Open Loop Boost - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MSPNP MSPNP specific Megasquirt related discussion.

Reply
 
 
 
LinkBack Thread Tools
Old 11-29-2012, 11:26 PM   #1
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default Open Loop Boost

I know i need to get my closed loop tuned, just dont have the time right now. I have open loop working pretty well, i was curious if any has seen it where on the same drive, it seems perfect (in my case, builds quick to 13ish and holds throughout), then about 5 miles later it drops to about 10psi and holds there. I have looked at my datalogs, and ambient temps are similar. AFR's are similar. Boost duty is identical. RPM range and TP are almost the same, but for some reason at the same rpm and boost duty i am making different pressures.

I know that open loop is kinda quirky, and i should get over to closed loop. But whats up with the inconsistency?
wolfram is offline   Reply With Quote
Old 11-29-2012, 11:32 PM   #2
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default

Here are my examples....
Attached Thumbnails
Open Loop Boost-boost1.jpg   Open Loop Boost-boost2.jpg  
wolfram is offline   Reply With Quote
Old 11-29-2012, 11:34 PM   #3
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default

Also, i live at about 5500 ft in Denver, if that helps any.
wolfram is offline   Reply With Quote
Old 11-29-2012, 11:36 PM   #4
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

It should take no more than 10-minutes to tune closed-loop.
hustler is offline   Reply With Quote
Old 11-29-2012, 11:46 PM   #5
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default

I know, but i think i am closed loop challenged. I read a few really good posts on here a month or so ago, and had all kinds of problems with over shoot and so forth. But then again, i think i had something inherently wrong as at the same time i couldn't even get the open loop to work. Maybe i just suck it up and get back on the saddle. I was so happy that i got it to work well in open loop, then the inconsistancy ruined it all!

Plus in Denver we have 70deg days that follow a 10deg day, so i think open loop may be a bad idea anyway. Not to mention the 5000ft gradient i deal with on a frequent basis.

Just so i get this right, the way i have open loop now is in the attached pics. What all do i need to change besides the obvious "closed loop" setting and the closed loop boost table numbers? Basically the settings on the "Boost Control Settings" form?

I'll attach the (what i think is right) closed loop settings in a second.
Attached Thumbnails
Open Loop Boost-openloopsettings.jpg  
wolfram is offline   Reply With Quote
Old 11-29-2012, 11:50 PM   #6
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default

I suppose i only change the open loop to closed loop, then start with P at 100 and I and D at 0. Slowly lower P until i dont over shoot in 2nd gear. Then add D until it holds to redline. And add I to stabilize the curve?
Attached Thumbnails
Open Loop Boost-closedloopsettings.jpg  
wolfram is offline   Reply With Quote
Old 11-29-2012, 11:58 PM   #7
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Quote:
Originally Posted by wolfram View Post
I suppose i only change the open loop to closed loop, then start with P at 100 and I and D at 0. Slowly lower P until i dont over shoot in 2nd gear. Then add D until it holds to redline. And add I to stabilize the curve?
Bingo. In my experience you need to test a few times WITHOUT TS hooked to the computer, after you feel it's dialed.
hustler is offline   Reply With Quote
Old 11-30-2012, 12:23 AM   #8
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default

Awesome. I'll give her a run!!! Thanks again!
wolfram is offline   Reply With Quote
Old 11-30-2012, 12:29 AM   #9
Junior Member
Thread Starter
 
Join Date: Apr 2012
Posts: 110
Total Cats: -3
Default

Just to be clear, closed loop should help with consistency as well as the temperature differences right? I fear that if i go tune this thing now in 25* weather, it'll be jacked when its 70* outside. Is it smart to wait for a normal 55-70* time to tune PID?

Also, if i have closed loop tuned at my current altitude ~5500ft, then take it up to say 9 or 10,000ft, that wont take into consideration the ~2psi difference will it? Not sure how the absolute barometric pressure is handled by the MS.
wolfram is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 Yesterday 09:00 PM
LucaCarMods's Boosted Dutch Miata Build! LucaCarMods Build Threads 11 02-14-2016 07:13 AM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 01:15 PM
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
Bad head gasket or ? shooterschmidty Engine Performance 8 09-30-2015 11:28 PM


Thread Tools

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:57 PM.