I was getting some surging along with what sounded like a lifter tapping for a while now so yesterday I replaced the fuel filter, pcv valve, ran some sea foam through the pcv valve inlet to clean up the engine, flushed it all out, put new spark plugs back in afterwards. Truck seems to run ok so I did a few WOT runs and it seemed to run a lot better. I then did a WOT run and hit the nitrous for about 2 seconds and the ses light came on and cleared out. Well today I tried it again, hit the nitrous and ses light came back on and stayed on. I scanned it with my crane cams tuner and code was a 0305. Does anyone have any idea what this could be?

 

0305.........cylinder number 5 misfire detected- recheck plug and plugwire. Also, as I have found-out the hard way, just because a part is new out of the box it doesn't mean it can't be defective.

 

Thanks, is there anything else that can cause a missfire in that cylinder?

 

Not unusual using nitrous. It's recommended you close the spark gap a little. On your engine I think they use about .035 gap. If the engine's too lean or detonating from too advance a spark, you can also notice cracked porcelin around the center electrode. A trick I use to check spark, is to inspect (carefully) your running engine in a darkened garage. I have seen spark intermittantly jump to a header or valve cover. It indicates a bad wire or not seated properly. You can also hear a pop when it jumps.

 

you said you put new plugs in, what gap did you put the plugs at? if it's the updated gm plug, it gaps on .040, not .060 -

 

Im using NGK TR55 gapped at .035, I have always used those for a year now while on the nitrous with no probs. Before I did the sea foam, I took my plugs out which had less than 1000 miles on them to avoid ruining them and put some old ones in. After I flushed the engine I put my new ones back in so essentially they are the same ones I had, I even put them back in the same order.

 

TR55's are too hot, you need TR6's (one step colder) or R5671A-7 (2 steps colder). That will probably cure your problem. When the Wood Hauler ran that Lightning a few weeks ago he had new plugs in and ran a strong mix of fuel additive, it stated cutting out, and altough the plugs looked fine when we pulled them they were not. Put new plugs in and problem solved.