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View Full Version : Why is lbs/min maxed at 86.69 in datalog?


Redline Motorsports
January 21st, 2011, 11:32 AM
2010 E38 car with the loooonngggg MAF table. The datalog stops at 86.68 lbs/min if the max grams/sec is approx 1800 then lbs/min should read to 238!

Is this just a EFI pid that needs to be increased? The project I am working on should be closer to 100 lbs/min....

Howard
Blacky
January 21st, 2011, 04:01 PM
Hi Howard,
What is the exact name of the PID?
Paul
Redline Motorsports
January 21st, 2011, 04:03 PM
Its SAE.MAF
Redline Motorsports
January 22nd, 2011, 06:34 AM
Any answer to this?????? I need data!!!!!!!!!

Tried to look through the sae generic folder and can't see where a limit is set....
Blacky
January 22nd, 2011, 07:56 AM
Can you send a log file with the PID logged and pegged at its maxed value?
Regards
Paul
Redline Motorsports
January 22nd, 2011, 10:24 AM
you got mail....
Blacky
January 22nd, 2011, 10:57 AM
Thanks Howard,

The SAE.MAP PID is maxed out.
The MAF cannot process or display values higher than 655.35 grams/second (which is 86.69 lbs/minute). That's just the way the SAE have defined that PID.
GM.MAF (aka MAF_GM in V8) is worse, it tops out at 511

Regards
Paul
Redline Motorsports
January 22nd, 2011, 04:40 PM
What do you think GM's rational was in providing a MAF that can read to 1800+ grams/sec and not be able to report that MAF's range?
Blacky
January 22nd, 2011, 05:16 PM
I can't guess at GM's rationale, since that PID is not defined nor controlled by GM. That PID is defined by the SAE, probably in consultation with CARB, EPA or any number of other standards bodies.
Have you tried logging GM's MAF PID: GM.AIRPERSEC? That seems ot have an upper limit of over 2000 g/s. I'd be interested to see if it also stops at some artificial limit.

Regards
Paul
Redline Motorsports
January 23rd, 2011, 07:46 AM
Logged GM.AIRPERSPEC.....

Reported 801.88 grams/sec or 106 lbs/min!

Now I will make a calculated PID to reverse it! Good call Paul!

Thanks

HT
Blacky
January 23rd, 2011, 08:47 AM
Hi Howard,

I'll email you an updated gm_enhanced.prn with lbs/minute configured for that PID.
Also the default grams/second range was set at only 0..10, I've changed that to 0..1000

Regards
Paul
Doc
January 24th, 2011, 04:54 AM
Paul could you cc me on this please. Thanks.
Blacky
January 24th, 2011, 11:29 AM
The updates I sent Howard are included in this pre-release:
http://forum.efilive.com/showthread.php?15395-January-24th-2011-pre-release

Regards
Paul