ethorn

as per the discussion in the thread: http://forums.maxima.org/showthread.php?t=321578

I have used my Car-Chip E/X to record intake temperatures. I have just modified to try and record coolant temperature and air flow rate. But here are my current graphs. IDK what the Fuel System status codes mean. Maybe someone with more knowledge than I could help on that one.

TXT file of data http://www.computerinspirations.com/...intaketemp.txt
Excel file of data http://www.computerinspirations.com/...intaketemp.xls

The following graphs should align vertically so you can see the relationship of the data... There are also vertical lines. Those represent hard accell and hard brakeing as it sees it ~.5G.

Air Intake Temp Deg F


Speed in MPH


Fuel in ??? Anyone know?

cobymoby

iTrader: (2)

That's some really good data.

What you are seeing in the third window is when the ECU is monitoring the fuel system in open loop or closed loop.

It is the way the an ECU monitors and adjusts the fuel depending on how much the air/fuel ratio is changing on the car.

Generally during driving that has smaller fluctuations in your modulation of the gas pedal (ie engine load) it will try to operate in closed loop mode as much as possible. During wider fluctuations it will go into open loop.

How hot of a day was it when you ran these tests?

ethorn

You could normalize to the data's opening numbers. The car had sat for just under 9hrs in the shade (car deck). But if memory serves correctly it was around 90, maybe just below. Shortly after I uploaded this I found a graph that was very telling. It was a much shorter trip than this was, so you could see the increase as you sat in the graphs. When I get back home today I will plug in my car-chip and see what the new data says (if it can read it.) I am now monitoring Coolant Temp (since the intake sits above and in front of the radiator) air temp and air flow. I will post a list of everything the Car-Chip is supposed to monitor, but If memory serves me correctly AirFlow isn't readable on the MAX... But again.... I will find out tonight.

What exactly is the difference between open and closed loop? And why are there 2 graphs of it?

ethorn

most of that driving was on asphalt.. and it was sunny and mostly clear. So the temp near the road would be higher than the ambient.

ethorn

Here is my trip home today... It rained for the first half and according to the Outside temp on the car it was 81 at that time. When it stopped raining (well I outran the rain :-) ) The outside temp went up to 92 for the second half. The car had been driven for about half an hour about 1.5 hrs before this trip started.

http://www.computerinspirations.com/.../airintake.txt -- Plain TXT file
http://www.computerinspirations.com/.../airintake.xls -- Excel 2003 with graph

ethorn

Coby.... any idea what lbm/s is?

cobymoby

iTrader: (2)

lbm/s is the value that the MAF sensor calulates for the air that is passing though it. It stands for "pounds mass per second". The mass being the weight of the air in pounds per second of data sample. By looking at the data though it only reads the air in an "a little/a lot" type manner. There are only three data points 0.0, 0.1, 0.2.

There are two graphs for the open loop closed loop because it is reading the front bank and the rear bank of cylinders. The front three cylinders have their own two O2 sensors and the rear three have their own two O2 sensors. The ECU looks like it is monitoring the two banks on their own open/closed loop monitoring for the A/F.

ethorn

ok... cool. Here are the other parameters it can monitor if the car supports it:

Vehicle speed - Always monitored 5sec interval
Engine Speed - This and the rest are monitored in 5, 10,20,30, or 60 sec intervals. Choose any 4 from here down to monitor per trip.
Throttle Position
Coolant temperature
Engine Load
Intake Manifold Pressure
Air Flow Rate
Intake Air Temp
Timing Advance
Fuel Pressure
Fuel System Status
Short Term Fuel Trim (B1)
Short Term Fuel Trim (B2)
Long Term Fuel Trim (B1)
Long Term Fuel Trim (B2)
O2 Sensor Voltage (B1, S1)
O2 Sensor Voltage (B1, S2)
O2 Sensor Voltage (B1, S3)
O2 Sensor Voltage (B1, S4)
O2 Sensor Voltage (B2, S1)
O2 Sensor Voltage (B2, S2)
O2 Sensor Voltage (B2, S3)
O2 Sensor Voltage (B2, S4)
Battery Voltage