CanadaLY6

I've been a lurker on here for about a year, ever since I bought my 2008 Suburban LTZ 1500.
The 5.3 started smoking on start up and burning oil, last month it got really bad so I decided to do an LY6 swap to get an affordable used motor with no AFM.

I picked a local shop that's very reputable with monster Corvette builds to carry out the swap as there aren't too many LS specialists around me.
I dropped off a low mileage junkyard LY6 and the truck, they chose a Comp Cams 212/218 cam (VVT deleted) to put in it along with chromoly pushrods and double valve springs. After they were done they dyno tuned the ECU and the transmission as well.
Other than that the truck was stock (no intake, air filers, headers, etc)

After seeing some of the dyno sheets on here I was hoping for a 370ish RWHP (sorry I'm a noob so I have no idea what's realistic).

The truck only made 304RWHP and feels even slower than that.
My original intention of the swap wasn't actually about a ton of power, more to get rid of the AFM and have a motor that dosn't smoke.
Since the motor was out putting in a small cam that would feel like stick seemed like a good idea.

I've got some problems now:

1. I am having an intermittent vibration when the truck is idling, it would best be described as a misfire. It's not constant, sometimes (rarely) the truck will go 10-15 minutes and be glass smooth (like it was when i dropped it off with the stock 5.3). Other times it will miss so badly that the engine will shut if for .25 of a second and all the interior lights will shut off and the vibrations are so bad that its embarrassing to have anyone in the truck.
When I am coming to a stop its hard to do so smoothly because at slow speeds it has a slight jerkiness when I'm on the brakes.

I took the truck back and they said it was spark plug wires, they put brand new ones on and it does the exact same thing. They played with the tune a but and its exactly the same. Now they say its the cam and that's pretty much all its going to be.

Does anyone else have this cam? Is this how it behaves? If so I am going to put the stock cam back in, this is my family hauler we take the kids on trips with.

2. The cruise control no longer works properly since the swap. They say its not related to the swap, although im certain it worked fine as I had just done a 16 hour trip with it two days before I dropped the truck off.
Depending on what interior accesories I have running the Cruise control wont work. ie: I can't have my interior fan above half way, opening the sunroof will shut off the cruise control, same if I turn on the seat heater.

Has anyone had this happen in a swap and know what it might be? Can I be related to the bad idle?

I've put in a K&N cold air, had the Injectors flushed. They told me they used my old injectors and coils which were all running perfectly in my old motor so i dont think its the coil, the spark plugs are brand new. I did a compression test and its a perfect 150 on all 8 cylinders. Still no luck and the vibration is very frustrating.
I want to get longtubes and do a bit more to it, but don't want to do anything until its right.

Thanks in advance for any ideas!

Suburbazine

It kinda sounds like they put in a tune that had DOD enabled. But there's obviously a multitude of issues with the swap, electrical related. Cruise control shouldn't be lost.

CanadaLY6

They say the swap has nothing to do with the cruise control. Any other shop I go to has no idea where to even start with it so I was wondering if anyone had experience with this, maybe something that's easy to hook up wrong I can check?

The dash always says V8 mode so I'm not sure about the DOD.

gagliano7

Had the same problem and it ended up being a bad coil.

2xLS1

iTrader: (25)

What is the LSA on the cam? Is the SES light on or does it ever flash while driving? I occasionally see ground issues when engine swaps are done. Sometimes just a ground bolt not tightened all the way. Misfires real or false can disable the cruise control. The peak dyno numbers seem about right with that small of a cam especially if you still have the stock exhaust with cats. There should be noticeable gains from 5K to 6K rpm though.

Vortec350ss

iTrader: (20)

for starters 370 is more than you can expect without other mods like headers etc in a truck drivetrain. That is a very small cam. It should be silky smooth like you are describing.

CC can be sometimes related to brake lights or something stupid. It also wont work if the truck is detecting a misfire. Are there any codes? Sounds like there may be a misfire with the way you describe a rough idle.

CanadaLY6

The SES light is never on, the LSA is a 115.
There is a good bit more power above 5k, especially compared to the stock 5.3, but its kind of a waste since the truck is never revved up that high. I use it to occasionally tow, go on trips with my family and as a daily driver. I was hoping for extra low/midrange power that I could use, lol.

The cruise control issue is solved, it took it back and they said it was a bad ground. The cruise is working perfectly now.

After I took a look at the rail and showed them that its never been off they said they replaced the intake. I reminded them that the old intake was catherdral and the new one was rectangle they said they must have been confused and that the injectors weren't replaced.. I'm assuming the coils weren't either.
They said that cylinder 5 misfires occasionally and they are saying that its due to lifters, but its not bad enough to replace and is within spec. (?)

The truck has a light vibration most of the time, that sometimes become very noticeable, especially sitting in traffic.
That hasn't changed and that's what I really hate about my truck ever since the swap.

CanadaLY6

Ill try moving the coils around and see if the miss moves with it.

I could live with the power if the idle was as smooth as it was before, but for the poor idle and driveability I would want a hell of a lot more. Lol

I'm being told that the poor idle is just part of this cam and something I have to deal with. Are you telling me that is BS?

2xLS1

iTrader: (25)

A 212/218 115 LSA in a 6.0L should idle smooth. I recently tuned a 6.0L truck with a Comp XER 220/220 114 LSA and it idled smooth at 685 rpm in gear with a stock converter. It's probably going to take a good trouble shooter with a data logger to see what is really going on.

CanadaLY6

Could it be a tune issue?
The problem I'm having is that no shop around me wants to touch it because of the cam and motor swap; the shop that did the swap is telling me its normal for the rough, intermittently rough idle.

I'm starting to think ill have to try and figure it out so just wondering if any of you knew where I should start.
Thanks in advance!