86 Maxima, failing NOx. Here’s what was done. What next?

Pull vac on the EGR, if you get a strong responce at idle, it's working well enough to not be the problem.

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Speak a little slower :) What do you mean? Pull the vac hose off the egr do what? I think I know what you mean, but want to be sure :)

Thanks Neil. I get it now. Based on Haynes manual, the diagram shows one large passage from EGR to

the intake. I have not figured out how to remove the EGR valave assmbly yet though to doulbe check -- the manual simply says "remove", so I must be missing something. I may swing by the dealership (I need to pick up some minor parts) and look at the print out diagram and then do the disassembly. Thanks for the tip!

Put manifold vac on the EGR valve at idle. If it makes a marked change (probably will stall), the valve and it's passages are OK.

I am curious, why are you against the Octane Booster. What are the other problems? Especially the one with MMT -- it is claimed to reduce NOx emission See the article

I was thinking of using Prestone 0-60 with MMT booster. Like this one: If anything, can it hurt?

Max N

I'd be worried it might somehow show up as HC? Might work fine I've just never found the need for it.