V8Astro Captain

iTrader: (1)

Which one should I tune by? I got a good response on another related question, but I'm still not sure whether I should tune using the INT or the BLM.

I'm trying to get my pumpshot up, but it seems that it's making it too rich all the time. I compensated by lowering the VE #2 table, but I don't think it helped much. I did this in response to an archive post from Pablo I read, he said he moved his pumpshot up really far. I tried and now it seems I'm too rich.

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'92 Astro, GM crate 350, Performer TBI intake, MSD 6AL, 3.42's, 2.5" exhaust, Flowmaster 40 2 chamber, B&M 2nd stage shift kit, 255 60 R15 tires on AR-727's, Polished & Bored TBI, Custom EPROM in progress

[This message has been edited by V8Astro Captain (edited October 21, 2001).]

hectorsn

BLM first, then INT.

GregWestphal

iTrader: (1)

As hectorsn said, tune by BLM first, then by INT. The pumpshot only affects the A/F ratio for maybe 1 second at the most when you hit the gas pedal. You probably need to tune your first VE table unless you're only tuning at WOT. Anything beyond this, you'll need advice from somebody that actually has or tunes SD or TBI cars.

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Greg Westphal
'87 IROC 355TPI/A4

fast_broker

iTrader: (1)

I never tune to INT. BLM is the "coarse" tuning tool and each BLM move is 1/128 percent, or .78%, which is a fine enough adjustment for anyone. Especially considering altitude, daily temperature and normal daily barometer changes will have an effect on required fuel to a degree that approches at least that much... INT is essential a further breakdown of BLM, which would be ideal to tune with if ALL OF YOUR BLM's are at 128, which I have never seen anyone get to. ever...

If you can get ALL of your closed-loop BLM's at 128, you're a better man than me... I can get between 126 and 130 pretty good, but all 128's will never happen. Unless I get my ALDL cable and use that free software??? Maybe that'll make my life easier. Still waiting.

EDIT: BLM of 117 means that that you are about 8.5% rich, which is quite a lot. You need to multiply the VE value in the appropriate RPM/MAP cell by .915 and input the new value in the cell for your next PROM.

[This message has been edited by fast_broker (edited October 22, 2001).]

V8Astro Captain

iTrader: (1)

I'll try that. Any reason why I should use .915? Is this the % error or something? Thanks.

fast_broker

iTrader: (1)

I'm sorry.

You said your BLM was 117 and it should be 128... so:

117/128 = .9140625

Multiply your VE table number by .9140625 which will LEAN out the cell.

Get it???


Likewise, if you are lean, and say your BLM is 139, you get 139/128 = 1.0859375. Multiply your cell value by that number, which will RICHEN your cell area...


FYI, In Tunercat, you can only use like .4 as the increments in the VE cells, anyways, which is A LARGE PERCENTAGE, like from 1.3% to .4%, depending on the cell value you are changing!! (ie the cell value can be 30, or can be 99!!!) Just seems that INT is TOO FINE a tuner for what we use to program with. ie, INT is much finer than the actual percentage change you can actually implement with tunercat...

I guess what I am trying to say is don't pay any attention to INTt but try to get your BLM's as close to 128 as you can.

[This message has been edited by fast_broker (edited October 22, 2001).]

V8Astro Captain

iTrader: (1)

thanks again.

David 91RS/Z28

Thanks as well! I've been wondering if there was a formula to figure out VE.



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David Tuschhoff
1991 RS/Z28 Camaro
FI 355ci NA SBC V8 M5.
12.47 @ 110.7mph 1.80 60'
Best mph of 111.6.
My f-body page!

fast_broker

iTrader: (1)

An addendum to the above, in regards to a 1227747 TBI ECU:

If you are running an OEM type PROM, there are two fuel tables in use, Main #1 and Main #2. These are added together inside the PROM for overall fuel delivery. If you just multiply the Main #1 table by the correction value, it IS NOT A COMPLETE adjustment. You must multiply the correction value by (Main #1 + Main #2) and get a new number. Then, subtract Main #2 from the new number to get the Main #1 NEW VALUE.

