Boost controller on a nDBW T-28
06-10-2004, 11:30 AM
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Boost controller on a nDBW T-28
I finally have worked out most of my little gremlins and I must say the car runs great. I needed a new MAF and found yet some more leaks. Now it pulls real hard most of the time, but I am noticing that sometimes I don't hit full boost and other times I do but boost tapers off toward redline. I don't know why it does this and need some suggestions on how to track this down. It seems like ECU limiting boost and I am thinking that I will not be able to change this behavior...
I am starting to think about just getting an EBC to get consistent boost. I know the DBW guys run these, is there any reasons for us nDBW guys not to use them? I do not want to raise or lower my boost, just keep the boost where it should be throughout the rpm range. Any thoughts?
TIA - Rob.
I am starting to think about just getting an EBC to get consistent boost. I know the DBW guys run these, is there any reasons for us nDBW guys not to use them? I do not want to raise or lower my boost, just keep the boost where it should be throughout the rpm range. Any thoughts?
TIA - Rob.
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06-11-2004, 09:09 AM
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I heard others had the same exact problem, so I never looked into it further.....
I'm not too concerned with it right now since I can't run more than 19psi without the engine bucking at 3500 RPM
06-11-2004, 09:38 AM
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Engine load = MAF/RPM
more airflow per RPM = more load
less airflow per RPM = less load
with the high-flow cat, I would expect a higher load, so the ECU is probably lowering the boost to drop the load a little.
less airflow per RPM = less load
with the high-flow cat, I would expect a higher load, so the ECU is probably lowering the boost to drop the load a little.
06-11-2004, 10:25 AM
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Wow, interesting. Reading Bentley I think I understand
Is it true that the Current load is MAF/RPMs, and specified load is programmed on the chip?
If that is true - Bentley says that boost is considered too high if the current load is higher that the specified load. The ECU should decrease the duty cycle of the N75 (I think means open the N75 valve letting more boost go to the wastegate thereby opening it). It says if the duty cycle is close to 0% in this situation, there is a problem - meaning the ECU tried to lower boost by letting nearly all the pressure to the wastegate, but could not lower the boost.
My bet is that my loads are withing the 3ms max deviation, but my duty cycle is high when my boost falls off. I guess that I will be able to see if my N75 opens up and at least then prove the ECU told it to.
I am gonna log block 114 and see whats going on...
So if this is in fact the problem then I have to either get GIAC to change my chip (uh, yeah) or go with a EBC, right?
If that is true - Bentley says that boost is considered too high if the current load is higher that the specified load. The ECU should decrease the duty cycle of the N75 (I think means open the N75 valve letting more boost go to the wastegate thereby opening it). It says if the duty cycle is close to 0% in this situation, there is a problem - meaning the ECU tried to lower boost by letting nearly all the pressure to the wastegate, but could not lower the boost.
My bet is that my loads are withing the 3ms max deviation, but my duty cycle is high when my boost falls off. I guess that I will be able to see if my N75 opens up and at least then prove the ECU told it to.
I am gonna log block 114 and see whats going on...
So if this is in fact the problem then I have to either get GIAC to change my chip (uh, yeah) or go with a EBC, right?