Help!!!
 

ok i just got my car and it has a dead miss. cylinder 1. i checked the lash and its all good. im only getting 40psi. i unplugged the coil and spun the motor over and the valves appear to be okay(dont look bent up top)(i know that doesnt rule that out). under hard accelleration im hearing a clicking or rattling sound(possibly callapsed lifter?) any suggestions would be awesome

is there coolant in the oil, are you seeing excess blow by (smokey air coming out of oil fill hole), can we get a recording of the motor and the exhaust?

theres no water in the oil, it sounds like the optispark is gonna go south to begin with, but i talked to my friend who works at chevy and he said that it sounds like fuel ping due to a bad opti. ive noticed that it has used alot of gas. i live 2 miles from my job and driving it 2 work and back twice has has used almost a 1/4 tank so i can see where hes coming from. maybe its burned a valve seat?

i would hope thats what it is. i have seen a cracked block/head do the same thing. probly better get that head off and check it out. so long as its not a crack it would be a good time to have the heads ported a bit with better springs, push rods and some 1.6 rr's.

well i got it good enough to get me home, dude had...u guessed it bosch plugs. it seemed like it actually wanted to run.my personal oppinion is i may have a bum lifter? but i gotta take the intake off to do the head anyways. 40ish psi...im guessing a slightly bent valve? im new to all this, now a 3800 ill service those all day long. driver side head seems easy. if it comes down the yanking the head then there both coming off, and im gonna get some porting done with some goodies. but anyways my dude said to hook a air line to the spark plug hole and listen to hear were its hissing. im just hoping its something stupid. but can a optispark make it had bad gas milage?

Man, I sure hope you don't have a bad optispark, especially since an LS1 doesn't have one! ;)
Or is your car not really a 98 either? How much does "clone" refer to?

:icon_couchhide::icon_couchhide:HAHA very funny! i got a 93 Z28...

Funny what? I was saying that based on your user name.

i no longer own that car...:icon_nic:

bad opti can have a effect on mpg but going on you having a cylinder with only 40# compression test i would say that is the reason for having poor mpg. you are putting fuel into a piston thats not working and overworking the other 7 to try and pull along that dead hole.