Popping from intake and exhaust after cam.

[jimmyp3353]

Replaced cam and did a dod delete and got a tune. Also replaced plugs with ngk's on my 09 GT. now after the car has been sitting over night and I start it it popps out of the intake and exhaust for a few seconds. Car runs fine and has plenty of power and zero DTC's, just trying to figure this out. Could it possibly be an injector leaking while the car sits causing fuel to build up in a cylinder?

[Crazy Paul]

Could it possibly be an injector leaking while the car sits causing fuel to build up in a cylinder?

Possibly, and well worth investigating considering the possible consequences if it gets worse.
Other less likely culprits....
a) bad camshaft position sensor connection at the front left of the engine, beside waterpump.
b) incorrect cam timing gear installed onto new camshaft.

[jimmyp3353]

Possibly, and well worth investigating considering the possible consequences if it gets worse.
Other less likely culprits....
a) bad camshaft position sensor connection at the front left of the engine, beside waterpump.
b) incorrect cam timing gear installed onto new camshaft.

It was a single bolt cam that retained the stock gear. I also replaced the chain for good measure.

[-Ray-]

Push rods can be too long holding the valves open. How much pre-load do you have?

[TooManyHobbies]

Did it just do this once, or more than that?

[jimmyp3353]

Only happens when the car has been sitting for a while. Rocker arms are torqued to 22 ft/lbs on base circle. Pushrods came with the cam kit from newera and are 7.450 on a .575 lift cam with mls head gaskets. The popping only happens like a few times out of the exhaust and sometimes out of the intake only when the car has been sitting a while. There is a small tapping noise I can hear at valve train speed when I really listen which I'm investigating now.

[jimmyp3353]

Its almost like it takes the car a few seconds to figure out how its supposed to run when you start it if that makes any sense. Like it is trying to find Idle (surges) pops a bit and then starts idling and running perfectly.

[Joeygr8gt]

Have the same problem after I changed plugs. On start up it's a loud pop and then nothing

[jimmyp3353]

Have the same problem after I changed plugs. On start up it's a loud pop and then nothing

could have cracked the porcelain on one of the plugs.

[jimmyp3353]

I figure I would update this since I've gotten a few PM's from people with similar problems. Still haven't fixed this problem, haven't had time. Most likely culprits are fouled spark plugs (for some reason) or the cam sensor (cam sensor prevents backfiring and rough start). I'm thinking its most likely the cam sensor since its a problem for literally only 5 seconds after cold startup then it seems like the ecu compensates then it runs great. I originally thought it could be bad (deflating) lifters, but since it is coming from the intake and exhaust it would have to be more than 1 (LS7) lifter which is unlikely. I am going to replace the balancer pulley due to wobbling in the near future and when I do I will replace the cam sensor and see what happens.