maximer

okay so for starters the car we are dealing with here is an 03 6spd 5.5gen. 156k miles. a couple nights ago i got a misfire on cyl. #6 from what i read on my code scanner. erased the code to see if it would come back....didnt. great ....so i thought. about two nights ago i started feeling some heavy misfire under light loads, didnt really feel it at full throttle past say, 4k rpm. kept feeling worse and worse the more i drove it, sure enough the SES light came on so i pop in the scanner. read a p0335 which i believe read crank position sensor bank A malfucntion something along those lines. this morning i pick up a new CPS, pop it in, reset the ecu, and now drove it around and still felt a slight misfire, just not as worse as before. i also noticed that after i replaced the old CPS with the new one, my tach doesnt work, and im still getting the same P0335 trouble code. help please

maximer

bump ^

maximer

well since nobody wanted to help i figured it out on my own. after much frustration, i did a compression test. every cylinder checked out just fine reading from 150psi-158psi, awesome.......except for one (dramatic music, u know, that dum dum dum sound lol) cylinder #4 was completly pegging a 0 on the gauge. i tested it 4 times to make sure i wasnt doing anything wrong, checked every other cylinder twice and same result. looks like i have a bad intake valve(s) in cylinder #4. i seafoamed the gas tank and a vaccum line leading to the IM and it helped out alot more than i expected. motor after 2k rpm was working back up to par, there was vavle ticking still but much better than before. under 2k rpm it can hardly even idle. i erased the ecu codes to try and get updated ones, and not one code other than the p0300 random misfire code. i forgot to also mention that my crank sensor code problem was my own fault. i installed it a little loosy... took it out.....tightend it the right way and now my tach works and that p0335 crank sensor code went away. looks like its off with the head, and on to the machine shop