I do not use the Main #2 table at all and have it all set to "0" so that the MAIN #1 table is all that requires changes. ie, easier.

I have heard not to keep the Main #2 values at pure "0" (ie, leave them at .4) because the ECU will wig-out, but I have not had any problems...


EDIT:
Example using OEM PROM system:

Main#1 = 50
Main#2 = 40 (total = 90)
BLM = 117 (rich)

[117/128*(50+40)]-40= 42.3 = new Main#1 value to correct the 117BLM to a 128BLM, total fuel now = 82.3 (ie, 42.3+40 from new #1+#2 values)


Same situation USING Main#1 table only method:
Main#1 = 90

(117/128)*90= 82.3 = new total fuel and Main#1 value


[This message has been edited by fast_broker (edited October 26, 2001).]

afgun

Does this Main 1&2 hold true for all bins ?

fast_broker

iTrader: (1)

No idea. My example is for a 1227747 TBI PROM...

V8Astro Captain

iTrader: (1)

Hey Fast_Broker, check your mail. I sent you alot of stuff I'm hoping you can help me with.

Lionsden

I guess I'm confused now. I'm tuning a 7747 and have locked the BLM to 128. With Ease and Joby's Winaldl I'm adjusting the fuel table for a 128 INT. Is this not the right way to do it? Is there a better way?



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Dan

V8Astro Captain

iTrader: (1)

You got it better than me if you can! If I set my BLM to 128 to try to tune the INT, I get a SES light.

One thing I noticed was, my van idles like a dream if the BLM in that area are 130 and 135. If I even dare to get them at 128, the van starts rumbling. When I lean it out again, it idles smooth as silk.

Right now I had to change my BPW (137) and VE #2 (droppped 2000-2400 rpm 6 points) table just to get my BLM's in the 122-125 area. I think I'm gonna leave it alone for a while because it runs better than ever.

As for the BLM and INT thing, I was told by all the pro's that I should be tuning the BLM first, b/c it's a more "coarse" adjustment.

[This message has been edited by V8Astro Captain (edited October 31, 2001).]

Grim Reaper

Ultimately, this is what you want to do to get it exact. The adjusting on the BLMs first, is to get "major adjustments/corrections" done as quickly as possible. Think of it like using a "plane" on a block of wood.

Once you have gotten the BLMs "reasonably close", then lock the BLM and adjust on the INTs only. Think of it like using "sandpapper" to finish that block of wood.

The BLMs and INTs do interact with each other, and can give "unusual" results the first time you unlock the BLM and cleared the ECM. But after a bit of driving it starts to "settle down" and give proper values.

fast_broker

iTrader: (1)

Glenn is right. If you want to lock BLM and use INT, you should get BLM as close to 128 as possible. The VE adjustment increment in Tunercat is about the same as a BLM adjustment (little less, little more), so for me, tuning to INT doesn;t make much sense. INT is too fine for me. whatever works, I guess. If I get BLM's at 126-130, the vehicle runs very well. That is only a 1.5% error in fuel, too. ie, 2/128. I can live with that and let the ECU/INT do the rest while I drive. Tuning to INT with locked BLM is impossible if your BLM's are off as far as V8Astro's are, anyway... Trust me, get the BLM's near 128 and you will be happy.

V8, are you having problems in Open loop idle or closed-loop idle? you will have to change the open-loop idle AF parameters to get it to run right. Also, when you are in Clsoed-loop at idle under same RPM/MAP conditions, it doesn't matter if the BLM is 128 or 140 or 110. The AF will be tweaked to the proper amount at that condition after things settle out and idle quality should be the same. Now, OPEN-loop idle quality will vary greatly with VE changes at idle areas of RPM/MAP!!!

