Boost Control Problem - Advice Needed
Oct 4, 2013, 12:39 PM
#16
And at 99%, because of the latency of BCS, it's not building pressure in the wastegate line and stays shut like it would be at 100%. So at 98%, if it's opening, the pressure created applies a force on the mac valve that make it stay opened longer than 2%. Like there is a minimum physical time the BCS can open (pressure delays the valve from closing). That's why the difference in wastegate efficiency is so big, so when the wastegate shuts, you either overcome a boost leak, or something else is happening in there. Don't know if i'm clear.
(When I say open or closed, see it as you will: it's a 3 way valve. )
(When I say open or closed, see it as you will: it's a 3 way valve. )
Oct 4, 2013, 12:56 PM
#17
My FP 25psi WGA does that too. I think it is boost creep from having it preloaded too much. I just always go with lower WGDC there to fix it.
Also, some of what Domyz is saying above is true. MRFRED once mentioned that the boost control system actually works on 2 WGDC steps. ie 96% is 96% but 97% with be 98%, 98% will be 98%, but 99% will be 100%. Its because ECUFlash has the incorrect scaling for WGDC according the MRFRED. Someone should fix that.
Also, some of what Domyz is saying above is true. MRFRED once mentioned that the boost control system actually works on 2 WGDC steps. ie 96% is 96% but 97% with be 98%, 98% will be 98%, but 99% will be 100%. Its because ECUFlash has the incorrect scaling for WGDC according the MRFRED. Someone should fix that.
However, to hold more boost out the top with a lower WGDC would require more WGA preload would it not? I hoped that with the FP 25 psi WGA preloaded 6mm (1/4 "), and an FP Green HTA73, that I should be able to hold more boost out the top than 25 psi.
Can you comment on what WGDC% you use and what boost levels you are seeing out the top on your own setup? If I don't find a massive boost leak this weekend, I'm beginning to suspect that FP may have put the wrong spring in my WGA. When I tested boost levels with spring pressure alone I got 21 psi - sounds low for a 25 psi WGA does it not?
Oct 4, 2013, 05:33 PM
#18
Thanks for chipping in Jay. It's good to hear that someone else has experienced the same unusual behavior. It makes sense that the scaling could be to blame for the non-linear boost response.
However, to hold more boost out the top with a lower WGDC would require more WGA preload would it not? I hoped that with the FP 25 psi WGA preloaded 6mm (1/4 "), and an FP Green HTA73, that I should be able to hold more boost out the top than 25 psi.
Can you comment on what WGDC% you use and what boost levels you are seeing out the top on your own setup? If I don't find a massive boost leak this weekend, I'm beginning to suspect that FP may have put the wrong spring in my WGA. When I tested boost levels with spring pressure alone I got 21 psi - sounds low for a 25 psi WGA does it not?
However, to hold more boost out the top with a lower WGDC would require more WGA preload would it not? I hoped that with the FP 25 psi WGA preloaded 6mm (1/4 "), and an FP Green HTA73, that I should be able to hold more boost out the top than 25 psi.
Can you comment on what WGDC% you use and what boost levels you are seeing out the top on your own setup? If I don't find a massive boost leak this weekend, I'm beginning to suspect that FP may have put the wrong spring in my WGA. When I tested boost levels with spring pressure alone I got 21 psi - sounds low for a 25 psi WGA does it not?
Its seems to me, if you wanted your boost to keep tapering at the rate it is, lower your WGDC duty cycle at 7000 and 7500. Run like 90%WGDC at 7k and 85%WGDC at 7.5K (or something around there). No need to preload your wastegate more.
Oct 4, 2013, 07:14 PM
#20
I missed that you said your trying to eliminate the taper. To do so, just use whatever WGDC you need. Up at 7/7.5K, you"ll have non liner WGDC, most likely with a dip to fix the dip. And you may have to preload your WGA more or find your issue (read below(
Plus, Im gonna have to agree with 90zcrex, and say you may have a boost leak or a leaking DV. You should be able to hold more boost with 100% WGDC.
Plus, Im gonna have to agree with 90zcrex, and say you may have a boost leak or a leaking DV. You should be able to hold more boost with 100% WGDC.
Oct 4, 2013, 11:42 PM
#22
I missed that you said your trying to eliminate the taper. To do so, just use whatever WGDC you need. Up at 7/7.5K, you"ll have non liner WGDC, most likely with a dip to fix the dip. And you may have to preload your WGA more or find your issue (read below(
Plus, Im gonna have to agree with 90zcrex, and say you may have a boost leak or a leaking DV. You should be able to hold more boost with 100% WGDC.
