Quote Originally Posted by smdelfin View Post
2 weeks ago, I converted my 1996 carburator Nissan Vanette in Xoom. But up to now, it's still not usable. 2 out of 4 sparkplugs get destroyed. So Xoom suggested I bring the van back to my mechanic. My mechanic tested the van using gas, the sparkplugs don't get destroyed. But when he tested it using lpg, the 2 sparkplugs get destroyed. Why doesn't the sparkplugs get destroyed when using gas? If the sparkplugs get destroyed on both gas and lpg, at least we know that there's something wrong, and the mechanic will open it up. And why only the 2 sparkplugs?

I think your auto-lpg kit is venturi-mixer and the intake is causing the last two cylinders to run a little lean which results in the damaged sparkplugs. A quickfix would be to run slightly richer to compensate for the last two cylinders from running lean.

Also check if the venturi-mixer itself is correctly sized for your engine. If it's too big, it might result in the lpg irregularly mixing with the incoming air.

A more long term fix is to change from the venturi-mixer kit to the SGI kit (running open loop mode) which will have an individual LPG injector fitted per cylinder. This will eliminate the lean running condition of the last two cylinders. This will be expensive and might be hard to do because of the cramp space of the vanette's engine bay.