Temp question (Topic Split) - Page 2

Shorty · 01-13-2005, 09:22 AM

does anyone have a good link to describe what the differences in open and closed loop is? i have heard you all talk about it alot but dont know what you are actually talking about.

Italian LX · 01-13-2005, 09:30 AM

Quote:

Originally Posted by Shorty

does anyone have a good link to describe what the differences in open and closed loop is? i have heard you all talk about it alot but dont know what you are actually talking about.

Quick description:

Open loop uses a set table and the reading from the MAF to determine injector pulse width.

Closed loop uses the above in conjunction with feedback from the O2 sensors; the computer then comes up with a trim value that adjusts the injector pulse width in order to get closer to the commanded A/F ratio.

There are other parameters involved, but the above is simplidied to show the difference between OL and CL.

QWKSNKE · 01-13-2005, 09:31 AM

Also

Open loop is used during WOT and initial startup.

QWKSNKE · 01-13-2005, 09:40 AM

Quote:

Originally Posted by Wicked

Noone said that, TwEECer is not a stock ECU though right?

I know you didn't say that. Didn't mean it in a sarcastic manner

Shorty · 01-13-2005, 09:56 AM

so during most driving conditions the EEC is in CL. meaning that if the 02's were missing some, that the A\F would suffer. my car ran a little lean on the dyno and on initial start it wants to go dead the first time you turn it over. this was never an issue before the headers and O/R H-pipe.

TheJeanyus · 01-13-2005, 10:01 AM

Quote:

Originally Posted by Shorty

so during most driving conditions the EEC is in CL. meaning that if the 02's were missing some, that the A\F would suffer. my car ran a little lean on the dyno and on initial start it wants to go dead the first time you turn it over. this was never an issue before the headers and O/R H-pipe.

It's broken for good. You should just let me have it.

Italian LX · 01-13-2005, 10:02 AM

Quote:

Originally Posted by Shorty

so during most driving conditions the EEC is in CL. meaning that if the 02's were missing some, that the A\F would suffer. my car ran a little lean on the dyno and on initial start it wants to go dead the first time you turn it over. this was never an issue before the headers and O/R H-pipe.

Your dyno A/F (for the most part) has nothing to do with your O2 sensors because the CPU goes into OL under WOT.

On the otherhand, your O2 sensors do affect your trim tables which the computer will use during OL operation to adjust the pulse width according to previous logs.

Shorty · 01-13-2005, 10:13 AM

Quote:

Originally Posted by Italian LX

Your dyno A/F (for the most part) has nothing to do with your O2 sensors because the CPU goes into OL under WOT.

that would have made sense if i would have thought a little harder.

Quote:

Originally Posted by Jeanyus

It's broken for good. You should just let me have it.

should make you a good DD.

93Cobra#2771 · 01-13-2005, 11:44 AM

Here's a nice little spreadsheet I have compiled with all kinds of fun stuff on it. Although it is Fox specific, a lot of the descriptions and functions are very similar on 94+ stuff.

BTW, this is the list of tweecer paramters on the fox stuff...

Well, my file is too big to attach here (xls spreadsheet). I'll copy and paste a few things, and give a link to it in the yahoo tweecer group (you have to join to see it, but no big deal).

http://autos.groups.yahoo.com/group/...Documentation/
It is the file called "tweecer defs.XXXXXX.xls. I update it and change the X to the date it is updated.

Closed Loop: "Closed loop refers to the EEC watching the Oxygen sensors and monitoring and adjusting a/f to achieve stoichemetric. Closed Loop occurs at all times other than WOT and the first 120 seconds or less after startup. KAMRF values at this time are 1.000. To disable, adjust the min load for closed loop fuel control to a load the car will never see & number of hegos to "0". Adaptive should also be disabled at this time. This is also known as "Forcing Open Loop". A variant of that is to set the min load to a load the car never sees at idle, this will "Force Open Loop at Idle"."