Plus, Im gonna have to agree with 90zcrex, and say you may have a boost leak or a leaking DV. You should be able to hold more boost with 100% WGDC.
I will leak test the entire system tomorrow and post what I find. I called FP today and they said that with four full turns (4 mm) of preload, the FP 25 psi WGA should hold 23-24 psi before it starts to open. They also said 8 full turns (8 mm) of preload requires 27-28 psi before it starts to open.
I will get a bicycle pump with a gauge on it to bench test the WGA and see at exactly what pressure it opens with my current 6 turns (6 mm) of preload. I'll also check the serial number they gave me for the 25 psi WGA to make sure that's what I've got.
Next I'll run a line from J-pipe nipple direct to the WGA to see what boost I get out the top. That should take care of boost leaks, my crushed IX DV real crack pressure, and actual WGA behavior under boost without the GM 3-port.
Finally I'll add the GM 3-port back in to the circuit at 0% WGDC, and see what psi I get out the top. It should be the same as without the 3-port - right?. The last step will be to add back increasing levels of WGDC and see how boost responds.
If you can think of any other diagnostic steps I should take to isolate cause please let me know.
Last edited by CDrinkH2O; Oct 4, 2013 at 11:54 PM.
Oct 5, 2013, 10:58 AM
#26
Thanks for your advice guys. I can hold 32 psi out the top if I raise WGDC to 100%. It's the spike from 25 psi at 98.5% to 32 psi at 100% that I'm struggling to control.
I will leak test the entire system tomorrow and post what I find. I called FP today and they said that with four full turns (4 mm) of preload, the FP 25 psi WGA should hold 23-24 psi before it starts to open. They also said 8 full turns (8 mm) of preload requires 27-28 psi before it starts to open.
I will get a bicycle pump with a gauge on it to bench test the WGA and see at exactly what pressure it opens with my current 6 turns (6 mm) of preload. I'll also check the serial number they gave me for the 25 psi WGA to make sure that's what I've got.
Next I'll run a line from J-pipe nipple direct to the WGA to see what boost I get out the top. That should take care of boost leaks, my crushed IX DV real crack pressure, and actual WGA behavior under boost without the GM 3-port.
Finally I'll add the GM 3-port back in to the circuit at 0% WGDC, and see what psi I get out the top. It should be the same as without the 3-port - right?. The last step will be to add back increasing levels of WGDC and see how boost responds.
If you can think of any other diagnostic steps I should take to isolate cause please let me know.
I will leak test the entire system tomorrow and post what I find. I called FP today and they said that with four full turns (4 mm) of preload, the FP 25 psi WGA should hold 23-24 psi before it starts to open. They also said 8 full turns (8 mm) of preload requires 27-28 psi before it starts to open.
I will get a bicycle pump with a gauge on it to bench test the WGA and see at exactly what pressure it opens with my current 6 turns (6 mm) of preload. I'll also check the serial number they gave me for the 25 psi WGA to make sure that's what I've got.
Next I'll run a line from J-pipe nipple direct to the WGA to see what boost I get out the top. That should take care of boost leaks, my crushed IX DV real crack pressure, and actual WGA behavior under boost without the GM 3-port.
Finally I'll add the GM 3-port back in to the circuit at 0% WGDC, and see what psi I get out the top. It should be the same as without the 3-port - right?. The last step will be to add back increasing levels of WGDC and see how boost responds.
If you can think of any other diagnostic steps I should take to isolate cause please let me know.
Also, IMO, FP is wrong with what they say about their 25psi WGA. I have preloaded a couple FP 25psi WGA all the way, tight as they can be preloaded and they all only give about 21-23psi.
To see if its your DV, thats easy. Just do a boost leak test, leaving the DV installed onto the UICP. If it leaks, you'll feel/hear it come out the open end (the end that went into the intake). Just make sure to test all the way to 30psi.
All in all, I think its the GM 3port thats the issue here.
Oct 7, 2013, 10:42 PM
#27
OK, so there are no charge circuit leaks up to 30 psi. My crushed IX DV doesn't leak at 30 psi. It cracks at 32 psi.
The pre-loaded (6 full turns) FP 25 psi WGA starts to open at 22-23 psi tested using a bicycle pump and guage.
Running a line direct from J-pipe to WGA gives me 21 psi boost out the top.
The GM 3-port checks out OK. When activated (using Evoscan) boost input port connects direct to WGA output port. When inactive WGA port connects directly to vent port.
After adding the 3-port back into the BCS, running 0%WGDC gives me 21-22psi out the top.
