Mutha Thumpa Cam Help

[jmsmotorsport]

am trying to get a rebuilt ls1 running a Mutha Thumpa cam idling and running properly. Will use RAFPN etc but I cant really get it to idle so I can apply it. I know everyone says don't worry about AFR at idle but its showing 12.5ish at idle an 22 degrees if I use DVT and lean it out idle improves so I know its to rich. I've been reducing my VE in the idle area to fix this but how low will the VE end up? and will I end up with a very low VE and then a big step up as rpm increases?

Would anyone have a base tune that I could look at to make sure I'm heading in the right direction.

[statesman]

Big fuel injectors?

[jmsmotorsport]

Big fuel injectors?

Nah mate just factory ones.

[statesman]

Can you give a list of mods and post your tune file and a log of your idle.

[jmsmotorsport]

No mods list it’s literally a factory rebuilt spec ls1 with a mutha thumps cam.

[statesman]

You're running that cam with stock valve springs?

[jmsmotorsport]

Plus supporting mods in the valvetrain for cam.

[statesman]

Okay. Your VE will be lower at idle with that cam. How low has it gone so far?

[jmsmotorsport]

2175021751

[statesman]

I'll have a look through your tune and see what I can find.

[jmsmotorsport]

Cheers it’s pretty basic just trying to get it so can start dialing in the VE

[statesman]

Your tune file has 'out of range' tables... you need to fix those.

Your minimum fueling is a bit high... it shouldn't affect idle but it will give you a wickedly rich decel.

Your tune file appears to be set for closed loop, but your narrowband O2 sensor hangs around 450mv constantly (probably a dead O2 sensor).

I would suggest switching to open loop for initial tuning... adjust commanded fueling table to stoich in the idle area before you start to tune.

[jmsmotorsport]

What are the out of range tables?

Wont DFCO control fuel decal when its enabled?

Have fixed the CL OL settings, Missed that one.

Has No 02's plugged in at the moment.

Is that in B3647?

[statesman]

Out of range tables...
{A0014}
{A0015}
{A0008}

The amount of rich decel will depend on how aggressive your DFCO is set.... I'd still lower minimum fueling.

Not having an O2 sensor explains why it's not working.

Yes, {B3647} is your commanded fueling.

[jmsmotorsport]

Fixed those out of range tables they didn’t come up when I searched out of range probably because there efi custom tables. Can you give me the Table number for min fueling?

[statesman]

{B4003} & {B4004}

If you still get a rich decel after lowering those, you'll need to get the {B9021} cax file... if there's one available for your OS.