Sets a p0300 code at idle

Good morning.

Have you tested the compression?

what is the fuel pressure?

Roy

Compression 150 to 140 on all cylinders. fuel pressure at idle is 57 psi.

Okay thanks.

sounds like it is running lean.

can you read the long term trims with a scan tool?

Roy

That is what i thought. Scan tool shows 5% on bank one and 2% on bank 2. Tested for vacuum leaks cannot find any. Had original manifold gaskets replaced them still same thing. O2 sensors are old but seam to be working properly.

they are reading good.

what are the mass air flow readings?

Roy

Air flow at idle it jumps around between 4.5 and 5.7 gpm as for the voltage i do not remember. Working on other things at the moment can get that if you need it, but will take a while.

Okay, got time. make sure there is no leak on the hose from there to the throttle body and the connector is clean and tight.

Roy

I know the hose is good and connections are tight. i will get those numbers now .

Okay.

Right now cold 1.2.

As the idle came down .8.

Okay, that looks good.

all readings are good. I am wondering if it is a valve related issue. the cam and lifters on these engines are common for failure. removing the valve covers and inspect the rockers for any damage. I would also look at the movement in the affected cylinders.

Roy

I have looked at the action of #7 valves both moving same amount as the rest on that bank and there the same height. Have not checked bank 2. There is one lifter ticking a little on one bank. Is it possible for one cylinder to disrupt the air flow of another on the opposite bank? I have seen it on adjacent cylinders.

Yep, very possible. I would check for the source of the noise.

Roy

I will thanks.

Keep us updated.

Roy