caboboy

Hi all, I'm an extreme noob getting ready to burn my first chip when my Burn2 gets here next week, I'm pretty excited! Man this has been a steep curve, but I think I have a handle on adjusting my calibrations in the MAF tables to achieve a 128 BLM value +/-. My question is this: I'm in pretty good shape in most places except for steady cruise, which shows a rich value of 118-116 and this always seems to show up in BLM Cell 10 no matter what steady cruise speed I'm at........15mph, 25mph, 35mph, etc. Should I be trying to make a global adjustment of some sort in BLM Cell 10, and if so how would I do this? Or should I be adjusting these values in MAF tables 2 and 3 which is where most of them are located? And if I do that, should I smooth out the adjoining cells? For example, if I decrease my 50.25 flow value by 8% (in Excel row 1012 attached), should I be also make an adjustment in the next cell of table 3 to create less of a gap so it doesn't hiccup when I pass thru these points? I'm an old time gearhead from the 50s and 60s and understand most of the principles, but this computer stuff is pretty darn new to me.

The car is an 87 Vette with an A4 & highly modified 421CID.......Thanks!

Orr89RocZ

iTrader: (20)

In situations like this, I have always smoothed the adjacent cells. Maybe not as much as the change I made to the target cell but alittle change to help smooth the transition. Reason is you rarely hit the exact value in the MAF table but are usually in between values.

Like 50.25 g/s falls between entries 48.63 adn 52.2 in MAF table 3. So you would have to lower both entries alittle bit in order to also change 50.25. The ecm interpolates between values.

Looking at your values, your INT is close to 128 and BLM is just a touch lower. Getting a perfect 128/128 is rarely going to happen. I'd be happy where you are at. I'd try lower those entries around 1% and see where it goes. You are not too far away from 128 so I'd go in very small increments.

Also you could try just adjusting timing. Give it a degree or 2 more advance in those rpms/LV8's and you may see BLM's work out to 120's. I'd try that before adjusting the fueling.

caboboy

I attached another screenshot of a 65mph cruise & labeled the headings, maybe the info will be easier to read. I never thought about the timing angle though......very interesting. I think I must have tunnel vision because this is all so new to me. It makes a lot of sense though, thanks! This 116-118 BLM lean condition seems to be directly related to that Cell 10 & that's a function of load as I understand it. I hadn't planned on getting into the advance table until I played with the MAF readings, but that's only because it's what I've read about tuning here on 3rd gen. I've always thought I'd ultimately have some room in the spark table, as I don't get any knock counts to speak of. Here's a pic of my current spark table as well, thanks for your input!!

Orr89RocZ

iTrader: (20)

Give it alot more spark and it should come around. Alot of guys run 34-40 deg in those ranges and you have 28 or so. Abit conservative. Try giving it some more and see what it does.

tequilaboy

Cell 10 is between 22 and 34 gm/sec airflow and between 1200 and 2000 rpm with typical boundary settings.

If you are running rich in cell 10 as evidenced by your low blm values, you would want to reduce the MAF flow in the voltage range that accompanies the target air flow region (22-34 gm/sec). Making changes at 50 gm/sec will have no effect on cell 10.

Leaning out this flow range will also affect cells 8,9, and 11. If these cell's blm values end up going much leaner than cell 10's blm after the changes, then you need to add more low pulse width offset to compensate.

Another possibility is that you have too much vbatt offset for your injectors (which is likely), but this will tend to influence all cells.

caboboy

Tequilaboy (I dig that screen name! ) I'm lost on this..........keep in mind I'm brand new into tuning. Where can I find vbatt in T/P so I can start reading up on it to get an understanding? I'm using ARAP & 6E and I can't find anything. Is this an abbreviation?

Orr89RocZ

iTrader: (20)

The table he is refering to (I think) is the injector base pulse width correction vs battery voltage.

Those are in usec units, increase them to add more fuel for the given battery voltage. Decrease for less fuel.

Generally there is more fuel added when the voltage drops. If you ever watch a wideband air fuel gauge and the battery voltage at the same time, you can see when battery voltage dips much below 12-13 volts it may start to go pretty lean. You have to tweak that table in the lower voltage areas to ensure you keep same air fuel when battery drops. Not a problem generally when you have a good alternator and fresh battery. But one day say the battery starts to die or the alternator fails, and battery voltage drops, you need that compensation.

For your rich BLM's, you could try to take out 50 usec or so in the 14.4 and 12.8 voltage cells and see what happens. Its a much more fine adjustment than MAF sensor i do believe.

caboboy

Ahh I just found it, thanks for the clue! I'm hiding from my boss here at work, but snuck a look at TP & found something pretty interesting...............my bin values in that table vary quite a bit from the ARAP bin. This might bear some further investigation when I get home. Dang work keeps getting in the way of the important stuff.......................

caboboy

Success!!!

OK, maybe moderate success; but at least I'm moving in the right direction. I created a separate spreadsheet that contained a copy 'n paste of all my rich areas & I was able to concentrate on the pattern. I tweaked about 20 or more points in the timing table & viola.............all my 116/118 BLMs are now 124 & 120. I still have a very few 118s left, but I was able to grasp the concept & had some terrific results burning my very first chip! Thanks for the help Orr89RocZ, your timing suggestion was right on! The car feels like it's got a lot better tip in with the new advance too!

Now it's time for some more minor adjustments to target the 118s & 120s & then I get to learn about vbatt & offsets..........this is sooooo much easier than recurving a distributor on the Sun Machine

Thanx guys!!!!!!