Hey all, sorry to resurrect my old thread, but....

Ok, so the leaking has stopped entirely... I just threw in some barrs stop leak. However, piston one is now having timing problems, or something... It won't fire. So I changed the plug, wire and it was the same. The plug and wire were both in working order but, I decided to try it out.

So after doing some reading someone had suggested to another person to 'reset the computer'. So naturally, I disconnected the negative and let it sit for a while. After doing so I started it back up and and it's running on all cylinders.

This will last for about 30-50 minutes, then piston #1 stops firing again. I've been doing a bit of digging and it seems like people replace damn near everything and they can't seam to get rid of this problem. Without any progress...

I guess, I could just disconnect the negative before I want to drive it and then drive it for a bit before piston 1 stops firing again :/


Thanks,
-Frank

 

Have a '99 Escalade with same Vortec 5.7 L VIN R that had a similar problem with misfires.

Are you sure the coolant leak is not internal? Either internal, external or both leak types can occur.

Maybe your misfire/cyl 1 is due to an intake gasket failure resulting in an internal leak that shows up once the engine reaches operating temperature and component expansion has occurred.

What actually happened on my 5.7 li was that coolant was leaking internally at first causing a P0307 and occasionally P0305 error codes(cyl 7 and 5 misfires). These codes started showing with greater regularity. Cleared the error codes with a code reading tool. Eventually (120k miles) the intake gasket failed catastrophically and leaked externally (in Dec '12) requiring immediate intake gasket replacement. I flushed the coolant system removing "DexCool" and replaced it with Prestone "green" antifreeze that I have more faith in. Now the engine runs smoothly and no misfire error codes are generated.

Intake gasket failure appears to be a common issue with GM 5.7 L engines of that time period.

Two other things you might want to look at:
1. Check for condensation inside the oil filler cap, could be a sign of an internal leak.
2. Injector for cyl 1, especially the electrical connector at the spider distribution block.

 

5/8" socket