Octane Booster with MMT to pass NOX. Yea or Nay

First the "main event" parts of NOx.

Dunno how they do it in Masschusetts, but in some states the timing is part of the check -- if you successfully retarded static timing beyond the ECM's ability to twiddle it on the fly (and the car still ran), they'd either fail you for its being out of spec or insist on adjusting it.

Cleaning up the EGR system was probably the biggest thing -- IF it's working right. That's the main way NOx emissions are cut down. Timing and mixture also affect NOx but you risk running up your hydrocarbons, and you don't have a huge margin between the measurement and the limit on those either (unless you want to replace the cat maybe?). See for instance

As for MMT, I'm having trouble finding much authoritative information on a one-shot use of an additive that features MMT. This report from Canada, where (in contrast to the US) MMT is a common component of gasoline, suggests that MMT (at least at the levels commonly used in gasoline itself) will probably reduce NOx levels in older smog-controlled cars but might be a mixed blessing or a detriment in Low Emissions vehicles and beyond: also this paper, which suggests that, at least in some cars andover a longish term, MMT can increase emissions and leave deposits inthe engines and contribute to cat plugging (not what you want to do ifyou're marginal on HC, never mind its performance implications): A layman's summary of these issues may be found at MMT does come in for some discussion as a fuel-borne catalyst in

*diesel* engines, which AFAIK do not customarily have an exhaust catalyst.

Now for a couple of practical matters: how many shots do you get at smog recheck before you get declared to be a gross polluter or something and enter some fresh hell; and how much does it cost you each time?

Cheers,

--Joe

The present state of afairs on EGR is this: when the engine is reved, the diagraphm on the EGR goes up and stays up. When pressed all the way up with finger at idle , the engine is very rough, but does not stall. There appears to be only one runner to all cylinders, not individual to each cylinder. My conclusion is that it is working.

I have 2 month to fix this. I have one free test. I believe if I fail again, I can pay for a test again ($30). My plan was to try the easy way first, and if fail -- replace the Cat. Canv with a $110 direct fit aftermarket. I have a $200 budget to get this car to pass emissions.