Quote:
Originally Posted by Kingtal0n
It is not necessary, only recommended. The problem is, if the tuner does not know or understand the relationship between air temperature and mass, you may wind up running the engine quite leaner than anticipated on a very cold day- without the OEM air temperature sensor configuration to compensate.
Generally it is used to pull a few %'s of fuel when the air temp gets hot. that means tunes are usually "too rich" for full temperature situations, and the air temp sensor pulls out the fuel to compensate as the air entering the engine begins to heat up.
also, Dont use the Power FC boost control kit, use a stand-alone boost controller such as greddy Type-S or Profec-b.
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I have been running PFC D-Jetro for like 3 years now..........works perfect.
The temperature sensor that comes with the kit is VERY slow response.
I have mine installed in the cold pipe, RIGHT before the throttle body.
IF I drive the car around and don't come to a stop (so as to not allow the engine bay to heat up), the temp sensor always reads roughly equal to the outside air temperature.
Even when I floor it, and go into boost, the temperature sensor does not change. It simply does not react quickly enough.
However, I believe this is a good thing. Due to this effect, I am able to separate out 2 different effects:
1) Effect of "starting air temperature" (i.e. changes in outside air temp.)
2) Effect of "air heating up due to boost" (i.e. air temps going up transiently due to boosting the air).
Since the sensor can only do effect #1, I use the Air Temp vs. Fuel Correction Table to add/remove fuel for cold/hot weather.
I cannot directly detect effect #2, but the effect of the turbo heating up the air should be that at any given boost level/RPM level, the air is heated up a given amount. Under this small assumption, the effect of the turbo heating up the air is taken into account in the main Injection Table via datalogging/tuning of the individual cells.
Again, the net effect is that I use the air sensor reading only to trim fuel as related to changes in the "starting air temperature", i.e. the outdoor air temperature.
i find that it works very very well. You tune the car at temperature X, and then remove some fuel at higher temps and add fuel for lower temps. In practice, this can be done by using known rich values, and then scaling the numbers back to give you what you want.
The hottest temps I see (air temp) are around 35 C, so for all temps above this, I leave the value the same. This way, if the sensor heat soaks in a parking lot on a hot day, it doesn't remove any additional fuel.
If you get into this stuff, one thing that you will become conscious of (which I am) is paying attention to the temperature reading when you start the car up.
If the displayed temperature is higher than about 5-10 C over what you know the outside temp. to be, do NOT beat on the car (obviously depends how aggresive your AFRs are). If your car is tuned with 11.5-12.0 AFRs in high boost, and you boost the car when it is 10C out but the sensor is heatsoaked and reading 30C, you could be in trouble.
Basically, the air temp correction works well, but only as well as the person who is using and observing the unit. For me, my tune is very very safe on the fuel side of things, so I am not too worried about 1-2% differences in fuel. I am not sure how perfectly this works across the whole map (i.e. are the same corrections required at a new temperature needed to keep different parts of the map in check with the reference state at which the enitre map was tuned). If I had a car that was tuned more ambitiously (11.5-12.0 AFRs under boost), I would probably run 2 or 3 different maps entirely..........one for winter, one for spring/fall, and one for summer....just to be safe.
Also, I agree with you on the boost controller. I have the PFC boost control function turned off. I run an AVC-R in tandem. The AVC-R and PFC each have their own dedicated pressure sensor. The two are off by about 0.02 bar, but that is a minor effect, and likely just a minor calibration issue. As long as you tune off of the PFC sensor, it doesn't matter really.