When I increase WGDC from 98.5 to 99% I still get the 4-5psi spike.
So that removes boost leaks, DV leaks and the 3-port from potential causes of this problem. It also still leaves me trying to figure out how to solve this one.
Possible ways to regain linear boost control as the 3-port reaches 100%:
1. WGA with stronger spring? - TurboSmart 26 psi WGA (Part# TS-0601-2222)
2. GrimmSpeed 3-port - Jay I'm not sure how this will change linear response near 100% compared to the GM 3-port - can you comment?
3. Open up the waste gate port merge on my Megan O2 to reduce turbine backpressure just before the waste gate closes.
If you have any other suggestions - I'm all ears.
The pre-loaded (6 full turns) FP 25 psi WGA starts to open at 22-23 psi tested using a bicycle pump and guage.
Running a line direct from J-pipe to WGA gives me 21 psi boost out the top.
The GM 3-port checks out OK. When activated (using Evoscan) boost input port connects direct to WGA output port. When inactive WGA port connects directly to vent port.
After adding the 3-port back into the BCS, running 0%WGDC gives me 21-22psi out the top.
When I increase WGDC from 98.5 to 99% I still get the 4-5psi spike
.So that removes boost leaks, DV leaks and the 3-port from potential causes of this problem. It also still leaves me trying to figure out how to solve this one.
Possible ways to regain linear boost control as the 3-port reaches 100%:
1. WGA with stronger spring? - TurboSmart 26 psi WGA (Part# TS-0601-2222)
2. GrimmSpeed 3-port - Jay I'm not sure how this will change linear response near 100% compared to the GM 3-port - can you comment?
3. Open up the waste gate port merge on my Megan O2 to reduce turbine backpressure just before the waste gate closes.
If you have any other suggestions - I'm all ears.
Oct 8, 2013, 01:30 AM
#28
OK, so there are no charge circuit leaks up to 30 psi. My crushed IX DV doesn't leak at 30 psi. It cracks at 32 psi.
The pre-loaded (6 full turns) FP 25 psi WGA starts to open at 22-23 psi tested using a bicycle pump and guage.
Running a line direct from J-pipe to WGA gives me 21 psi boost out the top.
The GM 3-port checks out OK. When activated (using Evoscan) boost input port connects direct to WGA output port. When inactive WGA port connects directly to vent port.
After adding the 3-port back into the BCS, running 0%WGDC gives me 21-22psi out the top.
When I increase WGDC from 98.5 to 99% I still get the 4-5psi spike.
So that removes boost leaks, DV leaks and the 3-port from potential causes of this problem. It also still leaves me trying to figure out how to solve this one.
Possible ways to regain linear boost control as the 3-port reaches 100%:
1. WGA with stronger spring? - TurboSmart 26 psi WGA (Part# TS-0601-2222)
2. GrimmSpeed 3-port - Jay I'm not sure how this will change linear response near 100% compared to the GM 3-port - can you comment?
3. Open up the waste gate port merge on my Megan O2 to reduce turbine backpressure just before the waste gate closes.
If you have any other suggestions - I'm all ears.
The pre-loaded (6 full turns) FP 25 psi WGA starts to open at 22-23 psi tested using a bicycle pump and guage.
Running a line direct from J-pipe to WGA gives me 21 psi boost out the top.
The GM 3-port checks out OK. When activated (using Evoscan) boost input port connects direct to WGA output port. When inactive WGA port connects directly to vent port.
After adding the 3-port back into the BCS, running 0%WGDC gives me 21-22psi out the top.
When I increase WGDC from 98.5 to 99% I still get the 4-5psi spike
.So that removes boost leaks, DV leaks and the 3-port from potential causes of this problem. It also still leaves me trying to figure out how to solve this one.
Possible ways to regain linear boost control as the 3-port reaches 100%:
1. WGA with stronger spring? - TurboSmart 26 psi WGA (Part# TS-0601-2222)
2. GrimmSpeed 3-port - Jay I'm not sure how this will change linear response near 100% compared to the GM 3-port - can you comment?
3. Open up the waste gate port merge on my Megan O2 to reduce turbine backpressure just before the waste gate closes.
If you have any other suggestions - I'm all ears.
There is two ways to fix this. Either add a "boost pill". This will make a restriction and make the boost controller have more "range". Make sure you lower your WGDC drastically if you do this method. Depending on the size boost pill you use, you may only need 50-70WGDC to see your desired boost up top.
The second way would be to try a Grimmspeed 3port solenoid. I believe the GS 3port has a "bigger" range ie 95% on GS is 30psi, 95% on GM is 24psi. There is a chance Im wrong about the "bigger" range, but I think it will work.
