Well the good news is that the 383 is up and running. Bad news is, it's got split blm's, and it's running on the lean side of life (thank god for o2 sensors and computers that learn).

Anyhow, what do you guys think I should go after first. The split BLM issue or the general leanness? It's not too bad, nothing over 140 BLM, put it that way. The split is about 18 or so.

It's a 383, 9.5:1, LT4 Stage 2 MTI Heads, Matched intake, CC305, 1 5/8th's headers, 24# SVO's and a 52mm BBK/Edelbrock TB.

 

Get your idle figured out and get rid of the split first.
The blm you describe is OK for now.
What injector constant and fuel pressure are you running?

 

help me out guys....what's split blms??? Sorry learning here.

 

25.438 is the constant I'm using, with the stock offsets. I'll drop in Christian Miller's recommended offsets (http://cmillard.freeservers.com/Z28/...%20offsets.htm) and see what that does. Stock FP because I don't have an adjustable regulator.


Oh I forgot to mention, those are brand new AC Delco O2 Sensors on the car...

 

S.J.S split BLM's are where your Block Learn Multiplier (BLM) numbers are split across a gap.

Ie: 128 being what the PCM is trying to achieve. Let's say you have a 124 Left BLM, and a 140 Right BLM.

The different readings cause problems for the PCM. The one on the Left is telling the PCM to take out Fuel, while the one on the right is telling the PCM to add fuel. It puts it in handcuff mode and pretty much leaves it as is. Which probably isn't correct.

This creates problems at the drag strip because when you're sitting at the line at idle, and the BLM's are like they are above the PCM will try to figure out how much fuel to add as the base WOT fuel settings. It'll pick the 140 BLM (since the system is trying to guarantee that you don't go lean) which will add in a ton of fuel. It will then add/subtract fuel to that base BLM based on your PE table settings and you'll be running rich all the way down the track.

Or at least this is the way I understand the problem. I may be off my rocker for all I know.

 

Hey How would I fix my idle anyway? Bump the timing? The IAC count is decent around 65 right now.

 

Low velocity air could also be your issue, you could try bringing your iac's down to 24-35, open your tbset screw a turn.

I'm tuning a cc306 383, i had some issues down low..
In the end i went with a new 58mm holley tb that helped alot.

Set your on idle timing to 36-44 see what it likes mine seems to eat timing on idle.

Good luck mine cost me a tank of gas in the garage..

 

I did a quick write up on idle tuning...might want to read that here. It's right on the front page at the top. There is also some stuff on ECM constants there. Some of that might help out too.
If that doesn't answer your questions, let me know.