foff667

iTrader: (2)

I went to do a SD tune on some kids car tonight and has some major issues maybe someone can help...its a 98 m6 with minor bolt ons including headers and cutted high flow cats...he didnt have a separate o2 bung for a w/b so i just had to remove his pass o2 and put the w/b in there. I through in the base tune and went for a 25 min drive grabbed the data(pretty lean 15:1 a/f even with commanded at 12.96:1) and adjusted the main/secondary ve tables accordingly and went for another drive...minmal change...this went on for 2 more hours...got some lower cyl air cells within 3-4% high ie 13.5:1 but when id hit higher cyl air cells it would read 14.1:1-14.9:1 even with the ve at like 110-115 at those higher cells. I've done a SD tune on a 99 a few weeks back with no issues but this has me stumped...The only thing i could personally think of is maybe my w/b was off? Or needed to be recaled? I forgot to do it before i took the car down but I had just used it the other day so figured it would be cool. Anyone have any ideas of why even after several rounds of tuning the a/f wouldnt budge?

TwoFast4Lv

iTrader: (8)

Now I could be wrong , and I am every now and again, but don't both sensors need to be hooked up for the car to give you what you need? I could be wrong.

I Waited a week to start tuning on the 99 vert because it would not learn with one sensor Now I am just waiting on the Wide band to show up.

Anyway the car would not learn or move from 0.0 trims Period Runns much better with two Senser in it now!

foff667

iTrader: (2)

my thinking is you dont need to learn when your not using a maf/o2's to figure out your actual a/f...i tell it wtf to do and its supposed to do it damnit! lol

Another_User

Both front sensors have to be plugged in. There is no way around it.

foff667

iTrader: (2)

then i was doomed from the start...thanks guys but why? If in SD your not using them right...what am i missing here?

Magnus

iTrader: (4)

DId you disable closed loop after you removed an o2?

jimmyblue

iTrader: (11)

Closed/open loop distinguishes use of the O2s.
Speed density can be closed or open loop.
High CylAir is more about MAP than RPM but
high RPM pays less attention to the SD side
and more to the MAF. Every time you see an
LS1 car with half-assed mods you have to
suspect the MAF has been "improved". Even
if not, 7 years of service may have coked it
up. Whether or not the kid used a K&N. But a
lean problem that gets worse at higher airflow
implicates the MAF. Did you actually get the
MAF out of the picture or was it still meddling?

txhorns281

iTrader: (12)

There seems to be alot of confusion about the terms "SD" and "Open/Closed Loop"

Speed density is merely a mode of airflow calculation that is always being tabulated (through the VE function, which is why the VE table is our reference point when tuning) but only 100% referenced when the MAF fails. That way if our MAFs ever do die on us, we can still keep chuggin along.

SD = MAF off/ignored/broken, using VE airmass calcs to determine airflow for fueling

Open and Closed loop are just fueling modes that determine commanded AFR. When in Open loop, you are generally on a cold start, or initially in the first few moments of a startup. This does not use the O2s to control fueling. It is not an adaptive method of fueling, but a more fundamental command and receive (if tuned well) sort of operation. This is to give the O2s an opportunity to heat up and get ready to work. Once you've tripped your Closed Loop operation settings, your PCM assumes the 02s are ready to rock and switches over to reference their signals. The wonderful thing about the O2s is that they were created for one sole purpose: to keep you at stoich AFR. Now the crappy thing is they're not often very accurate or reliable. But nonetheless, the aid the fueling system by letting you know if your running too lean or too rich and will adjust fueling via trims.

Open Loop = no 02s, technically you could really run no 02 whatsoever and plug up the bungs. But know that you will be the sole compensation factor for any incorrect fueling and not the PCM. Great for tuning your core fuel reference map (VE table)

Closed Loop = O2s lit and happily making all the adjustments for you so you can just sit back and drive and know that you are chemically producing the cleanest AFR for pump gas when cruising around. That is if your tune isn't so far off that the computer has reached it's limitations to compensate. Needs to be retuned if that's the case...

You can run anyone of these 4 combos:

MAF/Open Loop - No point in this really, except PE mode.
MAF/Closed Loop - What most of us ought to be running on the street with
SD/Open Loop - VE tuning and used for track setups where the tune is stabilized for that run, on that day, in those conditions.
SD/Closed Loop - Not a good idea since we've found that the MAF helps keep fueling stable

pknowles

iTrader: (1)

You shouldn't need the front O2's if your in open loop. When I took my car in for exhaust work after I installed the headers, I loaded an openloop tune and don't have a single O2 sensor in the car. After the exhaust work was done I put the sensors back in and reloaded my closed loop tune. No codes or anything. For my openloop tune I set my closed loop enable engine temp to 240, which I would never hit so it stayed in openloop.

foff667

iTrader: (2)

http://home.comcast.net/~whenn1/SDtune6.bin
http://home.comcast.net/~whenn1/4.08.05f.hpl

here are the final tune/scan from this 98 car...take a look and open this up to some more dialog...the only thing black02ss and i could really come up with is dfco wasnt turned off...other then that **** is just retarded...FWIW i kinda gave up after SDtune3 lol so you'll see the VE is pretty jacked up/not smooth so just try and keep on topic and if you think you know what the hell I did wrong I'd really like to know for next time.

Thanks
Bill

P Mack

iTrader: (6)

It's saying the bin file is too big or something and won't let me open it. So i'm just gonna go ahead and assume you're trying to tune sd without setting the maf fail frequency to 0. So change that to 0, make sure you're making changes to both the primary and secondary ve tables (if it's 98-00) and try again. Also if you're trying to tune in open loop, you don't need the front o2's so just change the closed loop enable temp to something high.

Another_User

I see multiple issues:
1) you are right DFCO is not off...should turn it off. It is not causing you main issues
2) the car has longtubes...could cause issues since it will jack up your trims, it would be nice if you showed us a log with trims and O2 readings ya know.
3) that MAP sensor is really F-ed up. WTF did it read over 200kpa a few times? I have never seen that before.
4) why all this trouble on a car with stock heads and cam? it is pretty apparent that it is a stock cam with all that vacuum it is pulling. I can't even believe how steady the MAP readings are on that thing...

foff667

iTrader: (2)

1. like stated black02ss pointed that out

2. possibly but like stated pass side o2 was removed and w/b put in its place

3. didnt notice that till now, bad data maybe?

4. as stated customer didnt have a 3rd o2 bung otherwise i wouldve thrown it in that as I usually would do and do tuning in closed loop. I figured this way I would get his VE replotted and be able to tune fueling accuratly via pe at wot once back in closed loop.

foff667

iTrader: (2)

set to 0

replotted primary and copy/pasted cells to secondary though on the one i posted we notice i skipped a line by accident, but in all the previous ones they were fine but same result

I know, and I set the enable closed loop temps to 250

personally i think it has to do with it being a 98 maybe its just retarded lol.

Black02SS

iTrader: (36)

I would like to see what it does with the maf totally unplugged.

foff667

iTrader: (2)

maybe thats what it is...im not sure, but dont want to ask the person to keep driving out to me if i dont have a definitive cure...for that i would just ask him to throw in a 3rd bung and not worry about this crap...just thought since i had the problem maybe others had as well *shrug*