So we swapped out a pretty much stock 4.8 to a cammed 6.0, now im having some issues. Its a lq9 with a tsunami cam from what the guy told us.

First off the rockers were tight on one side but the other. So just to be safe I opened up timing cover and all that was redone to get timing marks back on.

Now the motor is in the truck and fires up. But this is where the problems start. At first it would idle then have a hick up then idle fine for a few seconds and the hick. Now It'll idle fine then back fire through the exhaust a pretty loud back fire at that. So obviously the valve timing is good. So could it just be all in the tune because of jumping from a 4.8 to the camd 6.0? It would go all the way to 32 degrees of timing when it hickuped. The backfire could only be caused by what? Fuel leaking down into the exhaust or a valve staying open? It did say random misfires a p0300 I think.

Any info much appreciated!

 

are you using the ecu from the 4.8 or the 6.0?

 

4.8 arent they the same?

 

ah so they are my apologies, did you replace your rear bank o2 sensors? i had a nasty misfire in my car and it was the cause of a bad o2 sensor

 

Did not how ever there aren't any cats there anymore either so im pretty sure the oxygen sensors are wacked out. But it wasnt doing this backfire before just after this swap lol

 

Sounds like it still needs a good tune. And I'm pretty sure you're still going to need those rear O2 sensors back there to make the program happy unless you can cut them out entirely, just a guess.

 

I had a back fire in my 02 lq4 and came to be the egr block off doin exactly as you stated every few seconds

 

TheWolfMatt.. so you think the tune is behind this?

95badboy... where exactly does that egr plate go? This lq9 has the 4.8 intake on it. If I remember correctly there was no tubes on fhe side of the throttle body/intake.

If it helps its a 01 4.8 1500 going to an 06 6.0 from an escalade.

 

this should be it, i read on another thread that its the same size as a LS1

EGR Block off plate
GM PART # 12558346
CATEGORY: Engine Fuel Intake Manifold
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $22.03
PRICE: $13.06

 

Ok so ya im pretty sure that plate is there already.

 

Wait... are you running the stock 4.8 computer with the new engine? Not tuned or anything?

 

Ya thats what were doing. I was told that the computer should be able to worl enough to get the engine running

One other thing I just noticed is I hooked up the scan tool and saw that the fuel trim is disabled and that the short terms are at 0% while my long terms are at 0 when the engine is on but as soon as I turn the engine off the long terms go to 23/25% while #6 cylinder has the most misfires theb once rpms go up a little bit #6 stops then #2 climbs

 

you need to completely ignore anyone who said it was OK to fire that engine like that. Just hope you haven't broken anything yet.

 

What would break? Just curious

 

He's right you know, you could have hydro locked that nice 6.0 and then you'd be in a world of hurt. With any engine swap, even if it's the same engine that was in the car/truck, it should get a good tune done before you run it.

 

Well good thing it isnt locked up lol he has a diablosport trinity for the truck but I think he bought it from a guy that didnt load up a stock tune to the car before it was sold because its not letting him do anything besides view parameters.

TheWolfMatt and 96capricemgr thanks for the advice ill be sure to do a tune next time. If it thats bad for an engine why would people tell me to just go ahead and start it thats what bugs me. Their logic was same computer for both engines so it should be able to learn enough to be started.

 

If you upgraded your fuel injectors you could be in trouble. If you used the same ones from the 4.8 you should be ok.

 

Stock 4.8 fuel injectors.

Another question when we had the engine going it seemed that the valve train was a noticeable more noisy. Is that common with cam upgrades?