New to HPT and need help getting started. Vortec 350 stroker hard to start when cold.

[oldeerslayer]

A couple years ago I put a 377 Vortec in my 98 ZR2. It's the same stroker kit as a 383. w/o the .030 overbore. The engine is totally stock. As is the drivetrain. I'm running a 98 Tahoe 350 Vortec factory tune in the 98 Black Box PCM.

I just bought HP Tuners and to be honest I'm totally clueless as to how to actually start tuning.

My problem is that the 377 is hard starting when cold. Since I've increased the displacement 8% w/o changing the fueling in open loop I think the problem is that it's not getting enough fuel for cold starts.

Can anyone with HPT explain how I go about enriching the mixture for cold starts? My old brain seems to think 8% more fuel should fix the issue.

Once in closed loop it runs fine.

[kevin87turbot]

It may take a few steps to get it dialed in, but it's not too complicated.
The first step is to update your cylinder vol. The new vol will be 47.125.
On the 98 model, you'll have Prime Pulse Mass and First Pulse Mass numbers. I would mult both by 1.08. That should get you in the ballpark

You'll likely have to update the VE table as well, but for a stock cammed stroker, it should be in the ballpark.

[oldeerslayer]

That's the info I was looking for. At least now I know where to start. Thank you.

It may take a few steps to get it dialed in, but it's not too complicated.
The first step is to update your cylinder vol. The new vol will be 47.125.
On the 98 model, you'll have Prime Pulse Mass and First Pulse Mass numbers. I would mult both by 1.08. That should get you in the ballpark

You'll likely have to update the VE table as well, but for a stock cammed stroker, it should be in the ballpark.