That WinALDL program is awesome for BLM work. Truly awesome. I am now working on repeatability testing of the program to see if I keep getting similar BLM data over several runs/clears/runs/clears... Is has to be repeatable to be good BLM-to-VE change data. ie, accurate.

V8Astro Captain

iTrader: (1)

The idle wobbles during open loop sometimes. But it evens out after a couple seconds.

The smooth idle I mentioned is in closed loop. Someone told me to even out the timing cells at idle, I did and it helped alot. What also helped was I lowered the IAC step Vs Coolant at operating temp. I read a whole bunch of info and the fella who wrote it said he liked to set the steps on the low side and let the ECM "catch" the idle, using values in the idle speed Vs coolant temp.

I don't know why but when I get the BLM's around 130-135 it seems to idle smoother. No joke, I've gone back and forth between adjustments on a couple chips and this is what I found each time. I'm just doing what makes me feel better about the situation.

I'll flatten out the idle area of the VE table and see what happens, like you said.

One last question. If my engine idles right around 29-35 kPa (depending on temp), should I use the 30 or 40 kPa cell? Or both?

[This message has been edited by V8Astro Captain (edited October 31, 2001).]

[This message has been edited by V8Astro Captain (edited October 31, 2001).]

Lionsden

Could the reason I am getting away with locking the BLM at 128 and tuning with INT be that the fuel table wasn't that far off to begin with? Right now with BLM locked the INT runs from about 123 to 133 on most cells.

More as a learning and comparing experience than anything I'm scanning with two laptops at the same time. One with Winaldl and the other with Ease.

After a run I print the four INT tables from Winaldl then compare those with the Ease scan. To get the most accurate Winaldl tables I will wait to start the program after I'm at cruise or under load on the highway. The best "feel" of the Winaldl tables are when they are view as a whole and not by focusing in on individual cells. comparing multiple scans seem to support this.

Anyone have additional comments?

Still a learning here!
Dan

fast_broker

iTrader: (1)

V8Astro,

I would probably modify both cells but you want the cell values to be rather close to avoid the same problem you could have with spark value differences between cells. the ECU just interpolates between the values and you could have a wandering idle from the interpolation problmes between the 30 and 40 cells. ie, the computer goes rich, lean, rich etc as the idle hunts for the best area. I read the same info you did about the spark values being the same and I found it to be true as well in general for idle VE, too.

I guess if your engine runs better with BLM of 135, just leave it that way but I cannot explain it. Only thing I can think of is that your open-loop idle AFR is off a bit and running a BLM of 135 at idle makes things copasetic (sp) when the ECU switches from open to closed loop? Or something to that effect set in a table/value at idle conditions?

LION:

I would guess your BLM's must be close to 128, or your max/min valuese of INT movement were reduced in your PROM so you can't see much swing in them?, if that is possible. It is with BLM, anyway...

[This message has been edited by fast_broker (edited November 01, 2001).]

Grim Reaper

Yes, you are very close and will get the max benefit from lock the BLM. When I first tried locking my BLMs, I was getting initial readings of 110-115. While I was able to correct for it, I also got the occasional SES light - Code 45 O2 sensor rich, because I was locking my BLMs too soon.

After a "burn or two", I was quickly in the same area as you are (120-130s) and able to dial in 128/128. I really don't recommend locking the BLMs until you are at least +/- 10 away from 128 due to the possibility of getting an accidental SES code on a lean/rich O2 sensor. Lock the BLMs reduces the "operating range" of the ECM for fuel correction. If you are already close, then this "narrow range" is not a problem. But if you are excessively rich (or lean), then this decreased "range of correction" can bite you in the butt.

PS: No harm comes to your engine, you just trigger an SES light over a rich/lean O2 sensor which is 1) annoying and 2) skews your results.

prscarf

i notice on a cold start the engine will go into closed loop after several miles and according to the blms i am running rich. when the engine gets to temp i see the blms are very close to 128, is this normal. i do have a 3wire o2 and thought when i changed it from the one wire unit this rich condition would stop. should ve table tuning only be done when the engine is a operating temp?