I am just getting into tuning, I have burnt a couple 512 chips now, playing around getting my idle where I want it, etc. My AEM W/B reads 10.4 at WOT and the car doesn't ping at all, I know theres improvements to be made and I am chomping at the bit, but I thought I would ask, Wheres the best place to start? Course I don't expect it to come together all at once, thanks in advance for the

 

Well, the answer is: it depends. If the 10.4:1 AFR is correct, then it is too rich. A leaner AFR will make more power.

But, at the same time it may not. Why? Because no-one here but you knows the engine/trans/rear/vehicle that you are tuning. For all I know you are at 30 psi of boost with alky, and a 10.4:1 AFR is peachy keen (really!).

I know, I got atti-tude. But one can't ask a broad-brushed question and get a good answer.

Now, lets say you are running N/A, with a stockish engine and drive train. The 10.4 is a bit rich. Although GM did run them this way to prevent engine and cat-con melt down. So lean that area out to 11.5:1 and see how it is. Even leaner (12.6 - 12.8) would be better. But, if there is a cat in the exhaust, you can't/shouldn't do that.

But, to do this you need to be able to trust your WB to give a proper reading. AND, trust your tuning skills to 'feel' that it is all OK.

Once the AFR is in line (plug cuts to verify), then spark timing can be adjusted. This is where even more plug readings are important. And, you need to adjust the fueling as the SA is adjusted.

RBob.

 

Well thank you for not totally busting my chops, sorry I should've been more clear, the car im working with is my '88 Formula 'bird with it's factory 160K TBI 5.0L(running well), automatic swapped out out for a T-5, and the 2.73 rearend swapped for an earlier third gen posi with 3.73's.
It has Hooker 2055 headers and Y pipe, 2.5" catback, missing cat, 180* t-stat, open element, TPI fuel pump, I think thats it. It does have the oddball 1988-only 8063 ECM. With that out of the way, which cells do I make changes to in order to lean this pig out?

 

Well, the answer is: it depends. OK, didn't we already start here?

If in PE mode then set the PE AFR table to the desired AFR. Then adjust the VE tables to meet that AFR. Note that the '8063 ECM has 2 VE tables. The first being a 3D table. Which the 2D VE table is added to.

This makes it a pain, but is tunable.


If in open loop during this time, then need to work on the open loop AFR tables. Then, just as the PE mode, move the VE to obtain the proper (commanded) AFR.

If in closed loop, then there are problems. If at 10.X:1 in closed loop, look at the BLM to see what it thinks.

Note that for open loop tuning, the BLM values need to be at 128. Otherwise, they may be making a correction. Which would need to be taken into account.

RBob.

 

How does VE relate to the AFR? is it higher % = more fuel?

 

Yes. Note that there are some decent threads linked in the Tuning Guide Book sticky up top.

RBob.

 

If in closed loop the VE tables are looked at and A/F is set to close to 'stoich" by BLM feedback. If you invoke PE same lookback occurs to VE tables as well as BLM correction used and then the PE adder is used to achieve the A/F as commanded in PE. The VE fuel tables are not changed except by you when you chose to in a fresh burn.

If I recall the highest VE fuel values you see in .bin are around peak TQ.

edit: I presume you are using NB02 sensor for feedback.