2017 Cadillac Escalade 6.2 Cyl 6 misfire

The Truck has a dead miss on cyl 6 running compression is around 2psi at idle and may reach 4psi on snap throttle. using a conventional compression gauge that cylinder builds 150+ psi of compression. i have a couple of screens of pulse and secondary info attached. lm looking for general advice on tests and solutions.

What in-cylinder transducer were you using for your capture? Would you be able to put cursors on the peak compression and lowest vacuum points?

First thought when looking at your in-cylinder waveform is no intake valve opening. Or, a severe lack of intake valve lift/duration. That'll cause low running compression and deep vacuum during the intake stroke.

I don't have a running example on hand, but I recently captured this from a '16 Tahoe with a stuck closed intake valve. Cranking, APT-100, 10mV = 1 PSI.

 

From here, your suspect list is pretty short - Failed intake lifter, flat cam lobe, bent pushrod or a combination of all three. Rocker arm could have failed, but I've never seen it on an L83/L96.

You can pull the valve cover to confirm lack of rocker arm movement during cranking and visually check the pushrod. Beyond that, either the engine is coming apart to replace lifters/camshaft, or the engine is getting replaced.

Thanks for the input Tyler. Im using a Rotkee Ps100 with Mt pro 4.1.

I was think the same i hooked up a pds to the intake and came up with this

Engine running? I'm honestly not great with running intake pulse waveforms, especially on V8's. Maybe others can chime in.

Yes its running @ idle

Tyler wrote:

Engine running? I'm honestly not great with running intake pulse waveforms, especially on V8's. Maybe others can chime in.

 

I'll chime in...

Nobody is great with running intake waveforms.

I'd disable fuel and recapture, while giving the engine a good, long, steady crank.

First thought when looking at your in-cylinder waveform is no intake valve opening. Or, a severe lack of intake valve lift/duration. That'll cause low running compression and deep vacuum during the intake stroke.

That's my first thought, too.

Thanks a lot for the input guys..i did do a crank no start and it looks just like tylers waveform...ill will find it and post it here