I've been fighting misfire for a while, and found TSB talking about Ground G103. Wanting to clean up the connection, which means i need to FIND the connection.
'06 5.3L 'Z' flex-fuel engine

Where is this ground? I didn't see a good reference point in the TSB picture for the older engines, not nearly as easy for me to get my bearings as the '07 that shows the oil tube.

Also, the ECM ground, this is different from the main battery ground, right? Because that appears to be under the engine on the left (driver's side) bottom of the block, and doesn't appear as expected per the TSB.

Any insights would be appreciated, I'm back on my fishing expedition after taking a few weeks off...
Still getting P0300 misfire almost every time I start the car, replaced knock sensors, plugs, wires, coil pack, cam sensor, intake manifold, fuel treatment, swapped injectors, compression and leak-down test came back good, so I've done most of the 'usual suspects' for a misfire - still no other codes like running lean, etc, just P0300 random cylinder misfire.
I know it's mostly Cyl 1 with occasional Cyl 8 based on misfire counters looking in a Tech2 - ie both banks, sequential in firing order.

 

I believe the ecm has an "internal" ground. That is one or more of the pins on the ecm is to ground. The battery is frame ground, therefore the ground to the ecm is common with the frame. If you suspect it is a ground issue, and since you've replaced the knock sensor after you unhook the battery, pull the connector from the ecm. Using a quick dry electrical contact spray cleaner, spray the connector both sides. Reinstall. There is nothing wrong with adding a bonding strap (ground wire) from the engine to frame, try that.

 

its part of the main negative cable for the battery harness located at the left front of the engine block

 

Ha! I just posted that same info for someone.... give this a read.....https://chevroletforum.com/forum/tah...ing-5-a-54227/

 

Tech2,
Thanks for confirmation it's part of the main battery ground, I have successfully traced that wire to the engine, and indeed it was on the left (looks like easiest access is to remove skid-plate and go from under the car)

in2pro,
I had already seen your post on Misfiring in #5, which is what promped my question, actually, (I didn't want to hijack the thread). I saw the picture, but couldn't get my bearings on what the other parts were in the picture for reference. Also, the notes said right side of the engine, and I couldn't figure out where that was, wasn't seeing a obvious ground on the passenger side of the engine...