Open Loop basically ignores O2's and works off tables.

93Cobra#2771 · 01-13-2005, 11:51 AM

Quote:

Your dyno A/F (for the most part) has nothing to do with your O2 sensors because the CPU goes into OL under WOT.

On the otherhand, your O2 sensors do affect your trim tables which the computer will use during OL operation to adjust the pulse width according to previous logs.

Italian made a very important poinit. In other words, IF the EEC sees the load/rpm conditions in CL operation, it can apply adaptive long term memory to OL WOT runs. So, adaptive CAN affect your WOT dyno tune IF you raised fuel pressure to get more fuel at WOT.

Do a dyno tune and raise the FP to get more fuel and get your a/f just right. Then go back in a few months, don't touch anything, and more times than not, your a/f will be leaner than what it was. Kinda scary, huh?

01-13-2005, 09:22 AM	#11
Shorty Pr0j3ct P1mp T1t3, y0! Join Date: Dec 2004 Location: Somewhere wondering why Crimson stole my avatar Posts: 2,022	Re: Temp question does anyone have a good link to describe what the differences in open and closed loop is? i have heard you all talk about it alot but dont know what you are actually talking about. __________________ 93 GT----225rwhp/287rwtq--------1/4 mile= (but getting better)

01-13-2005, 09:31 AM	#13
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Re: Temp question Also Open loop is used during WOT and initial startup. __________________ 2009 Porsche Carrera S 2008 ///AMG C63.. Eurocharge Tune. RIP 2019 AMG GLC43..wife's 03 F250 SD.. Edge Evo, AFE Stage 1 CAI 08 GT. JBA axle back, FRPP springs, FRPP swaybars.. daughter's 01 Cobra vert... wife's I need a new toy

01-13-2005, 09:56 AM	#15
Shorty Pr0j3ct P1mp T1t3, y0! Join Date: Dec 2004 Location: Somewhere wondering why Crimson stole my avatar Posts: 2,022	Re: Temp question (Topic Split) so during most driving conditions the EEC is in CL. meaning that if the 02's were missing some, that the A\F would suffer. my car ran a little lean on the dyno and on initial start it wants to go dead the first time you turn it over. this was never an issue before the headers and O/R H-pipe. __________________ 93 GT----225rwhp/287rwtq--------1/4 mile= (but getting better)

01-13-2005, 11:44 AM	#19
93Cobra#2771 The Kocky One Join Date: Dec 2004 Location: Yeah, but those cutters won't bust any walnuts.â„¢ Posts: 1,948	Re: Temp question (Topic Split) Here's a nice little spreadsheet I have compiled with all kinds of fun stuff on it. Although it is Fox specific, a lot of the descriptions and functions are very similar on 94+ stuff. BTW, this is the list of tweecer paramters on the fox stuff... Well, my file is too big to attach here (xls spreadsheet). I'll copy and paste a few things, and give a link to it in the yahoo tweecer group (you have to join to see it, but no big deal). http://autos.groups.yahoo.com/group/...Documentation/ It is the file called "tweecer defs.XXXXXX.xls. I update it and change the X to the date it is updated. Closed Loop: "Closed loop refers to the EEC watching the Oxygen sensors and monitoring and adjusting a/f to achieve stoichemetric. Closed Loop occurs at all times other than WOT and the first 120 seconds or less after startup. KAMRF values at this time are 1.000. To disable, adjust the min load for closed loop fuel control to a load the car will never see & number of hegos to "0". Adaptive should also be disabled at this time. This is also known as "Forcing Open Loop". A variant of that is to set the min load to a load the car never sees at idle, this will "Force Open Loop at Idle"." Open Loop basically ignores O2's and works off tables. __________________ *For Sale: Reproduction Window Stickers, 87+ Mustangs, Cobras, Lightnings, and HD F150!* Richard White 93 Cobra Kocky will be back!