I have the PLX M-300, and I had to do some mods to insure that the laptop recorded the AFRs as seen on the display. On their WEB site they mention how to calibrate to other ECUs but not the PFC. Plus I went one step further then they describe.

The DATALOGIC (DL) has two electrical grounds on it which are only common at the PFC. The cable from the PFC to the DL has an outside shield which goes to the PFC ground but not internally connected to the DL circuit ground. Thus a very small voltage difference is measured between them.

I use the cigarette lighter as a power source for my DL. There is a larger voltage difference betrween it’s ground and the PFC/DL ground.

First I took the DL box apart, and drilled a hole for a ground wire to come out of it. I soldered a wire to the cable grounded shield which comes out the drilled hole to the outside where it then connects to the M-300 power cable ground wire. This step equalizes the ground difference as PLX suggests.

Second I used one of the M-300 supplied noise filtering capacitors. It is connected across the AN1 input (I use this for my wideband) and the DL circuit ground.

PLX then tells you to adjust your logging software parameters such that the logged AFRs match the displayed AFRs on the M-300. That’s fine but you need a constant reading to do this, and at idle my AFRs still jump too much for my liking. I would rather calibrate to an AFR closer to where the unit will actually be used.

This is how I solved this problem. I put the sensor inside a quart jar and covered the top with 4 layers of saran wrap held on and sealed with rubber bands. Then I use my propane torch and filled the jar with propane until the AFR reading went all the way rich. Then using a straw, I slowly blew air inside the jar until a stable AFR of around 11 was on the M-300 meter. Using the laptop and DL, I could look at what they see as opposed to the M-300. The DL was reading lean by about .3AFR. I adjusted the value of C down from 10 until both systems matched. Calibration complete!!!

 

You are the man, great info and great trouble shooting (write up too). This will be very helpful to people. Hell, I would probably need it, although I picked a different WB combo.

 

I see a typo error.

"I use the cigarette lighter as a power source for my DL. There is a larger voltage difference betrween it’s ground and the PFC/DL ground."
The M-300 is connected to the lighter, not the DL.

 

haha, I read that and was like WTF, he must have another mod on his, cuz my datalogit did not need an external ground. Makes since now.

Godd Job Again.

 

i need to find a map to start with for my datalogit. i just put a TO4R on my 7 with twin fuel pumps/ and fuel presure regulator, 3 core intercooler normal stock injectors, full set of Defi gauges, the M-300 wide band. i also put the 3bar map sensor in and changed my setting to option 1 on the commander. i got the PFC boost controler as well but i kinda need some help getting a beggining map so i don't blow my engine while fine tuning. any help with this would be greatly appreciated.