[Hostile_1LE]

So, I've been having a weird no start issue, about 1200 miles after my heads/cam job. Car will Crank, and sputter then die. Not sure what is causing it yet, as it happens at random.

I wanted a sanity check and got a compression test done. I got 150-159 psi across all cylinders and less than 10% leak-down. Does this sound acceptable?

I am at 3300' of elevation and it was above 90* F today.

[Kerry]

yes 10% leak down across the board means all good. compression test ahh here their, leak down is what counts.

[FlukeSS]

This might help you some, because according to that thread compression numbers can vary car to car specifically when a cam is involved. But that thread also says tightness of the pressures is a good sign, the tighter it is the better.

https://www.camaro6.com/forums/showthread.php?t=605202

As it pertains to the discussion at hand here to some degree, my car is registering a massive number of misfires way more than 40/cylinder with a stock misfire sensor setting. Cylinder 3 is hundreds even as high as 1800 misfires. Taking my car in the shop on the 29th to have it diagnosed if it is a leak, bad IM gaskets or something. Was hoping to avoid a compression test, but sounds like I may I need it as well.

[Hostile_1LE]

Originally Posted by FlukeSS

This might help you some, because according to that thread compression numbers can vary car to car specifically when a cam is involved. But that thread also says tightness of the pressures is a good sign, the tighter it is the better.

https://www.camaro6.com/forums/showthread.php?t=605202

As it pertains to the discussion at hand here to some degree, my car is registering a massive number of misfires way more than 40/cylinder with a stock misfire sensor setting. Cylinder 3 is hundreds even as high as 1800 misfires. Taking my car in the shop on the 29th to have it diagnosed if it is a leak, bad IM gaskets or something. Was hoping to avoid a compression test, but sounds like I may I need it as well.

Could also be your MSD leaking. I've seen a few threads where people seal it up with RTV. Its design leaves a little to be desired. I've been suspicious of mine since I got it.

[FlukeSS]

Originally Posted by Hostile_1LE

Could also be your MSD leaking. I've seen a few threads where people seal it up with RTV. Its design leaves a little to be desired. I've been suspicious of mine since I got it.

I have an LT2. But, I can say this, the misfires started, then my tuner said try tightening down the LT2 bolts, which I did, driver side was looser than passenger side and bank 1 was registering the most misfires. After I tightened down the bolts the misfires got much worse. Misfires on all cylinders and especially on Cylinder 3 with 7 a close second place.

So we are thinking bad IM gaskets maybe, and a potential vacuum leak. I already replaced the O2 sensors and spark plugs and the issue remains. MAF sensor seems to be good did an unplug test and the car didn't stop running but it was explained to me it would not, I just happen to notice it bogged down as it switched fuel tables off the MAF. Plugged the MAF back in, restarted the car, and it was fine and more smooth, but obviously misfires still there.

So right now IM vacuum leak maybe, ignition coils, or injectors. Hope to not have to do a compression test, but we'll see.

[Hostile_1LE]

Yeah it would suck if it was a bad seat.

[Ventmaster]

+1 on the IM leak being the issue.
The port seal gaskets on the MSD (and OE) IM, according to MSD, should just be torqued to 89in/lbs over 3 passes. Those gaskets "squish" and deform quite easily. You can buy them as a set for a good price in Amazon I think!