First Post: Gen 3 LS364 2006 Yukon XL-brand new crate engine

[CB Staton]

Hello! I have been watching videos, reading the forum and trying to learn as much as possible as I get ready to fire up the family hauler for the first time since installing a brand new crate engine from GM Performance. I know I need the vehicle tuned for the new engine and after doing some research, I think I got this. Although reading some of the horror stories in the forums has me a little scared.

Here is what I have...

GM Performance LS364
Holley Low ram intake with 36lb injectors
Stock throttle body with adapter
Pacesetter long tube headers
K & N cold air that was on the truck previously
Stock sensors

No exhaust hooked up yet- will do it as soon as the truck is up and running. I will add high flow cats and new magnaflow or flowmaster muffler.


The differences between the factory engine and this crate engine are...

Old Motor_____________New motor
Compression 9.4 ___________ 10.3
Cam lift .467/.479 ______.550/.550
duration 196/207 ________204/218
HP 330 _____________452

I don't want to be lean on initial start up and break in of the engine. I just want to be "safe" for that period of break in. The cam is close to the stock cam and I am hoping I won't need too much timing adjustments in the beginning. So my question is...

Do I just need to change the injector size info in Hp tuners? or do I need to richen the entire fuel map as well? I know that I will disable the post cat o2 sensors and put the computer into open loop to get things running. I have also purchased an AEM wideband to go with the recently purchased Hp tuner pro that I will install as well. Any suggestion to basic configurations before the key gets turned for the first time would be greatly appreciated!

[mbray01]

disable dynamic airflow, let it run maf only for start up
up idle rpm to 750, add .7lb/min across the board on idle airflow,
input correct injector data, make sure you have enough exhaust past the oxygen sensor, or it will start adding tons of fuel.

this will get you up and running to to over fluids and get final checks

[CB Staton]

Thanks for the input, Michael!

[kingtal0n]

You want it lean at idle and cruise to keep from carboning up the plugs, pistons, cc, etc...

Lean at idle and cruise is the a/f ratio 14.8 to 15.2:1

Leaner engine = cleaner engine

The only time you want rich is when the engine is under significant load, like wide open throttle or heavy towing.

If you startup the engine very rich and run it rich all the time fuel will pollute the engine oil and degrade the oil causing excess wear and tear on the engine.
Being rich all the time also coats every part with carbon soot which may become tar-like sticky or hard diamond-like depending where it collects and what the temp and pressure there is.

You should become familiar with the scanner controls as they can be used to effectively start and idle an engine without any tuning by simply adjusting the commanded a/f ratio on the fuel tab, this will temporarily allow you to run safely at any a/f ratio and idle the engine for break in or whatever while you figure out how to actually tune it.

Heres a list of air fuel ratios to use when tuning the engine at various load points,
this is for typical street strip vehicles 3000lbs to 4000lbs ranges
https://forum.hptuners.com/showthrea...l=1#post678778

[CB Staton]

Perfect! Thanks as well!