How much tuning do I need to do
Thread Starter
Teching In
Joined: Sep 2017
Posts: 34
Likes: 4
From: Edinboro, PA
How much tuning do I need to do So I am curious how much my tune is going to be altered with a few of these mods. Here is what I have as a starting point.
LQ4 with 36lb injectors and an LS1 intake
The mods I’m making:
243 heads w/ PAC 1219 springs
Sloppy Stage 3 cam 238/242, 595"/.595", 112 LSA
Atomic MSD Intake with 102mm TB (DBC)
I have HPTUNERS already. Just curious how much it’ll be off. Will I need to do a whole new tune just to get driving to a dyno?
Any help is greatly appreciated.
LQ4 with 36lb injectors and an LS1 intake
The mods I’m making:
243 heads w/ PAC 1219 springs
Sloppy Stage 3 cam 238/242, 595"/.595", 112 LSA
Atomic MSD Intake with 102mm TB (DBC)
I have HPTUNERS already. Just curious how much it’ll be off. Will I need to do a whole new tune just to get driving to a dyno?
Any help is greatly appreciated.
I'm pretty new at tuning myself, so please take this for what it's worth. If you have HPTuners, For adding a cam and 799 heads I believe you can just add a flat percent across your VE tables to start (look for some tuning docs for the exact number, for some reason I'm thinking 15% but I may be way off), and in my largely uneducated opinion I think the VE should be close enough for normal driving that fuel trims will be able to compensate the remaining diffference and can get you to a tuner if you drive it easy. It's the IDLE that's probably going to be a headache for you. Do you think you would be able to use your HPTuners to at least get the idling to an acceptable level? I used Russ K Idle Config in my HPTuners on my LQ4 when I added cam and 799 heads and it worked wonders. It's been a few years but that's what I think I did.
Last edited by mk3cn4; Jul 31, 2021 at 10:22 AM.
Thread Starter
Teching In
Joined: Sep 2017
Posts: 34
Likes: 4
From: Edinboro, PA
Will, I can appreciate you asking, but there's no real answer.
To begin, it's going to be rich down low and lean up top, that's just how it works with the mods you made. The injector data will need to be corrected, the idle airflow will need work, the idle tip in and timing will all need work.
Can you drive it? Maybe. Would I, No.
Tuning is a steep learning curve if you don't understand the basics of the mechanics. The camshaft changed the efficiency of the engine. It's now less efficient down low, more efficient up top. The heads also play a part in the airflow, and combustion compression. You went from around a 9.5:1 to around a 10.5:1 ish setup. That's just 2 parts, not to mention the air intake track, filter, exhaust ECT. Your looking to have say less than 3% error, you probably have upwards of 20 in places now if I were to guess. The ecm just can't correct for that.
To begin, it's going to be rich down low and lean up top, that's just how it works with the mods you made. The injector data will need to be corrected, the idle airflow will need work, the idle tip in and timing will all need work.
Can you drive it? Maybe. Would I, No.
Tuning is a steep learning curve if you don't understand the basics of the mechanics. The camshaft changed the efficiency of the engine. It's now less efficient down low, more efficient up top. The heads also play a part in the airflow, and combustion compression. You went from around a 9.5:1 to around a 10.5:1 ish setup. That's just 2 parts, not to mention the air intake track, filter, exhaust ECT. Your looking to have say less than 3% error, you probably have upwards of 20 in places now if I were to guess. The ecm just can't correct for that.
