HC & CO will usually increase in concentration the richer the motor runs of stoichiometric. Conversely, concentration of NO will begin to decrease. However, don't forget that NO concentration peaks just lean of Stoichmetric and then rapidily decreases as the mixture becomes leaner.

With that in mind ... the motor is probablty running rich at the low RPM setting Send the results of the complete smog test. I am interested to check them out. RGDS, RG > '88 Vanagon failed California smog check at idle test, with HC at almost > three times the limit, but clean at 2500 rpm test. Every other measurement > was well within range. > > The catalytic converter is fine, I believe, and it has new oil and filters, > plugs. > Haven't changed wires yet, timing is ok. > > There is a coolant leak, right head top front area, does not pressurize the > cooling system as a head gasket leak would. Could this be related to the > emissions failure ? > > Any ideas ? > > Ron Antaki >