Not to beat the MBC issue to death but I have found something very interesting....
02-15-2004, 12:46 PM
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Not to beat the MBC issue to death but I have found something very interesting....
First off I have STFA's and some of the material is dated. Lots of myths and good facts. This one piece of info has got me thinking a lot.
Looking at the last time I dynoed at AMS (Sept 2003) I noticed the boost tapered from a peak of 1.25 bar at 3,000 to 5,000 RPMs to a low of 1 bar at 6,800 - 7,000 RPMs. This occured on the APR stage3 software, 100 oct program but not on the AMS stage 6 (it was designed for the hardware I have and the APR is not). I have checked for boost leaks and there are none. Is it possible that due to the extra hardware I have I am satisfying the ECU's request for torque without all the boost? Could be the reason my trap speeds are about the same as a standard APR stage 3.
Paging Jason, Troy or Tory to help setup an MBC for my car. I have the hardware needed I just don't feel good about doing it without some log expert helping to ensure the EGT's and injector duty cycles are correct. I also wonder what the target boost levels should be?
Thanks in advance!<ul><li><a href="https://forums.audiworld.com/s4/msgs/1101228.phtml">https://forums.audiworld.com/s4/msgs/1101228.phtml</a</li></ul>
Looking at the last time I dynoed at AMS (Sept 2003) I noticed the boost tapered from a peak of 1.25 bar at 3,000 to 5,000 RPMs to a low of 1 bar at 6,800 - 7,000 RPMs. This occured on the APR stage3 software, 100 oct program but not on the AMS stage 6 (it was designed for the hardware I have and the APR is not). I have checked for boost leaks and there are none. Is it possible that due to the extra hardware I have I am satisfying the ECU's request for torque without all the boost? Could be the reason my trap speeds are about the same as a standard APR stage 3.
Paging Jason, Troy or Tory to help setup an MBC for my car. I have the hardware needed I just don't feel good about doing it without some log expert helping to ensure the EGT's and injector duty cycles are correct. I also wonder what the target boost levels should be?
Thanks in advance!<ul><li><a href="https://forums.audiworld.com/s4/msgs/1101228.phtml">https://forums.audiworld.com/s4/msgs/1101228.phtml</a</li></ul>
02-15-2004, 01:06 PM
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I'd think the 1.2B range would be ideal provided timing and other variables
are optimized for this. I don't get the use of the MBC on this car if it starts at 1.25B and tapers to 1B as rpms rise... seems unnecessary. MBCs on our cars seem to be used to fix a code issue or poorly matched solution where the ECU cannot control operational variables out of its range of programming.
What does the AMS code do boost wise?
What does the AMS code do boost wise?
02-15-2004, 01:26 PM
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AMS boost is flat from about 3,000 - 3,500 to redline the APR is not...
Looking at R1 eaters boost line posted last week got me thinking (see attached link). He maintains full boost to redline and I do not. I also have lots of extra goodies that help airflow. Based on the link (in my first post) maybe I am not getting the most out of my hardware because the ECU is cutting boost once satisfied with airflow as measured by the MAF to achive requested torque levels.
I wonder if unplugging the MAF would allow boost to stay in up to redline?<ul><li><a href="https://forums.audiworld.com/s4/msgs/1511404.phtml">https://forums.audiworld.com/s4/msgs/1511404.phtml</a</li></ul>
I wonder if unplugging the MAF would allow boost to stay in up to redline?<ul><li><a href="https://forums.audiworld.com/s4/msgs/1511404.phtml">https://forums.audiworld.com/s4/msgs/1511404.phtml</a</li></ul>
02-15-2004, 01:57 PM
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Interesting. I think you're definitely on to something with this. In Mike's
experience with APR software though you're going to throttle cut using an mbc. If you still want to try I'd set it at 1.2bar and go from there. Try to keep the egts similar at first and watch the timing/throttle. Then start moving it around to watch airflow/timing behavior to get a feel for which way to go. Then dyno, or have a consistent test method(3rd gear say 3000-7000rpm and time it) to see what the power's doing.
I wonder how the different tuners use the torque target? APR seems to use boost values, ie on K03 programming the boost is still controlled with K04s to withing say 10-15% of a given g/s maf reading. The Xchip goes whacko on boost with K04s necessitating the mbc, so its not controlling the boost by the same parameters. So what is it controlling with, or is it even using a given(attainable) torque target? Maybe it just sets some superhigh value and lets the car give it all its got until some safety is tripped?
Anyway, who knows? Just try it!
I wonder how the different tuners use the torque target? APR seems to use boost values, ie on K03 programming the boost is still controlled with K04s to withing say 10-15% of a given g/s maf reading. The Xchip goes whacko on boost with K04s necessitating the mbc, so its not controlling the boost by the same parameters. So what is it controlling with, or is it even using a given(attainable) torque target? Maybe it just sets some superhigh value and lets the car give it all its got until some safety is tripped?
Anyway, who knows? Just try it!
