LS1 Always dies at initially startup

[wilhit10]

I have a 1996 BMW M3 LS1 swap and have always had issues with it staying running at startup. It immediately fires, then dies. I can always get it going with adding more gas pedal, and it will eventually will idle. About 1/2 the time the car stalls at stop lights. It will even die occasionlly when I put in the clutch pedal. Any help would be greatly appreciated. Attached is a small log of a startup and my tune. Car was tuned by Back Street Performance and then Steven Williams.

1999 LS1- Stock Long Block
*FlowTech Induction Cam Kit
*Streetsweeper HT Cam 228/232 111 .612 .600
*.650 Lift Dual Valve Springs
LS6 Intake Manifold
Stock Ported Throttle Body

[dermotw]

Assuming its a manual...(there are no values in the p/n part of the idle airflow table)

The idle airflow, throttle follower, and friction airflow/startup airflow is where I'd be looking...

kr d.

[gearhead927]

I know absolutely nothing and am struggling tuning my own car but I noticed on your data log when the rpm are highest during the start B1 injectors are maxed out and B2 shows nothing. Maybe this is normal, like I said I am a noob.

[wilhit10]

Anyone else have an idea?

[dermotw]

The spark overspeed and underspeed tables often need adjusting with a cam, they are too aggressive, without a log of idle, hard to say, but its typical to change them (and yours are standard). Also, your idle spark advance is higher than it needs to be (not a good thing) and its not similar between the various tables (hi oct/low oct/idle drive/idle park) better if in the idle/just above idle areas these are either the same or very close.

You Idle startup airflow delay is 50 revs, more usual would be 5, also your startup airflow decay is at 0, meaning there isn't any, more usual would be .100 or so.

Your friction & startup airflows maybe low, certainly they are lower than mine (see my sig for my mods). Yr base running airflow at idle is <much> higher than mine (more than double).