I have a 2006 rcsb truck that came with a 4.8 that I am putting a rebuilt lq9 in it but don’t know if I should tune it or get a base tune on it before the break in procedure or go ahead and break it in with the Ecu still reading as 4.8
also have a 210/218 drop in truck cam and 243 heads on it and Long tube headers
also what’s a good break in procedure?

 

Break in procedure includes a having a good/reasonable tune prior to starting.
Bad tune could cause several issues.

 

Something this mild I would send off the ECM/TCM? for a mail order tune and then do a chassis dyno tune if you think its needed.
Besides tuning the engine on the chassis dyno the tuner can also fine tune the shift points on the trans.

 

The LQ9 will have injectors that flow a good bit more fuel than the 4.8. You will have to tune before startup.

 

And do you think I could start it once just to make sure I don’t have any leaks before taking it to my tuner?

 

It may or may not start, but given the big displacement difference, you are taking a big chance on washing your rings with too much gas on a brand new rebuild. Just getting the parameters from a bone stock lq9 file loaded into your pcm would be enough to crank it safely, but I would not even turn it over as is.

 

He's using 243 heads now. That's gonna raise the compression a lot, over the original 317 heads. I would take the stock LQ4 base tune, retard the timing 4 degrees first, and then add 10% fuel before trying to start it. It probably still won't idle very well.

You really need to get it to a tuner as soon as possible. They can probably send you a base tune that might get you there. Your next best option would be towing it to the tuner.

 

Would it flood the pistons that quick even if it was on for a couple seconds

 

It is NEVER for "a couple seconds".......
Don't risk it.....

 

Really not as big of a deal as you guys are all making it out to be. The computer is just going to see more airflow over the math at lower speeds and do its best to keep up, It's not going to be perfect but I really don't think it's going to hurt anything, you see I've actually done this before without any problems when I swapped my 9.5cr 4.8 long block for a 11:1 (at the time now it's 11.8:1) 6.2 long block. I broke the engine in hard when I first started it floating between 2 and 3K for 30 minutes to bed the rings and some more revving and then an oil change and then drove it like crazy. I didn't have HP tuners at the time and so I drove it for at least two or three weeks before my friend was able to help me with the tune.

I could be wrong but I thought all the truck intakes and injectors were the same regardless of the displacement?

Either way I think it's okay If OP kicks it over You can button it all up. Take care of leaks etc. It's fine, Just don't race it until you have it tuned

 

I've done the same many times. I also believe all truck injectors are the same so no worries there. I've switched from smaller to bigger motors and big to smaller motors. All fire up and run just fine, stock to stock the factory tune and fuel trims work perfectly fine. This cam is small enough that firing up and running would be fine in my book, I wouldnt go wot 6k pull but partial throttle driving under 3k isnt out of the question.

 

Make sure the injectors are the same before you start without a tune or put your 4.8 injectors in then you will be fine.

 

Listen to people and don't start it....or don't and deal with the consequences.

 

What is flooding the Pistons?

 

I towed to tuner and didn’t start it either and he called to tell me that it runs rough and doesn’t move on it’s own power
I don’t seem to understand the issue because he said it hasn’t thrown any codes and also almost everything in the motor is new excepts from spark plug and wires and also the injectors those reused from the 4.8?
what could be the issue?

 

Should have started it up yourself, That's all he did and who knows what else. Of course it's running rough The fuel trims are off, What kind of tuna software is he using? He should be able to tell you what's going on with it and If he doesn't have VCM suite so you can look at everything running in real time he's not an ls tuner What does not move under its own power mean exactly? Like something's going on with the transmission or it's actually stalling?

After years of believing others were smarter than me and my car I finally wizened up and bought the software for myself. Best purchase I've ever made in this hobby hands down

 

I didn’t start it because before I didn’t have a 6.0 file on there and he’s running hp tuner I think
I really don’t have a clue by that because he said the transmission oil not being topped off but i was sure of it and the transmission was a rebuilt one from a trusty builder that i had already tried on before swapping my motor so that can’t be it
That’s what I’m starting to think Also starting to believe is just a case of wanting more money because he said he’ll give me a diagnosis for 110 an hour just to see what it is not even fix it

 

Should have just started it in your driveway…and the intakes and injectors on The trucks are all the same unless its a flex fuel then you have 50lb injectors i believe….regular fuel ones are 29lbs i wanna say…i could be wrong though….but the last thing id ever do is tow a vehicle to some con artist tuner and tell them you dont know whats wrong and you are mechanically incompitent…..they just see green and dollar signs at that point…..put new plugs and wires on that engine too, that is the very first thing that should have been done on any and all engine swaps….but yeah you can run it on the 4.8 tune it just wouldnt be wise to go hot rodding it till you get a tune on it, also you dont have to tow it anywhere, a good tuner can always do a remote tune with great results…..i would pull your truck from that shop before he decides to ripp you off for any more money and take you for a very expensive ride!!!!!…..and research , research ,and more research…….alot of guys on here are very knowledgeable but the better half are keyboard warriors and dont know **** and have more money than brains, those are the ones who are gonna tell you it cant be done and you have to spend more money and buy this and that….dont fall for the okie doke!!!

 

On all my LS swaps unless I buy new injectors I send the "old" ones to be cleaned and flow checked.
A somewhat local shop charges about $250 for 8 injectors.

 

Or you can get creative with a 9volt battery and a can of carb cleaner or a couple syrynges…..several low budget videos on you tube showing diffrent effective ways of cleaning injectors