2016 sierra 5.3 Help with long tube headers no cats.

Hi all,
Tuning a 2016 sierra 5.3, BTR stg 2 cam with 4 deg limiter, speed engineering long tube headers no cats, 6.2 factory intake and matching throttle body and AEM cold air intake. Rear o2s not fitted currently. Have set up a decent base tune, starts runs and idles great. Still needs maf, vve, timing to be tuned.
Two issues i believe i have are, what setting need to be adjusted for no cats? I have COT disabled, but i believe there is a cat warm up (Light off) that happens on cold starts, have searched through the tune file and cant find what im looking for. It will occasionally back fire out the exhaust during the first 30 seconds of running at idle which i suspect is the cat light off?.

The other issue is what tables need adjusting for the front o2s being further down the exhaust?

Thanks very much.

There's a whole lot of stuff in the background that needs to be changed for all of that including the tb and intake manifold. In fact about 20 some tables ;) Otherwise, get it as good as you can.

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Originally Posted by GHuggins

There's a whole lot of stuff in the background that needs to be changed for all of that including the tb and intake manifold. In fact about 20 some tables ;) Otherwise, get it as good as you can.

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I Have updated the tables for the manifold and throttle body, along with the cam specs from btr. Mainly looking for info on the O2 sensor tables that need changing and how to turn off the cat warm up tables.
Thanks again.

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Originally Posted by Thomasen15/5.3

I Have updated the tables for the manifold and throttle body, along with the cam specs from btr. Mainly looking for info on the O2 sensor tables that need changing and how to turn off the cat warm up tables.
Thanks again.

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Trust me. You haven't. In fact you need to put the one etc scaler table you have access to back to stock if you can't change the background tables ;) Like I said there's roughly 20 something tables that have to be changed in the background for all of that to be right. EPA won't ever let hpt put the O2 settings back in, not that they ever had them all in the first place and if the background tables don't agree with the ones you can change it can cause some serious problems. Been there and done that so to speak.

OK, so you are saying i need to set the throttle max area table back to stock? or the MAX % area table? I get it about the EPA stuff, just wasnt sure what everyone was doing for vehicles for off road use with no cats.
Thanks for your time

Throttle max back to stock.

For it to be right everything needs to be changed. Even the torque models and vve for the moving cam throttle control. You're just kinda limited on what you can do so you have to work within those limits. If nothing else and you can't get those necessary tables changed i highly recommend putting the rear o2s back in.

Put cats back on it. The gains from going catless are minimal. The problems created by going catless are many.

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In regards to the cats, not my truck, not my choice, Ill recommend it to the owner, but this is the path he chose...
So even if it stays catless, fit rear O2s?
And just so im totaly clear on the Throttle, even with the bigger 6.2l throttle body, keep the factory 5.3 throttle body settings.
Thank you all.

Yes and yes. Now if you can for the TB, find and correct these in the background tables or contact Will or Dave to get them defined if you have User Defined Access. Will's website is minigeist if you google it. Rear o2's need to go back. In the pic that's effective area and max etc just like the one in the main calibration.

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Originally Posted by GHuggins

Yes and yes. Now if you can for the TB, find and correct these in the background tables or contact Will or Dave to get them defined if you have User Defined Access. Will's website is minigeist if you google it. Rear o2's need to go back. In the pic that's effective area and max etc just like the one in the main calibration.

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So for a ported L86 intake and LT5 throttle body on my L83, I'm better off setting these tables back to stock? I do not have access to those tables you mentioned.

Manifold volume if you have it you can change. Throttle max you need to leave stock.

Got it. So without having those extra tables, changing the throttle area limits to match the TB size creates more problems over just leaving the stock settings in the tune. After reading into the this swap a little more, I'm tempted just to put the L83 intake and TB back on. Truck definitely feels like it responds better with it but I did a Flex Fuel sensor at the same time so I'm really not sure if the gains are worth keeping it on. Excuse my ignorance. I'm just getting my feet wet with this stuff and eager to learn.

I'm definitely interested to hear your results once you put the throttle settings back to stock. I copied the driver demand tables from a 2018(I think, memories not what it used to be) into my personal truck, 2015 5.3 sierra and really like the difference in throttle response.
In regards to the throttle area table on the 2016 I'm working on, still waiting for the rest of the exhaust the customer ordered to show up to finish this thing up. I appreciate Greg's advice and I am certain that he is correct. I too am learning this and for me it's kind of frustrating that hp tuners provides access to half the tables required to perform a specific task ( like a lager throttle body). Either put it all in or remove it... seems to kust be creating more issues. I know now that you can upgrade the user defined parameters, but that seems a little excessive for what on the surface seems like a simple enough thing. But I'm probably wrong...
Maybe the complete tables will be included in the next software release?
Cheers guys.

HPT does this with a lot of the tables. I don't understand why, but they'll only put in half of what you need, so you think you have everything only to find yourself going in circles spinning down the rabbit hole chasing phantom problems or self creating your own. The L86 components are worth it. They just need to be set up accordingly.

Minigeist, if you google him, can update your background tables for you for the tb change so you don't have to purchase user defined parameters or if you have user defined parameters he can send you the xdf's so you can change them yourself although keep in mind you'll need the tables out of an l86 in the first place to update the l83's. Will can even go ahead and put those tables in yours while providing you with the xdf's. One is effective area to correspond to the intake manifold and tb and the other is the throttle body size. Dave is who linked me to the other max throttle body size table. Now why GM has multiple of the same tables is a question on it's own...

