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How accurate is power fc boost display
HOW ACCURATE IS POWER FC BOOST DISPLAY ON COMMANDER?
IF I READ 0.9 BAR ON COMMANDER DISPLAY , HOW MUCH SHOULD IT REALLY BE?: 0.93? 0.95?:scratch: I KNOW PFC COMMANDER READ LOWER BOOST, BUT SINCE I WON'T HAVE A LOT OF GAUGE , it will be interresant to know difference between commander display and real boost gauge to do my "self adjust" |
It should say 0.xx not 0.x. And if you put it in hold mode. It only shows peak boost. Is anything you should just have a gauge
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My Power FC was within one tenth psi of my boost controller. So in other words dead on.
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Originally Posted by montego
(Post 9559996)
My Power FC was within one tenth psi of my boost controller. So in other words dead on.
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Bar is not the same as psi.
And the PFC reports boost in kg/cm2, which is not the same as bars either (though is close). The stock PFC boost calibration is inaccurate and it tends to underreport boost as boost increases. Search on the PFC board for many threads on calibrating it. |
Originally Posted by moconnor
(Post 9560012)
Bar is not the same as psi.
And the PFC reports boost in kg/cm2, which is not the same as bars either (though is close). The stock PFC boost calibration is inaccurate and it tends to underreport boost as boost increases. Search on the PFC board for many threads on calibrating it. SORRY FOR CONFUSION SO, 0.9 BAR WILL BE 0.907 BAR ( 0.91 BAR )...:scratch: |
What people are saying is if you want it to be realy accurate you would need to calibrate your map sensor to your PFC as Apexi did not do it perfect and not all map sensors will show the exact same voltage.
1 bar=14.5psi 1kg/ccm2=14.2psi Do you use bar in Germany? |
Originally Posted by MILOS7
(Post 9560003)
so 0.9 bar will be 1 BAR !!??
This is what I did: Went out for a several 4th gear pulls on high and low boost settings. As I did that I checked my greedy profec b (in psi), and PFC (in kg/cm2) . I wrote the values down and then went home and did the conversion from kg/cm2 to psi. Each time the PFC was within a tenth pfc a psi from the greddy unit (not a tenth of bar). Honestly it really does not matter what boost you are at given that you have a TUNED PFC. At this point the boost reading is just a reference now. Meaning that you have enough fuel for whatever boost the PFC reads. |
The boost reading is only as accurate the scaling of the sensor. That's with any pressure sensor on any device. The Power FC does not adjust for changes in altitude/barometric pressure like the factory ECU does. So there will be some small variation as the weather changes.
As far as accuracy or usefulness, the Power FC is the only boost gauge in my car. I have my GM 3 bar sensor calibrated well enough that I trust it as much or more than any other gauge. I put the Commander in 1 or 2 channel monitor mode (typically boost and water temp) and read boost off of there as I drive, using the peak hold mode to see peak boost. Since I control boost with the Power FC directly, I don't have to deal with discrepancies between gauges at all. All my fuel, spark, and boost control tuning are based on a consistent single reading, and my overboost fuel cut will occur around 17psi on the PFC, a little less than 1.25 kg/cm^2. |
Yesterday I've found my PFC Commander boost is not syncing up with my analog gauge. Yesterday I did a couple of pulls with the new setup and the analog gauge was reading 14 psi. The commander was showing peek of only 0.85 kg/mm^2. This is very worrisome. If the ECU thinks boost is lower than it is, than it will not send sufficient fuel. For reference, the boost was set to 1.00 kg/mm2.
To troubleshoot, Sandro helped check the calibration on my map sensor and analog gauge. The gauge reading match the sources reading, so it was OK. When pressurized, the map sensor was giving voltage readings that corresponded to that of other map sensors Sandro had on hand, so it was OK. If the map sensor is good, than the problem must lie in the wiring, ecu or the commander itself (right?). Sandro recommends we check the PIM measurements (with a dataloggit - I don't have one) to make sure the ecu is seeming the correct boost and sending fuel/timing accordingly. Hopefully the problem is in the commander (although I doubt it). If anyone has any ideas/suggestions as to what could be the culprit, please post your thoughts. |
Thats normal. Its documented that the pfc reads lower than actual boost. In chucks tuning notes there is instructions on how to recalibrate it. Mine reads around .59 kg/mm2 when my analog gauge reads 10psi.
