Sniper/Hyperspark all of a sudden have a miss

[origcharger]

My Sniper efi/Hyperspark system has been working great for months, the other day I was coasting down a hill and all of a sudden it developed a misfire. The one thing I notice is my air fuel ratio goes way lean on deceleration. I have checked compression and replaced the plugs. The spark that Hyperspark CD box can throw when a plug wire is removed has me reluctant to do a crude cylinder balance test. My oxygen sensor reading, it seems like it would go rich if we have unburned fuel in exhaust. Just wondering if the O2 sensor is pointing me towards the problem or if it is the problem? And of course the O2 sensor is only getting its reading from one bank on this 440

 

[vance.dykes]

go buy a spark tester and install in the spark plug boot and see if spark is there . check the basic's fist cracked cap/ burnt plug wire or spark jumping to ground from spark plug boot.

 

[origcharger]

Update; Have wicked spark at each plug wire, have gone so as to check cooling system for combustion gases. Tracking down a leak down tester now. Now wondering if anything appears amiss with these sensor readouts;

 

[andyf]

A miss could be most anything but you might be able to track it down using the data logger. The built in data logger is a super cool feature on the Sniper. Take a data log showing the miss and post it on here as well as a copy of your current config file and I'll take a look.

 

[origcharger]

I thought I could hook up this Holley dash and get the data log and config file but get these messages...

 

[origcharger]

A follow up; After leakdown test, fuel pressure test, verifying camshaft health and a swap back to a non Sniper EFI controlled ignition system. I still had the low speed underload miss, O2 sensor readings going lean on acceleration and a new development of 1,000 to 1,100 rpm idle despite the target idle setting of 730. So on went a new Sniper EFI and shazam it runs like a top again. Lessons learned.

 

[beanhead]

Just FYI a misfire will cause a lean reading, not rich, as it reads the unused oxygen. I hope it was under warranty!