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Originally Posted by GHuggins

HPT does this with a lot of the tables. I don't understand why, but they'll only put in half of what you need, so you think you have everything only to find yourself going in circles spinning down the rabbit hole chasing phantom problems or self creating your own. The L86 components are worth it. They just need to be set up accordingly.

Minigeist, if you google him, can update your background tables for you for the tb change so you don't have to purchase user defined parameters or if you have user defined parameters he can send you the xdf's so you can change them yourself although keep in mind you'll need the tables out of an l86 in the first place to update the l83's. Will can even go ahead and put those tables in yours while providing you with the xdf's. One is effective area to correspond to the intake manifold and tb and the other is the throttle body size. Dave is who linked me to the other max throttle body size table. Now why GM has multiple of the same tables is a question on it's own...

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Hey Greg. What's the best way to get in touch with Will or Dave for those background tables? I tried direct messaging Will last week but haven't heard back. I didn't see any contact info on his website either. Thank you

Well, I said that and then found out Will has shut things down for a few months until he can get caught up with several other things. I think he even took down the site to be able to do so. I know Dave is also very busy right now coming out with his new port injection system. You can try PMing him and seeing if he can help you. If you did the 6.2 tb and intake manifold you will need the etc area and etc max settings changed. Those are what I normally do for that mod. I unfortunately don't have the ability to define these tables myself or have them for every OS out there. I have several defined, but VERY far from all of them. Dave may also not want to bother with this stuff as he has several other things going on. I really should have asked him before I ever mentioned his name, so if he's reading through this and wants me to take his name out, I can ;)

Well bummer. I totally understand though. Truck seems to run fine with the LT5 throttle area limits. I put the L86 throttle area limit in and my timing at idle went up about 10-12 degrees so I changed it back to the LT5 settings. Sitting between 0-5 degrees now however, I had lowered the torque tables at idle attempting to get fix some negative timing which is probably why it went way positive with the smaller throttle body area. Other than that, I know I need to dial in my MAF and VE tables. Planning on getting a wideband very soon so I can really dig into this thing. I appreciate your help and the information you share on the forum.

If you can't change that background table set, you might want to put that etc max setting back to stock. I've seen in rare instances where having the 2 so different would actually cause some idle self rev issues. You've just seen where it caused the idle torque and throttle position to change, which all of that will change when the background settings are right too. Since you have the lt5 tb, the main background table you need to change is the max throttle area. The effective area table from an lt5 probably won't work. It should, but I haven't done one of those yet to know 100%. I really need to set aside a couple of days with Nick and go to his place with some different tb's and get good effective area tables made up on his flow bench. Guess I would need an intake setup for correct data for that too?

Have I seen your cal? I can check to see if I have them for yours, but odds are I won't, just a fair fyi :)

As Greg said, you need to adjust things that control the throttle on cold starts back to stock and start over. Catwarmup has been removed by HPTuners as the EPA came after them over that and a few other things. If you have an old enough ECU and an older version of HPT 4.x, you can turn off cat warmup.

But since you likely cannot, you can do a few things to make it not pull so much timing. The reason its pulling so much timing is that your throttle and torque values are incorrect and its going crazy. An easy way to keep it from doing that is to raise the minimum spark split injection table. This will keep it from dropping to very low timing values on start, but the startup idle rpm may race a bit. Then you need to adjust the base and split airflow tables to get this back in line some. Then there will be virtual torque and VVE changes to get it in order. Essentially, you have the tables to solve your issue the HARD way. HPTuners no longer allows for Cat Warmup to be turned off and also doesn't expose a dozen other tables that could be helpful. I know tuners who have sent HPTuners definitions for things but HPTuners still doesn't add them. They have no real competitor so they aren't going to ever answer the questions or comments. User Defined parameters was there way of appeasing the needs...but 99% of tuners don't have the ability to decompile code and find hidden tables.

Anyhow, yeah you have quite a few things to work on to get it to play nice on startup. Removing the rear O2's is another issue on E92 ECU's unless you have access to background tables to turn off the fuel checks. Otherwise the car will forever run a fuel test every so often (typically 2-3 run conditions immediately after filling up with fuel) to verify the rear O2's are responding properly. With the O2's missing, the ECU see's no response and ends up pulling a lot of timing and dumping in a lot of fuel to get a response. I've seen the timing go into the negatives and Lambda go into power enrichment levels at idle due to this. Fortunately I think there is a timeout limit where the ECU will stop trying to run this test and get no response and since you have the O2 codes removed, it wont set a CEL. But then when you refill the fuel tank it seems to reset this timeout and try all over again for a set number of test attempts. This behavior was observed by myself and then with some background tables it was solved and these tests no longer run. But again, HPTuners doesn't expose the tables needed to solve this in all E92 vehicles. I have seen some vehicles that have the table defined by HPT though and its only in the latest Beta.

As for your O2's being further away from the engine, pretty easy adjustment and well documented on the forums here if you search for it so I won't expand on it since there is plenty of reading material already.

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Originally Posted by GHuggins

Have I seen your cal? I can check to see if I have them for yours, but odds are I won't, just a fair fyi :)

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I'm not sure what you mean by cal. Sorry just a newb to this.