Misfire from header primary leaking?
Misfire from header primary leaking? Car is a 99 z28 with a 6 speed ~60k miles. Basic bolt ons, stock engine for now. The header primary tube on the #2 cylinder is leaking exhaust gas. Feels like it is coming out from in between the flange and primary tube not from the block and primary. Car has code for random misfires. I replaced plugs and wires problem still existed and that's when I found the leak. Car will be going to a shop to pull header and re weld the flange.
My big worry is that I burnt the valve. Does anyone have a similar experience to this. I have a set of 243 heads and a cam that I was going to install, but I dont want to do the work until I know the motor is healthy. Also fuel pressure was fine and no other apparent vacuum leaks were found. Headers are stainless works and were not welded on the outside of the tube so I'm assuming it cracked on the inside of the flange. Thanks for the help/advice
My big worry is that I burnt the valve. Does anyone have a similar experience to this. I have a set of 243 heads and a cam that I was going to install, but I dont want to do the work until I know the motor is healthy. Also fuel pressure was fine and no other apparent vacuum leaks were found. Headers are stainless works and were not welded on the outside of the tube so I'm assuming it cracked on the inside of the flange. Thanks for the help/advice
you dont think that its dumping fuel to make up for it reading lean on the o2? Also forgot to mention all plugs looked fine and were gapped around 44 thou when pulled, but the #2 and #4 plug definitely looked as if they were running rich
TECH Addict
Joined: Mar 2013
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It can't "dump fuel" on 1 or 2 cylinders. You got bank 1 and bank 2 4 cylinders on each bank 1 o2 for each bank. Your intake is probably leaking because the bolts are loose. They might feel tight but if they ere never gone over the intake is loose when its cold and will set random misfire code. Its some place to start. Scan it and look at the fuel trims and o2 activity but like I said posted its 4 cylinders per o2.
