5.3 cam tune help

[Joshloc31441]

I have a 05 5.3 in a 77 impala with a ls6 intake,shorty headers and a 223/232 614/599 with 111lsa cam.the whole tune is off and i could really use help to get it idling decent.ill try to post the tune and logs that i have so far asap..thx allot for any help you can give me

[Ben E]

Hey Josh, I'm still a newbie myself but sort of figured out some stuff and I'll try to relay that information to ya. My knowledge is fairly limited and all derived from my 1999 GMC Sierra 1500 with a 5.3l V8 Automatic that is fairly stock. I'm still trying to figure out my own stuff as well.

Depending on what equipment you're working on this will all be different. The information I am giving you will help if used from a stock file, which I'm assuming you're using an 2005 file(I've not looked at one yet). All of my information will also be different for your application, larger cams are harder to idle as well. If you can you should figure out your cam overlap. Negative overlap is better for idle, and positive overlap is more difficult to get engines to idle.

Before we even start make sure your fuel injector values are set up correctly for what is inside the engine or none of the changes to air or fuel will be correct.

Now, will the car idle without you pressing the accelerator pedal? If not there is a few things you can change to get it to try and idle. Get into the [Engine->Idle->RPM] tab, then into Target Idle Speed parameter and set the RPM to something high like 750-900 RPM or whatever helps keeping it from dying. Then go into [Engine->Idle->Airflow] tab, find the Base Running Airflow parameter and add 1-2 g/s of air to the 104*+ columns. In the same tab go into the Startup Airflow Initial parameter and add 2 g/s of air in each column. Depending on how hard the car is to start when warm or even cold, you could add more air to the base running airflow or startup airflow initial parameters. Otherwise you can also go into the Startup Airflow Decay parameter and add 25 to 50 RPM delay to each column. This will all help to get the car to idle better and start easier. There are more specific tables that can be changed to fine tune idle, which I'm trying to figure out.

Next, go into the [Engine->Airflow->General] tab, and go into the Main VE Primary parameter. For the 400 RPM column multiply it by 60%, 800 RPM column multiply it by 80%, and lastly for the 1,200 RPM column multiply it by 90%. This will remove some fuel as larger cams are less efficient in low RPM operation. Now my truck doesn't have an electronic throttle body and I'm assuming the 05 engine has one, so there will be many different tables you'll have to adjust for correct operation. In fueling and airflow.

Next, go into the [Engine->Spark->Advance] tab, and go into the Idle Spark Advance In Drive and In Park parameters. The goal is to try and find the highest spark timing that gives you the highest MAP value. More spark generally gives a higher MAP value, don't go overboard as spark knock can happen if timing is too advanced. If you keep going up in timing and the MAP value does't change, go back to the last value that increased the MAP value. My truck liked an extra 2 degrees, you probably can add 3-4 degrees in the 0 to 1,200 RPM columns, AND 0.08 to 0.28 g/cyl rows. Make sure the timing in those parameters are the same for the In Drive and In Park tables for idle transition smoothness. Lastly, go into the Main Spark Advance High Octane and Low Octane tables and adjust the idle values too. Other tuners suggest making the idle values the same as the in drive/in park tables but I personally just added my desired spark to the lowest values in those areas to bring it up to what was set in the in drive/in park tables.

There are a lot of things I didn't cover as they are specific details and even things I don't know how they work. You'll have to test them out and go slowly and change one thing at a time to make sure you didn't screw anything up by changing it. Depending on how your cam and headers work, your front O2 sensors may be unhappy and run you rich at idle and that's something else you'll have to look into. I went over the main tables that will get your car to idle well, and it has for me with some other fine detail tweaks. One last note with the idle RPM, the goal is to set it as low as you can without losing a stable idle. To do that you may have to adjust the airflow/fuel/spark tables once again to stabilize the idle again.

If you are idling well, and you blip the throttle and you overshoot the target RPM and the car dies or goes back and forth try adding more idle air. If the idle hangs either after bliping the throttle in idle, or coming to a stop, you either have too much idle air, or too much idle timing(or timing in the main spark advanced tables) and will have to adjust those values.

Hopefully everything I've said made sense and helps you out.

[Reddmann]

Do you think you could help me I have a stage 4 tsp 223/226 .600/600 111Lsa and a 109 intake center line and tbss intake swap still currently using my factory 3 bolt throttle body with an adapter. I have to un plug my vacuum line from my head in order to drive and if I don?t then it dies as soon as I let off the gas and also waiting to put 36 pound/hr flex fuel injectors in and I have the laptop and everything to do the tuning just needing help.

[ryan_axberg]

this is a post from years ago, he probably won't answer. there is a lot to learn about tuning, it will take a while to get stuff figured out if you want to do it on your own. Or you could take it somewhere and have it tuned, would probably be worth it if you have a good tuner near by