How smooth should a stock LS1 idle?

[kristov]

Hi guys, I could really use your input on something.

If I put both hands on the intake manifold I can feel irregular skips/misses. The engine runs fine for a while and then a skip/miss. After this it continues to run fine before another skip/miss and so it continues. The skip/miss is just very slight, like when a heart skips/jumps over a beat. I can also barely hear it in the tailpipe.

[Q8y_drifter]

Any CELs?

I have a stock 4.8 in my 2013 GMC Sierra and while it runs perfectly fine it's not exactly the smoothest running engine and does have a bit of a "beat" to it, but then again its a pushrod V8 not an inline 6.

Assuming it runs good and the tune is correct, I'd start with plugs/wires/coils and may be check idle air control valve, it could be acting up. Even a dirty throttle body can cause rough idle issues so make sure its all clean in there.

[iansane]

Sounds like a plugwire.

[M-technik-3]

My truck engine does the same thing. Have swapped plug wires and plugs does not toss any codes either. I just chalk it up to getting up in mileage.

[Mthrizzle]

I am sure that your issue is related to your intake gasket starting to leak..common problem with GM motors

[garretvs]

I put it to an intake gasket or vacuum leak if plugs, wires and coils are good

[kristov]

Intake gaskets are brand new.

[Mthrizzle]

Intake gaskets to the plenum ??..CONFIRM WAHTS CAUSING THE ISSUE FIRST !!! VACCUM LEAK OR MISFIRE ..THEN WE CAN REOUBLE SHOOT..MY ESCALADE DID THE SAME THING AFTER REPLACING THE SAID GASKET A FEW WEEKS AFTER HAVING THEM DONE..TURNS OUT THE INTAKE ITSELF BEING MADE OUT OF PLASTIC WAS STARTING TO" WARP "..BACK TO DOING SAME THING LIKE YOU DESCRIBED...DOES NOT AFFECT PERFORMANCE...JUST ANNOYING