I just started my rebuilt 385LT1 with cc306 camshaft and the following mods:

52mm BBK TB
30# FMS injectors
Stock Fuel Pump
Long Tube headers
Ported LT1 heads
Ported MAF
Eagle forged rotating assembly with -16 dish pistons.
Manual Transmission/3.54 rear ratio

I still have my old tune.What exactly need to be changed in the the new tune. Will it make a big difference.

Also, my check engine light is on and the fan is on all the time. I used EZ link to scan for error codes but found no errors.

Any help.

 

Do you have tunercat?

I've been working on tuning my car for quite a while with tunercat and the cc306. With the bigger injectors you'll need to update that in the tunercat constants section. Since you have bigger injectors, I'm not sure if you'll still have to increase the fuel pressure or not. I had to put on a new pressure regulator for that.

Then I tuned for idle. Can't remember the exact procedure but I bumped the idle up to around 1k rpm. Then increased the vaccume a little by advancing the timing (if I remember right). If I had access to my laptop I could tell you (unfortunately it's in storage w/ my car right now).

With it idling smoothly I took the mass air flow tables and leaned them out down low. Then increased them up high. In order to know the exact areas to tweek I did TONS of data logging and mine still isn't even close to perfect. It's a pain. The stock timing seemed to be pretty good for me. Messing with it only made problems worse so I left it at stock.

Then I made some other minor adjustments... Fans, eleminated egr warning etc.

Hopefully this helps!!

 

Never mind, I had a mail order tune from Bryan at Pcmforless and it runs perfect.