SD vs. Open Loop

[superls1]

I posted this on ls1tech, and I am still looking for me details.

Can you explain the difference or tell me where I can find the differences between SD and Open Loop? TIA.

I have been researching, but I am still confused as to "what" the actual differences are. What does the PCM do differently in SD vs Open Loop?

Just looking for knowledge. I thought SD was the PCM making decisions for fueling based primarily on MAP and RPM i.e. the VE table. I realaize there are other factors utilized (e.g. IAT, ECT, etc). There are no O2's needed in SD? A wideband would be useful, but narrowbands have no value. However, there is no "switch" or PID to indicate SD. Correct? Other key ingedient is that no MAF is used? How is commanded AFR derived in SD? Is some algorithm converting VE values into a multiplier to affect 14.7:1?

As I understand it, "Open Loop" is used by the PCM during startup and WOT. In both of these instances, the PCM ignores O2 outputs. Do fuel trims still exist during Open Loop, and do they have any effect on fueling? Do they exist in SD and/or have effect? I can change parameters in the PCM to force Open Loop all the time. If I do this, (as I understand it) Commanded AFR would be dictated by the Open Loop AFR table. What if I change WOT/PE settings to essentially have the car in PE mode at anything above idle? Is Commnaded AFR then primarily (or solely) driven by PE vs RPM table? Do fuel trims exist and/or have any impact in Open Loop/PE mode?

Sorry for all the questions, I just haven't ever seen where this has been laid out nicely. Instead, I seem to find conflicting information from all the sites I keep reading. Maybe I just need to step away from the internet.

[bink]

I posted this on ls1tech, and I am still looking for me details.

Can you explain the difference or tell me where I can find the differences between SD and Open Loop? TIA.

I have been researching, but I am still confused as to "what" the actual differences are. What does the PCM do differently in SD vs Open Loop?



Open Loop - NO O2 sensor input. I.E. -> NO sensor sensor feedback therefore the loop is not closed.

Closed Loop. O2 sensor feedback to the PCM. The loop is closed - as the pcm sends out signals to injectors the O2 sensors reports back the AFR (equivalence ratio) and then the PCM further adjusts. Actually is more complicated but this is the general idea.

Speed Density -> MAFLESS operation. There is no MAF sensor providing mass airflow quantities. The PCM determines the neccessary Fuel and Spark from lookup tables ( VE, Spark, IFR etc.).
Speed Density may be Open Loop (no O2 feedback) or Closed Loop (O2 feedback to the PCM).



How is commanded AFR derived in SD?

Open Loop AFR table and The PE table. PE table is enabled by temp, MAP and TPS%.
Or if Closed Loop SD via the LTFTs, STFTs and PE.


Do fuel trims still exist during Open Loop, and do they have any effect on fueling?

No.


Do they exist in SD and/or have effect?

If you run SD closed loop they will update and have an effect ( I believe this is accurate ..if not someone please correct me)


I can change parameters in the PCM to force Open Loop all the time. If I do this, (as I understand it) Commanded AFR would be dictated by the Open Loop AFR table. What if I change WOT/PE settings to essentially have the car in PE mode at anything above idle?
You can set iyour car up, for open loop, by setting the enable temp to a very high value. You can run it through the PE table by setting the enable TPS% to just above idle. I tried it and didn't like it. My car "shuddered" each time it transitioned between PE and nonPE (Open Loop AFR table ). I don't think my car liked it much either.
Yes, you could also do this "closed Loop". The car would have active O2 sensors at idle and the sensors would be ignore at all PE settings.
I don't see any advantage to limiting your fueling to the PE table??(I tried this too. It was long ago before we knew how to create new VE tables......it didn't work out. I tried a lot of things!!)



Instead, I seem to find conflicting information from all the sites I keep reading. Maybe I just need to step away from the internet.
There is a lot of myth and bunk out there - much of it is historical.....we/they/people didn't know any better back then. There is much more known today about the PCM and tuning than even a year ago.
Stick to this site, and LS1Tech, and you'll have the most accurate info available. The guys around here are great....and a big help.

Don't give up. The net is your friend! :D

Hope this helps some.

Cheers,
joel

PS - try to ask fewer questions per post. I'm not ragging :lol: - you'll have a better chance of quick answers with short 1 or 2 question posts.
FWIW.

[superls1]

Thanks. I will try to ask fewer questions. :) Guess I had learned more than I thought. I pretty much had those answers in mind.

Only 2 questions:

1) Why do you run Open Loop?

2) Why don't more people post their VE tables (in your opinion)? VE tuning seems to be all the rave the past several months, but rarely are real results posted. Even on most the tune/bin repositories, it is hard to find any with VE modifications other than idle RPM area.

[SinisterSS]

If everyone was tuning a stock automobile, the VEs could be shared. Since everyone has their own combination of CAI, exhaust, cams, heads, gasoline, elevation, etc. the VE tables are unique. A simple copy and paste of the VE isn't the best way to tune.

With AutoVE, it is a relatively simple process to dial in the VE map.

