PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Open Loop/Speed Density questions

Thread Tools
 
Search this Thread
 
Old Mar 13, 2008 | 07:31 PM
  #1  
ProgGod's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2004
Posts: 103
Likes: 0
Default Open Loop/Speed Density questions

Is there any reason not to set the car to stay in open loop mode all the time? One of my O2 sensors is reading way off. I think it got damaged, and was thinking about tuning the car to stay in open loop mode all the time. Is this a bad or good idea? I was also thinking doing a speed density tune and elimating the MAF at the same time would be a good idea. This is a 600rwhp N/A motor.
Reply
Old Mar 13, 2008 | 10:54 PM
  #2  
MarcouxTA's Avatar
Registered User
 
Joined: Mar 2008
Posts: 11
Likes: 0
From: ontario, canada
Default

if you get rid of the maf and the rear O2, and run in open loop all the time you will run on a "pre programed" stoic ratio and loose a lot of fuel control!!
Reply
Old Mar 13, 2008 | 11:13 PM
  #3  
ProgGod's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2004
Posts: 103
Likes: 0
Default

What do you mean, how so?
Reply
Old Mar 13, 2008 | 11:22 PM
  #4  
MarcouxTA's Avatar
Registered User
 
Joined: Mar 2008
Posts: 11
Likes: 0
From: ontario, canada
Default

the maf tells the PCM how much air is entering the engine, if it even gets dirty it will give you issues. Removing it will force you to run in "limp in mode" or controled open loop!
Reply
Old Mar 13, 2008 | 11:36 PM
  #5  
sroach20's Avatar
TECH Addict
iTrader: (31)
 
Joined: Dec 2002
Posts: 2,318
Likes: 1
From: houston, Texas
Default

speed density is great as long as you can get everything dialed in. plus you dont have to worry about maxing out the maf.
Reply
Old Mar 13, 2008 | 11:38 PM
  #6  
LS1W's Avatar
On The Tree
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (89)
 
Joined: Mar 2007
Posts: 124
Likes: 0
From: Riverside, CA
Default open loop

not to be a wise guy, but - if you want to run in open loop all the time then trade in all your fi for a carburetor

with one exception ( msd's mefi-iv unit ) i have never had good driveability with open loop / speed density type systems

just my opinion.................
Reply
Old Mar 14, 2008 | 01:12 AM
  #7  
macca_779's Avatar
TECH Enthusiast
 
Joined: Nov 2006
Posts: 620
Likes: 0
From: Katherine N.T Australia
Default

Nothing wrong with OLSD. I run it pretty much in most conditions in my tune. Use a custom OS with a VE/IAT factor, dial in the VE at one temperature then check the VE at different temps and apply the AFR BEN to the VE/IAT table. I don't believe HPT has this feature so that will make it very difficult to get OLSD fuel calculations as accurate as you can in EFI LIVE, still its doable and far superior to MAF fueling when done correctly.
Reply
Old Mar 14, 2008 | 02:32 AM
  #8  
ProgGod's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2004
Posts: 103
Likes: 0
Default

It makes sense to do it to me. I can dial in my tune for the air density/temperature of the day right before I race. I don't have to worry about the car reacting after the fact. The O2 sensor is only used at part throttle operations. Its main purpose is to give me best fuel economy during cruising. My car is going to be raced 90% of the time. So using the O2 seems pointless.

As for speed density mode, the MAF is just restricting the air flow. Its not going to be as accurate of a gauge of air flow during racing conditions.

I guess my real quick is has anyone had success in doing both? Is it worth the trouble of having to check my tunes during races?
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

 Brett Foote
story-1

Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

 Pouria Savadkouei
story-2

Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

 Verdad Gallardo
story-3

7 Most Reliable High-Performance Engines GM Has Ever Built

 Verdad Gallardo
story-4

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-5

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-6

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-7

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-8

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-9

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
Old Mar 14, 2008 | 02:33 AM
  #9  
ProgGod's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2004
Posts: 103
Likes: 0
Default

Oh and are you joking with the carb remark? Do you even know how a pcm works? Last time I checked a carb can't give me perfect amount of fuel and timing for each individual rpm spot?
Reply
Old Mar 14, 2008 | 02:45 AM
  #10  
TAQuickness's Avatar
TECH Junkie
iTrader: (28)
 
