OK, doesn't appear to be anything going on there. It could be a dead cylinder. Try killing one cylinder at a time and see if you've got one not firing. Broken spark plug while installing headers possibly? I found a grounded wire to a coil once that was killing a cylinder on a brand new boat. Customer kept complaining about lack of power/rpm. It still turned over 4200 RPM on 7 cylinders.

Thanks ,I will try that while its here at work I don't need to be in the water for that.

Make sure all the plug wires are fully seated on the plugs. I hate to admit it but I had a my engine running below par for just that reason.

:cool-smiley-011: I think I found the problem. Number 1 cylinder plug was wet with gas it turnes out that it had enough contact for system check, because I unplugged another coil and openned the key and alarm beep one short beep follwed shortly by two short ones indicating fault.
I tried unpluggin one coil at time but the motors idle did not change. So I tried one of those spark tester that goes between plug wire and plug. It was easier than try to reach each coil under the electronics.
I isolated plug, wire, coil, and after pluggin everything back # 1 fired like a charm. Found the grimlin.
Water retest coming soon

Thanks guys , coulndn't have done it without everybodys help.

Has anyone successfully put O2 sensors in lightning headers without getting the sensors wet?

Myself, Boatingbent and TX_Instigator all run Lightnings with 02 sensors. The Nordics use a custom low port exit header so the collector is pointing at a steep downward angle where the 02 sensor goes. They won't work on the standard lightnings. I learned that the hard way.

http://www.stealth316.com/2-oxygensensor.htmThose sensors on the 496 HO in headers are temp sensors, they atach to water jacket in the header and not exhaust. I noticed that when I put on the headers. I have replaced a few 02 sensors in my line of work and they don't resemble anything like this.
the sonsors were solid brass just like temp sensors, or am I wrong?

Your right, those are the temp sensors. What I want to do is monitor the A/F ratio while on the water, and that requires an O2 sensor(which CAN'T get wet!) at the header collector.
Thanks Bob, I was hopping that vertical collector was enough to keep the water off the sensor. I have a pyro gauge that reads the # 2 cylinder but really would like to know the A/F also. I will get the bungs welded in during the off season. For now I will just keep an eye on the plugs.

We added the 02 sensor bungs to the headers to monitor the A/F ratios.

found my issue bad seapump I guess a little sand smokes the brass pump, They dont make enough pressure at idle , the steam would go away as long as I was moving Im also running imco lowers