[Diy_efi] Capture advice

[Tim Marsteiner]

I have been logging some data on a big V-Twin normally
aspirated air cooled motorcycle. It is an alpha-n
based EFI system. (max RPMs of 6000)

The EGT sensor is exactly 3" from the cylinder head
and the wideband O2 sensor is exactly 12" from the
cylinder head.

I have written some perl scripts to process the data
and was wondering what the delays in the EGT and O2
readings will be?

Also, the wideband O2 is the DIY NTK setup. Any idea
of an O2 voltage correction scheme based on EGT?

The PDA logging code is code I've written so I can
change the order and/or add delays when capturing.

The current code loop is as follows:

Initiate EGT reading (using a capture card, it takes
70 ms to prepare result)
Read RPM
Read Throttle Position (TI AREA, max is 1040 mm2)
Read APS (air per stroke, this isn't really required)
Read EGT result
Read O2 Voltage
Every 20th loop capture either Air Temp, Eng Temp or
Barometric pressure


As you can see from the log below each loop takes a
little over 100 ms.(I've added another bit of time
resolution but don't have any logs with it yet).

Any comments or guidence is appreciated.


BTW I am pretty sure that peak EGT occurs at an A/F of
14.7:1 on this engine. I am going to build up an
adjustable narrow band simulator which will allow me
to dial in closed loop A/F to verify this. I'll post
the results.


Thanks,
Tim


Here is a short data log sample:

  TIME  TI AREA  RPM O2VOLT ENGTMP AIRTMP EGT2 
------- ------- ---- ------ ------ ------ ---- 

18:11.5  10.03  2633  3.247  249     91   1292
18:11.7  10.28  2607  2.505  249     91   1293
18:11.8  21.69  2602  2.364  249     91   1294
18:11.9  76.88  2799  2.715  249     91   1296
18:12.1 227.03  2670  2.549  249     91   1297
18:12.2 377.50  2679  2.193  249     91   1300
18:12.4 425.28  2708  2.007  249     91   1301
18:12.5 427.66  2789  2.066  249     91   1303
18:12.7 421.72  2817  2.129  249     91   1304
18:12.8 411.56  2827  2.222  249     91   1307
18:12.9 391.44  2895  2.295  249     91   1309


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