[superls1]

Agreed that people have different variables, but I would imagine there are many similarly equipped cars in a given locale (e.g. I am sure there are a number of F-bodies in the Houston area with similar MTI setups). I doubt the VE would really vary much for them even if one had Brand X headers and another had Brand Y. Yet, noboby posts up their results. I see many people that post here also post on other boards. I created a topic here asking to some big cube VE tables, but no one ever posted their results. The LS1Edit and HPTuners repositories also have very few (if any) tunes indicating VE mods other than idle changes.

There was a post on ls1tech were several people posted graphs. But for the overall number of people attempting to tune their cars, I am just wondering if not that many people are doing it, if it is still not understood/trusted as a method, too "secretive" to divulge, etc.

I appreciate the tunes on your site. Do you have any modified files, or did I just miss them?

Here is the thread I created:
http://www.efilive.com/forum/viewtopic.php?t=1725

[Nox]

alot of tuners use injector pulse width or some other method of controlling the afr and fuel. alot has been learned recently. only a few people are using "autotuning", not many ecu's feature it. i think autronic was the first. with the setup they have you just need to dial in one cell and it fills in the rest with amazing accuarcy.

i also think that alot of tuners are protecting the investment they have in classes, books, dyno time, real life lessons, etc.... that they have spent time and money on. personally i think that they are a little to closed lip sometimes. i wouldnt expect them to post up actual tunes or maps, but general guidelines or steps, or specific MAPS to look at would benefit everyone.

there is no "magic" to tuning. alot of them just don't want you to look behind the big curtain. "ignore the man behind the curtain and look at me the great waizard of tuning OZ"

i am no great tuner. i am still learning alot. but i can tell you this - if you have patience, and do your homework on the internet and the 4 or 5 good books that are out there you can learn alot. the issue for me is tuning with the software and learning it. especially what to do in different boosted applications, that were not originall FI applications.

figuring out WOT tuning is the easy part. decide what AFR you want and adjust fueling (however you do that in your system), then adjust timing up until you show no improvement in tractive effort. pull it back until you show a loss in tractive effort, then tweak the difference. (assuming no knock)

it is the rest that takes time and is different on every car, that is why the SD VE autotune is so cool. you can dial in the VE so quickly.

keep plugging along.

[Tydriver]

i am no great tuner. i am still learning alot. but i can tell you this - if you have patience, and do your homework on the internet and the 4 or 5 good books that are out there you can learn alot. the issue for me is tuning with the software and learning it. especially what to do in different boosted applications, that were not originall FI applications..


Any recommendations you'd like to share with the BOOKs? I'm all over reading and learning.. Sometimes its best to have someone spoon feed ya on occasion as well :wink:

I'm willing to do the work and learn but people are so unwilling to share information sometimes its depressing..

Guess its the BMOC complex..

[Nox]

Any recommendations you'd like to share with the BOOKs? I'm all over reading and learning.. Sometimes its best to have someone spoon feed ya on occasion as well :wink:

I'm willing to do the work and learn but people are so unwilling to share information sometimes its depressing..

Guess its the BMOC complex..

ben straders book is a good general overview of efi systems and how they work. it also reviews the different EMS's on the market.

jeff hartman's book is an excellent resource with a little more in depth discussion of actual tuning, as well as several real world case studies.

Tuning Accel/Dfi 6.0 Programmable Fuel Injection by Ray something? is in my opinion a great resource. it focuses on the accel products, and is a little dated, but you can apply the information about tuning to any setup. i really think it is one of the hidden jewels. it covers an A-Z of how to tune a car with the ACCEl ECM, but you can follow the steps with just about any system. The setup uses pulsewidths for fuel, were we use VE and CAFR, but the principles are still the same.

After reading these and wading thru all the info on the net, then take Ben Strader's EFI 101 class. It is a real eye opener. After the class, go back and reread alll of the books.

What gets me is that I would like to see some how to's about efi live. every body says that the purpose of this forum and the software is not to teach people how to tune. that is fine with me. i dont want anyone to tell me what values to enter, what A/F ratio to run with XYZ setup, how much timing an XYZ setup needs etc.... But, it sure as hell would be nice to know in this software what the exact steps are for say converting to a 2BAR setup, or what tables to examine if you are having an issue with XYZ... In my opinion that is software support, not tuning.

It is learning the software that is the big issue once you get the tuning basics down. I went thru it with my EVO, my Focus, HP Tuners with my WS6, and now EFI Live with my GTO.

I love EFI Live. I switched from HP Tuners on the suggestion of an author of one of the aforementioned books. If you hang in there the rewards are worth the effort.

[bink]

i am no great tuner. i am still learning alot. but i can tell you this - if you have patience, and do your homework on the internet and the 4 or 5 good books that are out there you can learn alot. the issue for me is tuning with the software and learning it. especially what to do in different boosted applications, that were not originall FI applications..


Any recommendations you'd like to share with the BOOKs? I'm all over reading and learning.. Sometimes its best to have someone spoon feed ya on occasion as well :wink:

I'm willing to do the work and learn but people are so unwilling to share information sometimes its depressing..

