99HRDTP

I'm getting backfiring when at idle or mild throttle application. Does not occur at half throttle and above nor on decel. This has started to occur after replacing a faulty oil and water pump. Also getting a ticking noise from under the hood that increases with engine RPM. Any ideas where to start? Thanks.

Bill Curlee

LS engines are very sensitive to a cylinder miss. When you get the backfire, see if you get a FLASHING (Check Engine Light). Also, during the event (without turning the ignition off), enter the DIC Code checking routine and see if you have a PCM P-0300 C or H code.

That indicates that you have enough misfires to trip the DTC.

With the engine noise, you could have a:

BAD Plug Wire

OR

A damaged valve spring

OR

Bad Coil

OR

Bad Spark Plug

Give all those a look and make sure that you don't have a loose plug wire or bad wire first.

Bill

johnnyzvette

I had this exact problem a few days ago. I wasn't getting any misfire codes or flashing check engine light. It definitely felt like a misfire though. The problem was one of my spark plug wires wasn't seated properly, found one that was loose and heard it click back in place after pushing on it. Problem gone.

99HRDTP

Thanks Bill. We have changed all of the plugs and wires recently. Will check the connections. I feared it might be a spring as the Stage 2 Katech heads and cam package is getting up there in the years.

----
Mike

Bill Curlee

Mike

Bad Spring or bad intake valve QUICK CHECK:

I you have an inferred laser thermometer, use it to measure the temperature of each intake manifold runner right where it connects to the head.
They should all be about the same temp. If you have a bad intake valve spring or valve and the valve is leaking by, that runner will have a much higher temp than the rest.

Bill

99HRDTP

Will do. Thanks again Bill.

----
Mike