The easiest way would be the boost pill. You can buy a boost pill for like 15-20 bucks shipped. Or you can probably just use the stock one out of the stock boost lines. If it was me, I'd try the boost pill out of the stock lines. Free/cheap and easy. Use the pill by the wastegate, not by the solenoid (The pill by the wastegate has a smaller hole, which will give you more "range", even though the solenoid pill may work fine too).
EDIT: Your #3 idea wont help. Opening up the merge hole in the O2 housing will give you less "creep" ie less boost up top
Last edited by Boosted Tuning; Oct 8, 2013 at 01:40 AM.
Oct 9, 2013, 08:58 AM
#29
This is whats happening, IMO. when you have 98% or 98.5%, the ECU is giving it 98%, but soon as you go to 99%, the ECU gives its 100%. Now even though 100 is only 2% above 98%, it means the valve is fully open and venting 100% of the air. So since it vents 100% of the air, the turbo is gonna run the most it can up top, which is 30psi. Basically you have ran out of range. 98% =25psi, but 100% is fully open and lets turbo do its max.
There is two ways to fix this. Either add a "boost pill". This will make a restriction and make the boost controller have more "range". Make sure you lower your WGDC drastically if you do this method. Depending on the size boost pill you use, you may only need 50-70WGDC to see your desired boost up top.
The second way would be to try a Grimmspeed 3port solenoid. I believe the GS 3port has a "bigger" range ie 95% on GS is 30psi, 95% on GM is 24psi. There is a chance Im wrong about the "bigger" range, but I think it will work.
The easiest way would be the boost pill. You can buy a boost pill for like 15-20 bucks shipped. Or you can probably just use the stock one out of the stock boost lines. If it was me, I'd try the boost pill out of the stock lines. Free/cheap and easy. Use the pill by the wastegate, not by the solenoid (The pill by the wastegate has a smaller hole, which will give you more "range", even though the solenoid pill may work fine too).
EDIT: Your #3 idea wont help. Opening up the merge hole in the O2 housing will give you less "creep" ie less boost up top
There is two ways to fix this. Either add a "boost pill". This will make a restriction and make the boost controller have more "range". Make sure you lower your WGDC drastically if you do this method. Depending on the size boost pill you use, you may only need 50-70WGDC to see your desired boost up top.
The second way would be to try a Grimmspeed 3port solenoid. I believe the GS 3port has a "bigger" range ie 95% on GS is 30psi, 95% on GM is 24psi. There is a chance Im wrong about the "bigger" range, but I think it will work.
The easiest way would be the boost pill. You can buy a boost pill for like 15-20 bucks shipped. Or you can probably just use the stock one out of the stock boost lines. If it was me, I'd try the boost pill out of the stock lines. Free/cheap and easy. Use the pill by the wastegate, not by the solenoid (The pill by the wastegate has a smaller hole, which will give you more "range", even though the solenoid pill may work fine too).
EDIT: Your #3 idea wont help. Opening up the merge hole in the O2 housing will give you less "creep" ie less boost up top
Oct 22, 2013, 08:53 PM
#30
Unfortunately a 1.6 mm diameter pill in the waste gate line didn't increase the range of control. 98% WGDC is still 24 psi at 7000 RPM and 99% WGDC is still spiking to 29-30 psi at the same RPM. The spike is not as sudden because the pill slows response of the wastegate actuator to changes in WGDC. This actually ends up making it harder to control transient boost and overshoot during the rapid spool up of my Green. A smaller 1.2 mm diameter pill only made the response even more laggy.
I ran some more tests to double check boost on WG spring alone. It seems my earlier results were incorrect. This time I got 19-20 psi across the RPM range, so it looks like I have a weak spring in my 25 lb WGA
I'm going to increase preload on the WGA arm by hacking a couple of millimeters of the end and cutting the thread longer. If that fails to move the WGDC control range down below the 90% mark I'm going to upgrade to the turbosmart WGA which comes with a set of interchangable springs that should make setting baseline boost on spring only a piece of cake.
I ran some more tests to double check boost on WG spring alone. It seems my earlier results were incorrect. This time I got 19-20 psi across the RPM range, so it looks like I have a weak spring in my 25 lb WGA
I'm going to increase preload on the WGA arm by hacking a couple of millimeters of the end and cutting the thread longer. If that fails to move the WGDC control range down below the 90% mark I'm going to upgrade to the turbosmart WGA which comes with a set of interchangable springs that should make setting baseline boost on spring only a piece of cake.