REACHING FOR STRAWS

[Maximus1]

I have an 04 Tahoe 5.3L Flex fuel. All header tubes read about 400 degrees except for number 6 which is only about 280. I clearly have a misfire. Checked compression and it's at about 150psi. Swapped coils with another cylinder with no results. Swapped injectors with no results. Any idea on what it might be. I just swapped heads to the 799 heads and then the misfire started. Also I did the screwdriver to ear test on the 6 injector and I can hear it pulsing. Getting a Too rich code and too lean code along with airflow out of range

 

[Lord Snax]

Check the spark plug. I have had instances where the spark plug fails but the ignition coil is still good.

It looks like the codes are a result of the swap to the 799 heads. From what I can tell, the computer is trying to compensate for the out of range air flow. So it is running too rich and too lean on different cylinders. Possibly causing the misfire you are talking about, if the spark plug is good. You will need to get the computer tuned by professional to get it to run right.

Hope this was helpful,
Lord Snax

 

[Maximus1]

I figured it out. Before the 799 head swap I had installed longer pushrods (7.425 trick flow vs stock 7.395) to reduce that classic 5.3L lifter tap noise. Well before I installed the 799 heads I had them CNC ported and milled .030". Forgetting about the pushrods I installed the aftermarket ones which put me way too long. Ordered some 7.375 trick flow pushrods and now the engine is very happy