500.
This is a tough one to answer because when the primary is dropping things are moving very fast, and I'm mostly concerned with not wrecking the car
Originally Posted by 13brv3' date='Dec 6 2002, 08:44 PM
Look at your CCV position, then crank the car and look at it again. Did it really move? I seem to recall reading about someone who had their door sticking open, and the primary turbo was spinning the secondary in the wrong direction. When the secondary finally got kicked in, there was a lag before it got turned back around and started making boost. As you can tell, we're dipping into the wild and wacky theory reserve.
Ok. this is what the shop manual says too. The problem is, when I have everything together to start the car, I have a really hard time seeing the piston. Is there some trick...wait a minute, I just bought one of those little mirrors for checking the rats next - I'll try that.
Thanks Rusty
Because this might be getting confusing, I'm going to try and come up with a summary of everything I have done...and I have a new theory, which I'll get to later.
12-07-2002, 10:18 AM
#34
Senior Member
Thread Starter
Join Date: Oct 2002
Posts: 113
Ok, I have summarized things here:
http://www.geocities.com/laracers_vr_r1/bo...t_problems.html
I will paste all that into this thread for future reference once I get the problem solved.
Here's my current theory. and I think I might be getting pretty close with this one...
Precontrol is STILL not working. Why do I think this? Well, from TEST2 and TEST5 (see the webpage above) I now know the pressure on both sides of the CRV during prespool (3500 to 5200rpm). During this time the pressure is equal on both sides (0psi in hose going to the rats nest and 0psi in secondary side of the y-pipe) With equal pressure on each side, the CRV is CLOSED between 3500 and 5200. This is during pre-spool when it should be open. If the precontrol were working, there would be pressure on the secondary side of the y-pipe, which, with 0psi on the rats-nest side of the CRV, would cause the CRV to open. Thus, lack of precontrol => CRV not opening before 5200rpm.
what do you think guys?
http://www.geocities.com/laracers_vr_r1/bo...t_problems.html
I will paste all that into this thread for future reference once I get the problem solved.
Here's my current theory. and I think I might be getting pretty close with this one...
Precontrol is STILL not working. Why do I think this? Well, from TEST2 and TEST5 (see the webpage above) I now know the pressure on both sides of the CRV during prespool (3500 to 5200rpm). During this time the pressure is equal on both sides (0psi in hose going to the rats nest and 0psi in secondary side of the y-pipe) With equal pressure on each side, the CRV is CLOSED between 3500 and 5200. This is during pre-spool when it should be open. If the precontrol were working, there would be pressure on the secondary side of the y-pipe, which, with 0psi on the rats-nest side of the CRV, would cause the CRV to open. Thus, lack of precontrol => CRV not opening before 5200rpm.
what do you think guys?
12-07-2002, 12:28 PM
#35
Member
Join Date: Sep 2002
Posts: 46
I'm starting to think there's a reasonable amount of evidence to suggest that your secondary turbo is frozen up, and not spinning at all, though this wouldn't be the most common failure. Have you done one single test that shows the secondary is really producing boost? You've tested the crap out of the rest of the system, and everything works, but yet you still have no secondary boost.
Here's the logic sequence- at low rpms, boost a-plenty with just the primary. The prespool door opens, and starts bleeding off exhaust from the primary causing it to start loosing boost as rpms rise beyond 4500. The CCV opens (or not), and the TCA tries to put the secondary into full spool. Since the secondary isn't spinning, this causes a large drop in pressure, since you're only running on the primary turbo, and taking exhaust away from it to waste on the dead secondary turbo. Not the preferred way to go single :smirk:
What's the history of this car? Has it ever blown an apex seal in the past? That could certainly trash a turbo. Maybe the owner (assuming you're not the original owner) at the time didn't realize the turbo was damaged, or couldn't afford to replace them at the time. Heck, maybe the bearing is just bad. I think you'd have to remove the intake pipe on the secondary turbo to see if it spins freely.
