are you targeting less bosst control % towards 100% tps?
FAST XFI BOOST Control finally some results!!
- Thread starter norbs
- Start date
are you targeting less bosst control % towards 100% tps?
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Let me know how the 4 port works out. Was looking over the schematic again but to chicken to try it.
Edit: My concern would be that you may posibley double the range but it may respond really slow when slewing from max DC%.
Allan G.
No, but that might be a good idea since it tends to creep at wot, I really think it would be best to wait for the 4 port solenoid, we are running out of control with this lower port not being connected.
I would not be chicken I have a feeling its going to work well and provide a good balanced control, actually its going to be more sensitive to tune than before. As soon as it comes in I will get logs up. The key is not to have the DC at extreme high or low, this is where I am finding you "lose control", I would say 20-90% is the max range.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
This would be difficult when using PA Boost control. In this mode, TPS and min KPA tables are not enabled. Boost DC will start at 100% while on the T-brake building boost and slew to whatever value when launching and may not keep up. This may be a trouble area.
Keep the PA boost table in mind when tuning the normal tables. This is important for time-based control at the track.
Allan G.
This is true, I wish we could have that 100% target changed in the software.
I must not be following what you guys are saying. Do you have the PA Hold wired to the trans brake? If so, set your PA Enable values so they will come in while on the trans brake, then set the Boost DC% to your launch boost at the timer value of zero? I must be missing what you are trying to do.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Cal,
Yes, I'm using the PA hold. When the t-brake is released, it starts the counter.
With that being said, when using manifold pressure as a reference, the boost DC% starts at 100%. Even if I target 20% boost control because there is no pressure sensed on the transducer. When Boost starts to build, it will try and reach the target WG pressure at "0" seconds. In my case, WG DC is still moving around in this area since I'm trying to leave hard and boost builds slowly. After launch, it hits an area where the boost builds quikly and may overshoot. Using boost as a reference signal can be tricky and force the controls to react differently than having constant CO2
Of course, having instant CO2 would help.
Min Map KPA and TPS boost settings are not applicable on PA Boost control but using PA enable RPM seems work in a similar way to Min Map.
Allan G.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Just to add to the above,
When using manifold reference, there is a self induced time lag to respond. The controls start at 100% DC and reduce to 80% with very little effect. What Norbs was eluding to would be to have the operating window of DC% as a user defined value, maybe 80%-0% for example to quicken the response.
Allan G.
I am not sure I understand what you guys are wanting. The duty cycle is so high because you aren't reaching your Target WG pressure yet. If we forced it lower, it would take even longer to reach the Target. It may be easier to call me so I can understand exactly what you are wanting and perhaps get you a solution.
I think it would more then "help"
I think it would more then "help"
That is correct, just want to have a user defined max duty cycle starting point at a min kpa limit, then it will be allowed to go to 100% if needed.
Why is the XFI boost control such a PITA to set up ?
Pre XFI I was running a Translator pro & the closed loop boost control was super easy to set up & functioned perfectly.
For 4 times the cost you would think FAST would be able to build in a usefull & simple controler ?
Pre XFI I was running a Translator pro & the closed loop boost control was super easy to set up & functioned perfectly.
For 4 times the cost you would think FAST would be able to build in a usefull & simple controler ?
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
It is not a complete PITA to set up. Fast has designed this feature to work as a universal system and make it flexable to use any solenoid you want to use.
Using manifold pressure as the WG control pressure can be tricky. Doing this has some drawbacks and makes it harder to control boost over using CO2.
I never owned an AMS500 or 1000 but looking at the schematic, I'm assuming the reasoning behind the two solenoids is CO2 conservation. Once the WG is pressurized in a two solenoid set-up, it only needs to add CO2 to make up for any leakage and consuming very little CO2. If this is truly how it works, than it is a clever strategy.
In the Fast one solenoid set-up, the solenoid is cycling continuously (when controling boost) and consuming CO2(or manifold pressure) by exhausting to atmosphere. Not ever using CO2, I don't know how frequent a bottle would need to be changed. I'm also guessing that regulating CO2 near the max control pressure would help. This may ultimatly be the direction I will be taking.
Allan G.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Cal,
My opinion is the issues revolve around using manifold pressure. It forces the controls to chase the target and react since control pressure is not available until it builds boost. It appears that you can't make it respond fast enough through PID settings to get the perfect control. I think that what I have is acceptable with about a 2-3 PSI varience but my PID values are much different than Norbs (100,60,25).
Allan G.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Just an update on this sensor and installed location. I was driving my car this weekend to and from a local cruisnight. I noticed I didn't here the solenoid cycling when coming off idle. The solenoid is mounted to the firewall is is very noticable when it cycles. I started troubleshooting the system and found that the solenoid was on at 100% of the time. I looked deeper and saw that the analog 8 pressure sensor was reading -25 psi. apparently the Wastgate gets a little hooter than the sensor can handle. When the sensor failed, the solenoid defaulted to 100% open.
This could have been disasterous on a car with CO2 or if the spring is very heavy. I was only driving normally so didn;t hurt anything but this would have overboosted for sure on most peoples cars that run smaller turbos or wastegates.
My fix will be to insulate the sensor with a short piece of 4 AN line. For anyone mounting the sensor, please be aware of the amount of heat that it will see.
Allan G.
