Advantages of GM solenoid over MBC?
Jul 11, 2007, 08:54 AM
#31
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the stock ECU's knock detection is the safe guard. when it detects significant knock, it pulls timing immediately. If knock continues it begins to run on the low octane fuel and timing maps. There are also boost limit values based on RPM that will cut boost/fuel when exceeded.
There is a "limp" mode on the stock setup, but I don't think it's known exactly how it works. There are multiple boost and WGDC maps, but everyone seems to get irregular results from changing only one of them. Some people are running on map 2, some on maps 2 and 3, some on 3 alone. So, if we could figure out which maps run in exactly which circumstances we could utilize the stock "limp" mode as overboost protection.
There is a "limp" mode on the stock setup, but I don't think it's known exactly how it works. There are multiple boost and WGDC maps, but everyone seems to get irregular results from changing only one of them. Some people are running on map 2, some on maps 2 and 3, some on 3 alone. So, if we could figure out which maps run in exactly which circumstances we could utilize the stock "limp" mode as overboost protection.
Jul 11, 2007, 09:07 AM
#32
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As a follow up. A MBC has no idea what pressure you are running it just regulates a rate of air flow that you set. Is the ECU smarter than that? Does it know what boost you are running? I want to know, can you set it for 21psi and have it hold 21psi no matter what temperature, conditions etc... or is like setting fuel flow in that the computer has no idea what your a/f ratio is? Would an electronic boost controller like AEM's trueboost be able to do this, that is, you set boost for a number (21psi) and it will hold 21psi no matter what? Thanks in advance.
Jul 11, 2007, 09:51 AM
#33
For example, I run around 23.5 psi at 250% load. That's the value that this table works from.
WGDC is wastegate duty cycle. This value is actually a measure of the duty cycle of the boost control solenoid and not that actual wastegate.
Jul 11, 2007, 09:57 AM
#34
As a follow up. A MBC has no idea what pressure you are running it just regulates a rate of air flow that you set. Is the ECU smarter than that? Does it know what boost you are running? I want to know, can you set it for 21psi and have it hold 21psi no matter what temperature, conditions etc... or is like setting fuel flow in that the computer has no idea what your a/f ratio is? Would an electronic boost controller like AEM's trueboost be able to do this, that is, you set boost for a number (21psi) and it will hold 21psi no matter what? Thanks in advance.
Actually, the ECU doesn't know what your AFR is in open loop operation. It knows how much fuel is requested at a give load and RPM as well as airflow, but not necessarily AFR. This means it cannot actually make adjustments, or "trim" the fuel in open loop to reach a desired AFR. The AFR depends on the fuel map which is set by the tuner.
Aug 23, 2007, 08:45 PM
#35
A simple mod to combat the infamous boost creep of the FP 18lbs actuator
Before: FP green on pump with Dejon Tool MBC & 18lbs actuator...
After: Same conditions as above but with the Greddy Profec B Spec-II EBC instead of the MBC
You be the judge
Before: FP green on pump with Dejon Tool MBC & 18lbs actuator...
After: Same conditions as above but with the Greddy Profec B Spec-II EBC instead of the MBC
You be the judge
Aug 23, 2007, 09:16 PM
#39
Did some logs on the dyno today as I will be putting a Forge High Boost actuator on my FPgreen soon.
Here is a 3rd gear pull on the dyno with a FPgreen with a stock Evo 9 actuator and a GM boost solenoid:
23.8 PSI @ 7,000 rpm (WGDC @ 100% maxed out):
22.2 PSI @ 7600 rpm:
1st through 4th log on the street a month or so back, 24.4 psi in 4th @ 7200 rpm:
Mods in sig. I am hoping the Forge actuator holds more boost.
Here is a 3rd gear pull on the dyno with a FPgreen with a stock Evo 9 actuator and a GM boost solenoid:
23.8 PSI @ 7,000 rpm (WGDC @ 100% maxed out):
22.2 PSI @ 7600 rpm:
1st through 4th log on the street a month or so back, 24.4 psi in 4th @ 7200 rpm:
Mods in sig. I am hoping the Forge actuator holds more boost.
Last edited by razorlab; Aug 23, 2007 at 09:28 PM.
Aug 23, 2007, 09:20 PM
#41
The AVC-R does work well but costs more than $400 more than a GM solenoid. I've also seen a couple bad AVC-R units in the past year. They used to be solid units. Not sure what happened. When they work, they work great though.
While we are on EBC's. The blitz SBC works very well too. However it doesn't have RPM based boost control
Aug 23, 2007, 10:14 PM
#43
Razorlab -- What fuel are you running when holding 23psi + at 7K+ rpm? Also any idea where the stock 9 maxes out and starts just blowing hot air (peak psi and redline)? Thanks
PS -- For those looking to run Meth / Alk safely you really should incorporate a failsafe (that can kill boost) if certain conditions occur(e.g. Zeitronix ). The ECU will not be able to react quick enough if you have a meth pump failure / clogged nozzle / etc and your engine will likely blow...But then you will have a great excuse to build a monster...
PS -- For those looking to run Meth / Alk safely you really should incorporate a failsafe (that can kill boost) if certain conditions occur(e.g. Zeitronix ). The ECU will not be able to react quick enough if you have a meth pump failure / clogged nozzle / etc and your engine will likely blow...But then you will have a great excuse to build a monster...
Last edited by cij911; Aug 23, 2007 at 10:17 PM.
Aug 24, 2007, 06:36 AM
#45
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the stock ECU's knock detection is the safe guard. when it detects significant knock, it pulls timing immediately. If knock continues it begins to run on the low octane fuel and timing maps. There are also boost limit values based on RPM that will cut boost/fuel when exceeded.
There is a "limp" mode on the stock setup, but I don't think it's known exactly how it works. There are multiple boost and WGDC maps, but everyone seems to get irregular results from changing only one of them. Some people are running on map 2, some on maps 2 and 3, some on 3 alone. So, if we could figure out which maps run in exactly which circumstances we could utilize the stock "limp" mode as overboost protection.
There is a "limp" mode on the stock setup, but I don't think it's known exactly how it works. There are multiple boost and WGDC maps, but everyone seems to get irregular results from changing only one of them. Some people are running on map 2, some on maps 2 and 3, some on 3 alone. So, if we could figure out which maps run in exactly which circumstances we could utilize the stock "limp" mode as overboost protection.
There is one way you can accomodate this, is to do what I did. I figured out what the difference was between the maps (The actual numbers) percentage wise. The highest number map, I believe map No. 2 on my 05 0011 ROM is the one I am putting my primary map numbers into, then using the percentage difference I calculated between teh maps, I adjust the numbers by that percentage, then input the numbers into Maps 1 & 3. Basically, I am just replicating the way the stock maps are set-up as I figure they *hopefully* knew what they were doing when they set it up that way.
The only time all three of my maps are the same is when I am tuning them, then with 5 more minutes of work, Maps 1 & 3 are different (Slightly) than Map 2. I am waiting for my JDM MAP sensor to get here to see really well what all the changes I am doing are actually doing.. He he...