How about this for a test- try to find a way to ty-wrap the CCV closed. Next, remove the CRV from the y-pipe hose. This should force any secondary boost to flow out the open pipe that would have gone to the CRV. I would think that you would be able to hear the boost coming out of this pipe if there is any, but I'd probably ty-wrap a piece of thin plastic wrap, over the end of the pipe for later proof of whether it produced any flow. I would NOT plug up the secondary with anything that can't be blown out if there is boost. Does anyone see anything unsafe about this proposed test?
Finally, if you prove that the turbo is free to rotate, I think you're going to have to throw in the towel, and pull that UIM for some complete testing. There's a reason Danny puts the hose job as one of the first items on his troubleshooting list. I tried to avoid doing it, but in the end, that's what fixed my problem.
As always, good luck,
Here's the logic sequence- at low rpms, boost a-plenty with just the primary. The prespool door opens, and starts bleeding off exhaust from the primary causing it to start loosing boost as rpms rise beyond 4500. The CCV opens (or not), and the TCA tries to put the secondary into full spool. Since the secondary isn't spinning, this causes a large drop in pressure, since you're only running on the primary turbo, and taking exhaust away from it to waste on the dead secondary turbo. Not the preferred way to go single :smirk:
What's the history of this car? Has it ever blown an apex seal in the past? That could certainly trash a turbo. Maybe the owner (assuming you're not the original owner) at the time didn't realize the turbo was damaged, or couldn't afford to replace them at the time. Heck, maybe the bearing is just bad. I think you'd have to remove the intake pipe on the secondary turbo to see if it spins freely.
How about this for a test- try to find a way to ty-wrap the CCV closed. Next, remove the CRV from the y-pipe hose. This should force any secondary boost to flow out the open pipe that would have gone to the CRV. I would think that you would be able to hear the boost coming out of this pipe if there is any, but I'd probably ty-wrap a piece of thin plastic wrap, over the end of the pipe for later proof of whether it produced any flow. I would NOT plug up the secondary with anything that can't be blown out if there is boost. Does anyone see anything unsafe about this proposed test?
Finally, if you prove that the turbo is free to rotate, I think you're going to have to throw in the towel, and pull that UIM for some complete testing. There's a reason Danny puts the hose job as one of the first items on his troubleshooting list. I tried to avoid doing it, but in the end, that's what fixed my problem.
As always, good luck,
12-07-2002, 02:15 PM
#36
Senior Member
Thread Starter
Join Date: Oct 2002
Posts: 113
All that makes alot of sense, unfortunately. The history of the car is that I'm the 4th owner, but it only has 21k miles. I paid dearly for that mileage, and I'll be pissed if the turbo really is busted (although I guess its my fault for not doing a thorough boost test when I bought it - lesson to potential buyers).
I'll check whether the 2nd turbo spins. It'll have to be tomorrow (or maybe just very late tonight).
Thanks again rusty.
I'll check whether the 2nd turbo spins. It'll have to be tomorrow (or maybe just very late tonight).
Thanks again rusty.
12-07-2002, 06:12 PM
#37
Senior Member
Thread Starter
Join Date: Oct 2002
Posts: 113
I took off the inlet to the secondary compressor. I can see the blades using a mirror - they are all there . It spins ok. How freely should it spin? I can turn it with my fingers, but it doesn't keep spinning much (if any) after I let go (it's not on bearings, right?). There is a little play, but I hear that is normal. Is there anything else I should look for while I have access to the compressor?
I never checked the pills in the PC and wastegate. I need to do that next.
I never checked the pills in the PC and wastegate. I need to do that next.
12-07-2002, 06:44 PM
#38
Member
Join Date: Sep 2002
Posts: 46
That sounds like a good turbo to me, but to be sure, maybe you should send those 21k turbos to me for some testing :smirk:
I can't believe you've made it this far without checking pills. What are we going to do with you :stickpoke:
From what I've read, leaving out the pills is a common mistake when changing hoses, but yours probably haven't been touched. I forget what year car you have, but later years didn't have pills. Instead, the restriction was built into the actuators. If the pills were removed, I think you'd be limited to 7 psi of boost, which is the spring pressure of the wategate actuator. Don't even think about asking me if the spring pressure changes with altitude
Not much to do now but suck it up, order some silicone or viton hose, and yank that UIM. In the end, it will be far less trouble than you've already gone through.
