Large cam (btr LS3 stage 3) tuning, need some help please.

[bstuder11]

So I installed a BTR LS3 stage 3 cam in my G8 GT and obviously I need to make some changes with my tune but I have not done any tuning for this kind of swap. Most of my tuning has been on forced induction engines for fuel and spark or simple torque management kind of things. When you first go start it up and it’s cold out it will fire right up And idle fine but then after you drive it a little while it will die when you come to a stop so you have to Two foot it and if it does die it’s very hard to start; it literally turns over really hard like the battery’s low almost even though it’s not and has a brand new battery and it doesn’t want to stay running. If you come to a stop put it in park and slowly little off on the Excelerator you can eventually get it to sit there and idol on its own but like I said I know this is common and I expect to have these issues going to such a big cam but I could really use some help on what parameters I need to adjust and how I need to go about adjusting them. If someone happens to have a tune for the set up since it’s very popular for this car or this engine even and would not mind sharing it with me I would also greatly appreciate that obviously. I would however like to learn from this also so I’m not just looking for somebody else’s work. I’m also pretty used to turning speed density non-MAF and non-02 Stuff anymore with all of the forced induction stuff that I do so I know there’s probably some airflow things I need to adjust for the math and I’m getting codes for the map sensor even so again any help you guys might have from experience with this would be greatly appreciated

[joecar]

Head/cam swaps usually start up right away, but require tuning to help them run correctly.

Do these steps:
- make sure rail pressure is good,
- correct you VE table using speed-density (i.e with MAF disabled),
- put MAF back on and make sure MAF table is correct (with VE disabled), correct if necessary,
- do some idle tuning (will require ambient temperature variations)(this will take the longest).


With idle tuning, cam overlap will allow unburnt fuel/oxygen into exhaust at idle (and low throttle), this will register on wideband as a lean condition, this might trick you into adding more fuel which just makes it worse, so just be aware of this.

[bstuder11]

Thanks Joecar! Seems like I can always count on you to help me out over the years LOL. My wideband ratio seem like they are pretty good and it only starts up good and run a like you were saying when it’s really cold otherwise it’s like The battery is almost dead when trying to crank it over.. I want to say that there’s probably some anticipated airflow values or something along those lines that need to be changed but I’m so used to the LS1b’s I am having a heckuva time figuring out how to do much of anything to be honest. I would say that since it starts up good and runs good when it’s cold I probably also need to be looking at some parameters that deal with IAT and ECT so I was kind of hoping as common as this model is on these cars someone had done exactly what I’m dealing with maybe LOL

[joecar]

More info to read and try out:
Idle-Tuning-Helpful-Info-Inside (https://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside)
RAFIG-PDF-Includes-all-of-SSpdmon-idle-info (https://forum.efilive.com/showthread.php?26435-RAFIG-PDF-Includes-all-of-SSpdmon-idle-info) <-- contains pdf of thread above it

[bstuder11]

I wish this was in my e38 ecm cause hard starts are my main problem at this point 21979