Another Front Crossover - Right on Schedule !

[Nechaken]

I was taught by my childhood friends that to clean the valves take it on a freeway and/or frontage road run. Driving up a long grade on the freeway in 3rd, get the RPM's up around 5k RPM's and let it work. But I have zero evidence any of that matters. It sounds more like an excuse to drive at the top of the power band.

In the case of physical cleaning the risk is getting carbon debris that isn't really a problem down into the jug area and could get on top of the rings and potentially score the walls but I haven't seen that. If its running rough then potentially it could be valves not seating and for that the heads would need to come off.

That should have a greater effect on a port-injected engine. But on motors like the AJ, the injectors shoot the gasoline directly into the cylinder, so the valves aren't being washed by whatever detergents / solvents are in or added to the gas.