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That would be all well and good if it was always like that (since I was tuned). However, when I was tuned, it used to read out 1.00 kg/mm^2 peak and match the analog. If it now reads less and has not been retuned, that is worrisome.
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Originally Posted by arghx
(Post 9560377)
The boost reading is only as accurate the scaling of the sensor. That's with any pressure sensor on any device. The Power FC does not adjust for changes in altitude/barometric pressure like the factory ECU does. So there will be some small variation as the weather changes.
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Originally Posted by GoodfellaFD3S
(Post 9820386)
This^^ :)
If the ECU is tuned given one atmospheric condition, and we clearly drive in many varying conditions, how do we protect our motors from these changes? What would be considered sufficient fuel at 12 psi would certainly be lean if the same fuel was used at 14 psi. Does the Pressure In Manifold (PIM) reading in the ECU read from something other than the map sensor? EDIT: For reference, barometric pressure yesterday during my pulls was 29.93" and ambient temperature was 43*F. |
Found this post:
Originally Posted by cymrex
(Post 161668)
I believe what you are seeing is related to altitude and the lack of an atmospheric pressure sensor in the PFC. Check page f22 and f34 of the workshop manual and you will notice the stock ecu contains an integral Atmospheric Pressure Sensor. The MAP sensor stands for Manifold Absolute Pressure. The MAP sensor gives the absolute pressure uncorrected for current atmosheric pressure. Thus MAP references zero mmHG. The boost guage references current atmosheric pressure as zero. Thus the boost gauge and the MAP output will differ. Remember atmosheric pressure varies so the correction factor is not a set amount. High and low pressure weather systems directly change the correction factor between absolute pressure and boost referenced to atmospheric pressure. The stock ECU uses the integral Atmosheric Pressure Sensor as another input reference. I could find nothing on how the atmosheric pressure sensor data is used by the ECU, but it was there for a reason. The PFC must be showing the MAP sensor output. This should not harm the engine because absolute pressure and intake temperature are used to calculate how much true oxygen is in the intake charge thus the right amount of fuel will be added to get the desired ratio. The atmoshere is a relatively homogeneous mixture so there are fewer molecules overall in a cubic centimeter of atmoshere at altitude still contains the same percentage of oxygen. A MAP sensor with the intake temperature is the correct tool to figure out how much oxygen is in the intake charge. So if you get the Air Fuel ratios right then everything will be OK. At altitude you will never reach the higher absolute pressure parts of the PFC settings.
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Well, right. You have to make sure you're tuned for the higher boost level shown on the commander and your car should be safe.
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Yeah. Its tuned for the 1.00 kg/mm^2.
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Originally Posted by s1mpsons
(Post 9820270)
Yesterday I've found my PFC Commander boost is not syncing up with my analog gauge. Yesterday I did a couple of pulls with the new setup and the analog gauge was reading 14 psi. The commander was showing peek of only 0.85 kg/mm^2. This is very worrisome. If the ECU thinks boost is lower than it is, than it will not send sufficient fuel. For reference, the boost was set to 1.00 kg/mm2.
To troubleshoot, Sandro helped check the calibration on my map sensor and analog gauge. The gauge reading match the sources reading, so it was OK. When pressurized, the map sensor was giving voltage readings that corresponded to that of other map sensors Sandro had on hand, so it was OK. If the map sensor is good, than the problem must lie in the wiring, ecu or the commander itself (right?). Sandro recommends we check the PIM measurements (with a dataloggit - I don't have one) to make sure the ecu is seeming the correct boost and sending fuel/timing accordingly. Hopefully the problem is in the commander (although I doubt it). If anyone has any ideas/suggestions as to what could be the culprit, please post your thoughts. I am wondering if it could be stock map sensor on the way out? How did you fix your problem? I too am concerned about being lean as power FC doesn't read boost accurately? Thanks |
Use your commander to actually see which fuel rows it is in when the non PFC boost gauges read 14 psi. Then you can determine if it is only the PFC displayed boost is wrong or the PFC is also using a wrong lower boost value.
You could also check the MAP sensor hose for leaks or maybe an oil plugged up map sensor filter. |
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