quinnfiske

I think you have the octane thing backwards, higher octane causes cooler combustion temps and therefore less detonation (knock). If Tom's problem is high NOx, he needs to cool the process down.

I wonder if some of the tuners that produce DME chips could write emission-friendly maps for this purpose. Perhaps leaned out a bit with retarded spark or something. Anyone ever seen anything like this?

Tom_DB1

Just got my car back from the Gold Shield facility and it passed smog after alot of testing and $1000.

Now my NoX is down to 560 at 15 mph and 430 at 25 mph. Even the smog guru had problems finding the cause. Removed and tested almost everthing, injectors, fuel pressure reg and damper, timing, O2 sensor, cat. No change. Replaced ALL exhaust and intake gaskets and a little/alot exhaust welding. That was it, when they pulled it all apart they found multiple small (hairline fractures) exhaust leaks that skewed the O2 sensor and cat operations. The previous owner had wrapped the exhaust and crossover which causes premature cracking. Thats ok for a race car but not for a road car

And take this for what its worth to you but according to the state smog guru, using race fuel may cause your Emission readings to change because of the diff additives but will not lower your NoX unless its detonation related and at 8 to 1 compression and no boost he laughed at me and called it a myth. He said there is no additive that will lower NoX without causing other things to go out of spec. If there was it would already be in your fuel.


Tom

ibkevin

Hehe, the smog **** handed me my *** today!!

Worst numbers ever.

I've spent the last two hours on the search function and once I get a few more answers I'll post a thread on it.

NO at 15mph was 1709ppm, crazy stuff.

quinnfiske

My mechanic told me the same thing about exhaust leaks. I did'nt believe him, but after this experience I changed my mind and will keep a closer eye on my headers.