Default Just swapped in an LSA engine, having some driveability issues.

[Kamaro]

I sold my 416 engine and bought a bone stock LSA, I rebuilt the engine with new .010 oversized pistons and added a LS9 camshaft and a 2.55 upper pulley, since its swapped in a '71 Firebird, it already has a LT headers and cold-air intake. I ordered a stock CTS-V PCM out of a 2009 Caddy so I was expecting it to start right up and drive nice since its not a heavily modified engine but otherwise it starting out very rich then it will lean out in a minute or two then it will go back the rich status again, then it would die when I ever I coast down. I attached a HP Tuners tune and log (the log starts from a cold startup to a short drive where it died a few times on me). Can someone have a look and tell me whats happening?

[5FDP]

Think about it a little though, the engine calibration is designed around a stock engine. Putting in oversized pistons means the engine is now larger than before and the different camshaft, so the whole entire airflow model is incorrect.

The log shows it's trying to yank 25% worth a fuel almost all the time so it for sure needs a lot of attention.

A question about the swap. What fuel pressure are you running? Is it a solid pressure or is it boost referenced?

[Kamaro]

Think about it a little though, the engine calibration is designed around a stock engine. Putting in oversized pistons means the engine is now larger than before and the different camshaft, so the whole entire airflow model is incorrect.

The log shows it's trying to yank 25% worth a fuel almost all the time so it for sure needs a lot of attention.

A question about the swap. What fuel pressure are you running? Is it a solid pressure or is it boost referenced?

I have noticed that its trying to trim off the fuel all the time, I'm puzzled about that because having larger cam and more boost should equal to more air, so I expect it to more lean, not more rich, but again, what do I know!

The fuel system is so basic, a Walbro 255 lbs fuel pump through a C5 regulator/filter without any boost-reference. The fuel pressure at the rail is a constant 60 psi. I have another Walbro 400 lbs pump and an aeromotive vacuum/boost referenced regulator which I will install soon.

[07GTS]

put the walbro in with the referenced reg and then fix up the fueling, if u get it all good now then swap it over u will basicly have to start again, u have to setup the injectors flow/offsets different depending if u are referenced reg or set pressure