Have lot's of questions about burning chips

[chasmat2316]

This is not for my GN but for my 90 454ss pick up. I have a chip burner, GM pcm definition files, a wide band O2, and scanner. I have a that's kinda close but still needs tweaking in some areas. The motor has lot's of mods. What I need is someone who can walk me through what tables to try to mod, I know what I would like to change, but not sure what to try first? I'm on Long Island New York if anyone can point me in the right direction.

 

[2QUIK6]

Try reading thru here, the 3rd gen guys do tons of prom burning. It is from this website that I learned all of my prom burning / programming skills for my GN / LC2, TPI, TBI, LT1 and LT4 motors.
http://www.thirdgen.org/techboard/diy-prom/

I know there is a good writeup on that site, I think in the "Sticky" on that forum about tuning the fuel and spark a little at a time and what to watch for. Be great if you also have a laptop scan tool to watch for knock and rich/lean BLM #s along with the WBO2....your BLMs could be at their limits but not over and the WBO2 will still tell you the correct AFR is being accomplished.

 

[chasmat2316]

Hi Rob thanx for the info! Yes I have a snapon scanner, but it doesn't show knock retard. I also have an LM-1 wide band to show A/F. The truck is wayy too lean at idle right now in park and I'm not sure what table to start with? I also see it has about 40* timing & think I should take a few out, but not sure from what table? Thanx Charlie

 

[2QUIK6]

Should be a "Main Spark" table that is rpm vs MAP based or rpm/load based.

For fueling, it depends on if it is speed density or MAF controlled fueling.
If MAF, then there should be several MAF tables to adjust...which can be tricky. I haven't done one for a truck exactly like yours, but for all other MAF vehicles, you have to alter the frequency #s in the MAF table which will cause the computer to calculate the air mass either lower or higher for whatever frequency its reading at the different rpms/loads.
So lets say your RICH at IDLE and the MAF shows 8gmps.
Looking in the MAF table at "8" shows a frequency of say 4.65.
To make it leaner, you would make the value at "8" something lower, say 4.25 and then also adjust the adjactent values for 7 and 9 to be just a little lower....do it in very small increments until you are comfortable with the effects of changing it...it can be very time consuming.

Now if its speed density, its much easier..there should be a table called something "Volumetric Efficiency" it should be a combo of rpm, load, MAP based as well. Just go to the cells that correlate to your rpm/load/MAP reading where you need it to be leaner at and lower the number in that cell...or raise the number to make it richer.
I usualy use the BLM number at that load to help determine...for example since perfect is 128, say your BLM is 118.
Then you % off is 118 / 128 = .92 or 92%.
Multiple the number in that cell of the table by 0.92.... If its 80.0 then make it 80.0 * .92 = 73.6 which will lean it out by 8%. That will make the BLM about 128 where you want it.

Hope that helps

 

[chasmat2316]

no mass, this truck is speed density & it idle's in open loop, so no block @ idle. If this was my Buick this would be a snap - it has a FAST B2B! I just don't know my way around the stock ECM format? WOT is kinda close, cruise is good, just needs alot of help with idle & timing! Thanx for any help! Charlie

 

[2QUIK6]

no mass, this truck is speed density & it idle's in open loop, so no block @ idle.

I just don't know my way around the stock ECM format? WOT is kinda close, cruise is good, just needs alot of help with idle & timing! Thanx for any help! Charlie

speed density makes it easier as per last post. Why does it idle in open loop?? Someone already been messing with the program as it should not do that factory...but to change fueling, simply change the vol Eff table mentioned before at the idle rpm cells.

Don't know your way around the ECM format? What ECM file defs do you have and what editor do you have? Something like Tunercat makes it a snap.

For WOT, there should be a table called "Power Enrichment" which is based on rpm and is usually a percentage of fuel to add when in PE mode.

 

[chasmat2316]

if I remember right this truck always idled in open loop when stock.

 

[PowerKraus]

Listen to Rob, he knows what he is talking about....your in good hands.