home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > performance & modifications > aftermarket engine management

Reply
 
Thread Tools Display Modes
Old 01-18-2016, 01:08 PM   #76
turbochimp
Board Member
 
Join Date: Nov 2011
Default

Quote:
Originally Posted by bobxyz View Post
It would be great if you could find & post a link to this!
Use of MAP -
MAP is mostly proportional to air flow for a given engine. MAF is absolute airflow (assuming no leaks) but MAP works fine as long as you don't swap engines. So, if MAP is proportional to airflow and AFR is Air per Fuel, then MAP/AFR is proportional to just Fuel. And, when we plot MAP/AFR vs. PW, we end up with a plot of actual Fuel vs. PW. From this, we can extrapolate the line out to the PW that gives zero fuel, which is our desired deadtime.

Is this better, or only more confusing? Sorry if it didn't help....
This helped me tremendously - thank you. It is so much nicer being able to approach something with understanding rather than just following some instructions from somewhere.
turbochimp is offline   Reply With Quote
Old 01-25-2016, 10:11 PM   #77
gross polluter
They see me trollin'
 
gross polluter's Avatar
 
Join Date: Dec 2008
Location: Cold Lake, AB
Default

After spending a few days playing with the MAP/AFR methods on a few cars with known deadtime values, I would not recommend using this method for determining injector opening time. Multiple data collections, implementing a ton of filters to make sure only stable parameters were plotted, and each plot not producing data consistent to show a solid number.

In my professional opinion, using commanded AFR error to dial in the dead time is still the best way to get the most accurate and consistent results.
__________________
'88 245 - 2JZGTE VVTi | MS3X ECU, MS2 TCU | GT3582R-HTA | Staged simultaneous dual fuel | 590whp 580ftlbs

1968 Furd Rustang fastberk | 2JZGTE VVTi | MS3X ECU | PT6776S | 4L80e Microsquirt TCU Sloppy Transbrake | 3.73 8.8" rear end

1981 Piper Cherokee Archer II | All stock
gross polluter is offline   Reply With Quote
Old 01-25-2016, 10:37 PM   #78
turbochimp
Board Member
 
Join Date: Nov 2011
Default

Wow - so are you saying that you couldn't get a linear distribution in any of the tests or that no two tests produced the same line?

I'm not sure if I did this right but here is what I got @ a fairly steady 13.6V:



No idea if this is meaningful or not, but I do feel pretty good about the linear distribution (r2=.888 including obvious outliers). I only did it once - but it corresponds fairly closely to the higher/lower dead time method I did while looking at target overshoot/undershoot in real time.
turbochimp is offline   Reply With Quote
Old 01-25-2016, 11:12 PM   #79
gross polluter
They see me trollin'
 
gross polluter's Avatar
 
Join Date: Dec 2008
Location: Cold Lake, AB
Default

Not one test produced the same line as another. Once you filter out all the junk, you can get results that vary about 200us, which for most knuckleheads on this forum is good enough. However, I make a living calibrating control systems that have to work like stock cars for years on end, so I tend to use and recommend methods that give a much higher degree of precision.
gross polluter is offline   Reply With Quote
Old 01-27-2016, 12:46 AM   #80
bobxyz
Board Member
 
bobxyz's Avatar
 
Join Date: Aug 2014
Location: Boulder, Colorado
Default

So, what are your recommendations for best dead time characterization no holds barred? And for the rest of the TBricks MS crowd?
- graduated cylinders and multiple commanded pulse widths at different voltages?
- vary AFR at idle, or some other target RPM?
- vary MS PW at target RPM?
- use an oscilloscope to measure injector V-I and use the bumps for open/close delay?
- adjust 2squirts vs. 4squirts until equal?
- use your good buddy's V8 TBI settings, and AutoTune it weekly?
- other?

Thanks for your experience and wisdom,
Bob
bobxyz is offline   Reply With Quote
Old 01-27-2016, 01:16 AM   #81
Harlard
Pro Sneaker Peddler
 
Harlard's Avatar
 
Join Date: May 2007
Location: PDX
Default

Quote:
Originally Posted by gross polluter View Post
In my professional opinion, using commanded AFR error to dial in the dead time is still the best way to get the most accurate and consistent results.
Not asking you to spoon-feed me information here, but what is the methodology involved to conduct a commanded AFR error analysis?

Quote:
Originally Posted by turbochimp View Post
Wow - so are you saying that you couldn't get a linear distribution in any of the tests or that no two tests produced the same line?

I'm not sure if I did this right but here is what I got @ a fairly steady 13.6V:



No idea if this is meaningful or not, but I do feel pretty good about the linear distribution (r2=.888 including obvious outliers). I only did it once - but it corresponds fairly closely to the higher/lower dead time method I did while looking at target overshoot/undershoot in real time.
Somewhat of a tangent here; did you manually copy scatterplot values or is there a way to export an MLV scatterplot to xlsx or csv?
__________________


Herr Harlard am Erstens

1979 242 DL

Quote:
Originally Posted by t8fanning View Post
My knob has a big chunk of steel on it

Last edited by Harlard; 01-27-2016 at 06:40 PM..
Harlard is online now   Reply With Quote
Old 01-27-2016, 01:23 AM   #82
turbochimp
Board Member
 
Join Date: Nov 2011
Default

MLV exports under the file menu. I just named the export file with a .xls extension.
turbochimp is offline   Reply With Quote
Old 10-16-2017, 01:41 AM   #83
jsdevel
Board Member
 
jsdevel's Avatar
 
Join Date: Jun 2015
Location: Phoenix, AZ
Default

Here's a link for bosch injector dead times with battery corrections: http://www.e30tech.com/forum/showthread.php?t=103401. Has the green tops listed.
jsdevel is offline   Reply With Quote
Old 10-16-2017, 02:25 AM   #84
gross polluter
They see me trollin'
 
gross polluter's Avatar
 
Join Date: Dec 2008
Location: Cold Lake, AB
Default

Quote:
Originally Posted by jsdevel View Post
Here's a link for bosch injector dead times with battery corrections: http://www.e30tech.com/forum/showthread.php?t=103401. Has the green tops listed.
LOL. That’s data stolen verbatim from one of my other blogs and horribly incorrect.

Do not use anything in that link.
gross polluter is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 09:38 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.