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Emissions & Modifying your car

32869 Views 43 Replies 21 Participants Last post by  fb6ben
OK this has been coming up an excessive amount of time. First thing's first:

- If you're worried about passing emissions, do not modify your car.

Tuning solutions (FlashPro included) are sold as "OFF ROAD USE ONLY" products, meaning they are not there to help you pass emissions, fudge your emissions, or in any way let you sneak through emissions testing with a modified vehicle. In fact, it's illegal. It's actually illegal for anyone to even try and help you fudge any emissions testing -- there are federal and state regulations regarding emissions equipment & testing. So, having "tuning' won't guarantee you will pass emissions, but also does not guarantee you will fail emissions -- the simple fact is don't expect the "tuning" to let you pass emissions just because you "tuned" it.

But hey, we're going to modify our vehicles, so how do we pass emissions and readiness tests?

It's very simple, as long as all your factory emissions equipment is working EXACTLY like stock, readiness will set, and if that is what your emissions test requires, you will pass.

Now what do I mean by exactly like stock? This means everything on the car, primary o2 sensor, secondary O2 sensor, EVAP system, etc, all work, are all *enabled*, and none of the codes these systems throw when they find a fault are disabled in the map. If the codes are disabled, the ECU will *NOT* set the readiness. Another fun fact, is EVAP readiness typically will *not* set until the catalyst system sets. So even if you have everything *but* the catalyst tests (secondary O2 sensor off or throwing codes due to HFC/downpipes/headers) working right, you may still have 2 systems that will not set readiness.

By default we disable the secondary O2 sensor in tunes because it *will* apply trims that screw up the mapping (particularly on vehicles with aftermarket downpipes). Modern ECU's use a wideband front O2 sensor, and the narrowband secondary O2 sensor as a sanity check for lean/rich conditions. When you change the downpipe to use an aftermarket cat or no cat at all, that reading is now SKEWED and not reliable.

In conclusion, it is not humanly possible for us to keep up with all the various state emissions regulations -- this is up to you. If you're worried about emissions and want a fast car, my recommendation is to buy a Corvette, Mustang or GTR. If you are modifying a car and are able to pass emissions still, awesome, let's build a fast car. If you're modifying a car and aren't worried about emissions, hell yeah, let's build a race car?
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Literally (IMO)

A county over they have no emissions. I guess I get it, but don't have to like it!!! We are a larger county and makes more of a difference in overall smog. I really am wanting to go catless :D my buddies claim "the know people" and can still get it done... I just don't want to have to sweat it and be SOL if I can't get the same deal.
Where are you located bro?
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