2004-2007 Cadillac CTS-V General Discussion Discussion, CTS V P0305 Engine Misfire Code in Cadillac CTS-V Series Forum - 2004 - 2007; I've always had a slight mis at idle but never a code and I suspected maybe a bad valve. That ...
I've always had a slight mis at idle but never a code and I suspected maybe a bad valve. That all changed recently when I installed a cam... Code P0300. Oddly enough when I was changing the valve springs I noticed that the first cylinder on the pass. side didn't pump up with air right away like all the others when I put 100psi to it (I actually used my leak-down tester to charge the cylinder). That cylinder took about 10 seconds or so and I could clearly hear the air coming from the throttle body especially when I opened the plate!
Other than that I haven't ever done any tests like leakdown or compression. My mis is very very slight which most don't even notice, I think with the cam it's just now more pronounced for the PCM setting the code off.
Although it's not a clear cut answer maybe it's a lead for you.
Btw, I've got 73k miles on the clock and I bought the car with 30k bone stock.
After much more diagnosis, I am still having this problem. Leak down tests, used engine block tester, cut open the wiring harness to find any problems, etc.
Brought it to the dealership and they said I needed a new computer. Got a new computer, still the same problem.
It was suggested that I swap o2 sensors on the front bank, but I can't see a good way to get to them. I have been searching on this forum, but can't find it mentioned. Anyone know a good way to get at the front o2 sensors?