Guess its the BMOC complex..

Here are some decent books from the thread here->
http://www.efilive.com/forum/viewtopic.php?t=1177&postdays=0&postorder=asc&start=15

bink
Lifetime member



Joined: 19 Oct 2003
Posts: 268
Location: ohio
Posted: Sat Feb 05, 2005 3:33 pm Post subject: books on tuning

--------------------------------------------------------------------------------

Although these books are not LS1/LS6 specific I've found them helpful in theory and practice.
They are not pro level but they have been very helpful at my level (amateur/tinkerer).

"Engine Management -optimising carburettors, fuel injection and ignition systems"
by Dave Walker. Haynes High Performance tuning series.

"How to Tune and Modify Engine Management systems"
by Jeff hartman. Motorbooks Workshop

"Building and Tuning High-Performance Electronic Fuel Injection"
by Ben Strader. S-A Design, CarTech Books

"Tuning Accel/DFI 6.0 Programmable Fuel Injection"
by Ray T. Bohacz. HPBooks

General Engine Info:

"Introduction to Internal Combustion Engines"
by Richard Stone. SAE International

I think you will find that "part throttle " tuning is more complex than most realize. Each setup is unique. You pretty much need to have a solid working knowledge of engine dynamics (valve timing, ignition timing etc.)


What is the BMOC Complex??

Cheers,
joel

[superls1]

Damn it Bink. :wink: As I was typing my response, you posted yours. I would add the Probst book

http://www.amazon.com/exec/obidos/tg/detail/-/0837608619/qid=1121105247/sr=8-1/ref=sr_8_xs_ap_i1_xgl14/104-8968270-1375168?v=glance&s=books&n=507846

There is some good stuff in there as well.

BTW, I would like to know what BMOC is as well. Is it "Big Man on Campus"?

[Tydriver]

BTW, I would like to know what BMOC is as well. Is it "Big Man on Campus"?

Thanks everyone for the links. I will try to score some of these books..

And yes.. BMOC = Big Man On Campus.. Basically, wants everyone to envy him and not willing to share.. Fortunately, there is VERY LITTLE of this here and I have ALOT to learn.. LOL

[bink]

Damn it Bink. :wink: As I was typing my response, you posted yours. I would add the Probst book

http://www.amazon.com/exec/obidos/tg/detail/-/0837608619/qid=1121105247/sr=8-1/ref=sr_8_xs_ap_i1_xgl14/104-8968270-1375168?v=glance&s=books&n=507846

There is some good stuff in there as well.

BTW, I would like to know what BMOC is as well. Is it "Big Man on Campus"?

Probst was the first tuning book I read. I would agree it's worthwhile.

The GEN III Eng Management pdf. is excellent also-> http://www.hsvdriversclub.co.uk/ls1.pdf

Cheers,
joel

[bink]

BTW, I would like to know what BMOC is as well. Is it "Big Man on Campus"?



And yes.. BMOC = Big Man On Campus.. Basically, wants everyone to envy him and not willing to share.. Fortunately, there is VERY LITTLE of this here and I have ALOT to learn.. LOL

I have seen very few BMOC types in tuning on this board or LS1Tech. In fact most of those who knew the most were often the most willing to help.

The Supreme Sage -> NoGo. NoGo was light years ahead and willing to share....amazing guy. :mrgreen:

[superls1]

Thanks everyone for the links. I will try to score some of these books..

FYI, you can get a free copy of Ben Strader's book on this site just by having 20 posts in the Tuning section. At least, I think you still can.

[Nox]

his published book, or the efi 101 workbook? both are excellent.

[GMPX]

FYI, you can get a free copy of Ben Strader's book on this site just by having 20 posts in the Tuning section. At least, I think you still can.

Hey Ben, can I just post 'I want a free book' twenty times :lol:

Cheers,
Ross

[Scoota]

FYI, you can get a free copy of Ben Strader's book on this site just by having 20 posts in the Tuning section. At least, I think you still can.

Hey Ben, can I just post 'I want a free book' twenty times :lol:

Cheers,
Ross
Just what is it that you think you’re going to learn from that book that you wouldn't already know Ross? "What" you think it might look good on the bedside table.:idea: :twisted: :wink:

Cheers, Scooty.

[BowlingSS]

Thanks everyone for the links. I will try to score some of these books..

FYI, you can get a free copy of Ben Strader's book on this site just by having 20 posts in the Tuning section. At least, I think you still can.

How do I get a free book?

Bill

[BowlingSS]

Just finished my SD Autotune today after removing the MAF. Now to check out the PE table and make sure my trims are good.
Thanks, FlashScan for making it sooo easy.
Bill
:D

[superls1]

Sorry, the book can be obtained by having 20 posts in the tuning forum on this site: http://www.gearchatter.com

[BowlingSS]

Sorry, the book can be obtained by having 20 posts in the tuning forum on this site: http://www.gearchatter.com
Just what I need is another forum to keep up with..

Bill
:D