I can't believe you've made it this far without checking pills. What are we going to do with you :stickpoke:
From what I've read, leaving out the pills is a common mistake when changing hoses, but yours probably haven't been touched. I forget what year car you have, but later years didn't have pills. Instead, the restriction was built into the actuators. If the pills were removed, I think you'd be limited to 7 psi of boost, which is the spring pressure of the wategate actuator. Don't even think about asking me if the spring pressure changes with altitude
Not much to do now but suck it up, order some silicone or viton hose, and yank that UIM. In the end, it will be far less trouble than you've already gone through.
12-08-2002, 10:14 AM
#40
Senior Member
Thread Starter
Join Date: Oct 2002
Posts: 113
Hehe ,
And the funny thing is that despite this boost problem, the car feels REALLY fast. I mean, I would never have suspected a problem if I hadn't installed the boost gauge. Maybe the best fix is to remove the boost gauge .
I will check the pills today, I promise.
Looking at the results of my CRV T test, notice the pressure changes once at 3500rpm and then again at 5200. I think the 3500 change happens when the CR solenoid clicks (so I'm saying it clicks early, unlike everything else which clicks late). Since, after the solenoid clicks, the hose I T'd into is reading essentially the same as the secondary side of the y-pipe, the pressure is 0psi, and the change at 5200 is the change in y-pipe pressure at 5200 (from 0 to 7psi). Now, since 0psi after 3500 closes the CRV, that's not good for prespool. I don't see exactly how that causes the decline in primary boost (although fluid dynamics is a strange thing so it might lead to that). It could definitely cause the low secondary. But the late transition? I'm thinking that has to be caused by the same thing that clicks the CR solenoid early; a sensor for the computer?
I'm going to do what you said, which is to force the CRV open and check things out. If my theory is correct, I *should* see evidence of prespool in the secondary side of the y-pipe.
......and, I'm getting ready to order the hose. I have a thread going at the other place about whether silicone holds up over time. I'd really like some pretty colored hoses. But I don't have any good data points telling me that silicone won't disintigrate (like that silicone vs Viton vs rubber test that someone did) after a few years. Looks like it'll be boring (and expensive) old black Viton.
As always, thanks a bunch.
And the funny thing is that despite this boost problem, the car feels REALLY fast. I mean, I would never have suspected a problem if I hadn't installed the boost gauge. Maybe the best fix is to remove the boost gauge
I will check the pills today, I promise.
Looking at the results of my CRV T test, notice the pressure changes once at 3500rpm and then again at 5200. I think the 3500 change happens when the CR solenoid clicks (so I'm saying it clicks early, unlike everything else which clicks late). Since, after the solenoid clicks, the hose I T'd into is reading essentially the same as the secondary side of the y-pipe, the pressure is 0psi, and the change at 5200 is the change in y-pipe pressure at 5200 (from 0 to 7psi). Now, since 0psi after 3500 closes the CRV, that's not good for prespool. I don't see exactly how that causes the decline in primary boost (although fluid dynamics is a strange thing so it might lead to that). It could definitely cause the low secondary. But the late transition? I'm thinking that has to be caused by the same thing that clicks the CR solenoid early; a sensor for the computer?
I'm going to do what you said, which is to force the CRV open and check things out. If my theory is correct, I *should* see evidence of prespool in the secondary side of the y-pipe.
......and, I'm getting ready to order the hose. I have a thread going at the other place about whether silicone holds up over time. I'd really like some pretty colored hoses. But I don't have any good data points telling me that silicone won't disintigrate (like that silicone vs Viton vs rubber test that someone did) after a few years. Looks like it'll be boring (and expensive) old black Viton.
As always, thanks a bunch.