I have recently been refining the tune of my 84 Xfire using Bruce's final answer bin and referencing Bob Rauschers IAC article. I have just about all of the cal tuned to give me 125-128 on the INT(BLM's locked) in every rpm range except 1600rpm. My Vette has the 4+3 trans and has been converted to using a 7747ECM.
In direct, the MAP will register between 40-50kPa with a INT of 125-130. This corresponds to 39mph at 1600rpm. However, in OD,
with MAP registering between 45-55kPa, the INT will jump to 144.
This corresponds to 58mph at 1600rpm.
Some further background, I modified the intial fuel tables so I had a consistent VE of 10.1 on adder Table #2 top to bottom. This was based on some previous reading on had done on this forum concerning tuning #1 Table. Moving the VE primarily to Table #1 gave a more "accurate" picture of the true fuel map for the motor. At least that was the theory. I also bumped PE to 75% TPS from stock 60% for tuning purposes.
In order to remedy this situation, I have been adding fuel to the 50 and 60 kPa cells for 1600rpm but this is resulting in a fuel map where some 1600rpm cells have a higher VE than the corresponding 2000rpm cells. I have also tried adding fuel through the #2 table attempting to avoid a "funky" looking fuel map.

My question is: :hail:
1. Does it matter that' it's funky looking as long as it works?
2. If it does matter, how would you recommend I convert back to
a Table #2 that uses more standard VE values like 39.1?
Is the relationship between 1 and 2 purely additive or is it
something more exotic than that?

Motor has the following:
CompCams HR 212/218@.050" .488"/.495" lift 1.6/1.5 rockers
TFS 23d Heads
Modified Xfire manifold
2.13" TB's
TPIS Headers
TB's are parallel plumbed with 80# injectors running 10.25 psi

 

I can only help you out on question '1'.

Yes it does matter. The VE chart should be a basic representation of the VE of your engine. I got smacked around a while ago (and rightfully so) for posting a map that worked for me, but appeared to be wuite weird. I had lots of flat spots and dips.

In a nutshell, I had problems with my canister purge. At any CCP DC, I went to 108 BLM and I tried to negate this with VE map manipulation.

Needless to say, I finally found my problem and my VE map looks more like a VE table would really look like for my engine. A basic VE curve is smooth. That is the key point. Even if it is high in some areas, it should be a smooth transition.

Good luck, -Matt-

 

What's rule #1?.
Hmmm lemme look,
ahhh, here it is,
GIVE THE ENGINE WHAT IT WANTS.
Ya, I remember that now LOL

Try it,
play with the extender a little and see what happens.

Now what makes you thing that it's entirely fuel related?.
Have you tried moving the timing there?.
Too advanced or retarded of timing can generate a false O2 reading.

And there is always some sort of reversion, how it manifests itself can be a mystery at times.

test, test test

 

Bruce,

As always you are correct. I have been playing with it today and have improved it considerably. I did as you suggested and adjusted the timing a bit as well. It started to narrow down as more of a tip in problem and now the MAP makes much more sense. I originally had been trying to tune with the BLM's unlocked before I had it down solid. Really didn't work out so I went back to locking them and using INT. Much easier, at least for me. In combination with tweaks to the IAC parameters, the idle is really smooth at 800rpm. It also returns to idle quickly when decelerating to a stop.
And now the INT's are averaging 125-128. Really mellow exhaust sound and the motor is quiet at cruise.

 

Kewl,
speaking of quiet,
I've been doing some ultra low cruise timing chips for the GN, and it's beginning to sound like a N/A 3.8L Regal. Just a lil extra fuel.
Howz less then 30 at cruise sound?.
Cooler running to boot.

 

Bruce,

I have found that also. If the BLM's are slightly on the rich side it seems to quiet the motor down. After tuning for the last 1 1/2 years, I have become aware of the "noise" coming from a motor that may be running a bit lean. Richen it up a tad and the "hashy" sounds go away leaving you with just a mellow exhaust note. It gives the impression that the motor is operating with balanced cylinders firing with equal strength and therefore cancelling each other out. That ain't bad from a N/A motor using TPIS headers and Flowmasters. That is of course until you "get on it".

 

Ya, but, the assimulation won't be fully complete til you cross to the Dark Side.........

 

Bruce,

I know that although your GN "appears" to be still "under construction", it is a FULLY OPERATIONAL BATTLESTATION.
The Emperor has his own definition of a "sleeper".:hail:
Many Bathans died to bring us this information.

 

OMG 2 Funny!

 

It's always in a state of morphing.
Waitilya se the next ignition upgrade.......