Joined: Jan 2004
Posts: 3,250
Likes: 1
From: Houston
Default

I've been running OLSD for about 3 years now. The bird has stock like manners thru school zones, get's 22 mpg on the hiway and puts down a little shy of 500/500 on the rear wheels. EFILive's custom OS 5 (for the 99+ 512 pcms) is a big contributing factor for this.
Reply
Old Mar 14, 2008 | 07:09 AM
  #11  
Eurospec2's Avatar
FormerVendor
iTrader: (2)
 
Joined: May 2007
Posts: 668
Likes: 0
From: Jacksonville Florida
Default

Originally Posted by MarcouxTA
if you get rid of the maf and the rear O2, and run in open loop all the time you will run on a "pre programed" stoic ratio and loose a lot of fuel control!!
In OLSD you actually GAIN complete control of your commanded fueling, you dont loose anything.

Ive been running OLSD for as long as i remember, it takes a bit of tuning to get it right but once it is set, i much prefer it to closed loop maf.
Reply
Old Mar 14, 2008 | 11:25 AM
  #12  
ProgGod's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2004
Posts: 103
Likes: 0
Default

Originally Posted by Eurospec2
In OLSD you actually GAIN complete control of your commanded fueling, you dont loose anything.

Ive been running OLSD for as long as i remember, it takes a bit of tuning to get it right but once it is set, i much prefer it to closed loop maf.

How do I completely disable closed loop mode?
Reply
Old Mar 14, 2008 | 11:26 AM
  #13  
ProgGod's Avatar
Thread Starter
On The Tree
 
Joined: Jun 2004
Posts: 103
Likes: 0
Default

You guys are all making me want to switch to EFI. I just bought HPT too
Reply
Old Mar 14, 2008 | 11:32 AM
  #14  
brad8266's Avatar
TECH Senior Member
iTrader: (23)
 
Joined: Aug 2005
Posts: 8,797
Likes: 0
From: Watertown, NY
Default

OLSD is not really a good first step for you if you are new to tuning, it takes a good tuning knowledge base to get. If you cant tune then dont jump right into it.
Reply
Old Mar 14, 2008 | 05:22 PM
  #15  
Billf6531's Avatar
Staging Lane
 
Joined: Jan 2004
Posts: 84
Likes: 0
From: Calgary, Alberta, Canada
Default

Set the Closed Loop Enable ECT vs. IAT to its maximum value.

Originally Posted by ProgGod
How do I completely disable closed loop mode?
Reply
Old Mar 14, 2008 | 06:19 PM
  #16  
VH5150's Avatar
Dynojet Fan
 
Joined: Jul 2007
Posts: 342
Likes: 0
From: Mass.
Default

I just started doing the olsd tuning the other day.. Its kinda confusing/annoying at first, but eventually it makes sense... W/ my cam the car idles at 80-85kpa...
Reply
Old Mar 14, 2008 | 07:43 PM
  #17  
Frost's Avatar
FormerVendor
iTrader: (45)
 
Joined: Jul 2005
Posts: 5,913
Likes: 2
From: Richmond VA
Default

Alpha N!
Reply
Old Mar 14, 2008 | 09:55 PM
  #18  
Eurospec2's Avatar
FormerVendor
iTrader: (2)
 
Joined: May 2007
Posts: 668
Likes: 0
From: Jacksonville Florida
Default

Originally Posted by Frost
Alpha N!
Reply
Old Mar 15, 2008 | 12:43 AM
  #19  
VH5150's Avatar
Dynojet Fan
 
Joined: Jul 2007
Posts: 342
Likes: 0
From: Mass.
Default

alpha-n, isnt that in efi's cos5?? VE based on throttle %...

Last edited by VH5150; Mar 15, 2008 at 01:20 AM.
Reply
Old Mar 15, 2008 | 06:19 AM
  #20  
TAQuickness's Avatar
TECH Junkie
iTrader: (28)
 
Joined: Jan 2004
Posts: 3,250
Likes: 1
From: Houston
Default

yessir.
Reply



All times are GMT -5. The time now is 05:10 AM.

story-0
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

Don't get dad new socks or a grill brush this year.

By Brett Foote | 2026-06-09 14:55:56


VIEW MORE
story-1
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-2
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-3
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-4
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-5
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-6
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-7
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-8
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-9
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE