colorado2500hd

Hi All,

I have a 2003 2500hd 6.0 with cam, heads, headers, and tune. Per my tuner, I need to use 89 octane or higher, when he tuned it there was regular in the tank (around here regular is 85 or 87 and premium is 91). Ever since I've gotten it tuned, I use premium (91 octane).

Replaced knock sensors when I did the heads with 2 new AC Delco knock sensors, and new harness.

Everything was fine for a while, I put probably 200-300 miles on it. My girlfriend has been using it and filled the tank from almost empty with regular (she can't remember if it was 85 or 87). I drove it and noticed it seemed to be lacking in power, and then check engine light came on - pulled the code and it shows P0327. Went to O'Reilly's and grabbed a couple bottles of octane booster, cleared the code, then everything seemed to be fine. I burned about a quarter tank, then I filled it back up with premium - so at this point it's probably 70% regular, 30% premium, and 2 12oz bottles of O'Reilly's store brand octane booster. At that point, everything still fine, power levels back to normal, then it came on again. Seems like no change in power levels, engine performs as expected.

Idle is a little rough, and it seems to sort of shake at some odd intervals, but I chalked that up to the more aggressive camshaft.

It seems like too much of a coincidence that it's bad knock sensors at the same time that I'm running regular gas, but I know parts can go bad at odd times.

Anyone have any experience with this? Any ideas?

B52Bombardier1

I'd drive it to maybe a quarter of a tank and refill with premium. Drive it gently, no hard throttle stabs, no high RPM operation, no towing. Reset the codes and see what happens.

But it sure seems like a knock sensor could be bad.

Rick