Help tuning 408

[SRT10KLLR]

I have a 2003 Silverado 2wd that I want to tune using the V2 I just bought. It used to have 5.3L but I replaced it with a bored/stroked 6.0L block. I need help getting it to idle to start with then PT and WOT. I want to be able to tune this thing myself but need to understand what changes to make.

Here are the specs:

408(6.7L) w/8.7cr
P&P 6.0 heads
224/231 .595 .595 LSA 114 cam


BTW, the stock 5.3 tune is what is in the PCM right now and it starts but I have to keep my foot on the pedal or it dies.

[ScarabEpic22]

Can you post up the stock tune? I dont know if I can help, but I know others will want it posted anyway. Have you looked for a 6L tune in the repository that you can modify the cylinder size in?

[SRT10KLLR]

I did check the repository and the 5.3 tune there was identical to my stock tune except for the top speed limit(mine was 109 vs 98). I also looked at the 6.0 stock tune and a 4.8 tune. What I thought was strange was that the timing table was not proportional to engine size. I thought the timing would either go up from the 4.8 to the 5.3 and then to the 6.0 or down.

I did do a log but could not see anything out of the ordinary but it could be that I just don't know what to look for yet. I had to have my foot on the gas while doing it otherwise the engine would shut off.

BTW, I noticed that the 4.8, 5.3 & 6.0 from the repository all used the same size injectors.

Thanks, any help would be appreciated. I am new to EFI but want to learn as much as possible.

[ScarabEpic22]

Im not talking about spark tables or injectors, Im talking about cylinder expected airmass. Look at table B0104, the 5.3 tune is 666, the 6.0 tune is 746. Yours should be even higher as its a 6.7L.

[SRT10KLLR]

The B0104 was 40.64 in my tune so I changed it to 51.02 for my 408. What else do I need to change?

Below is a copy of my tune with the only change so far being the B0104 cell.

[Bruce Melton]

What TB is on it now?

[SRT10KLLR]

Stock. I think it is a 78 or 80 mm.

[SRT10KLLR]

Any other suggestions/advice? I could use all the help out there.

[RonC]

Any other suggestions/advice? I could use all the help out there.

One thing I see is your VE table seems to be off and that would make it very lean. I looked at VE % on a stock 6.0L it peaks at 104% and your VE table peaks at 75%. I would suggest starting with a stock 6.0L VE table and tune it from there. It looks like you still have the stock injectors and it should run ok on the low end thru upper midrange with them but you will probably need 37lb to 42lb injectors for full WOT power. Hope this helps.

Ron

[joecar]

You need to either richen the last 3 columns of CFOL B3605 and /or
reduce the PE Enable B3616 throttle position (90% is too high),
otherwise you'll be too lean at load/WOT.

Are you tuning with a wideband...?