Colorado Emissions

Well, when I first did the swap I had the car inspected by the state and it passed as well as emissions tested (the completed the idle and 2500rpm test) and it passed. Fast-forward to today and they completed the roller/dyno test and it failed. Here are the numbers:
Motor is a 2001 LS1 with long-tube header, magnaflow spun cats, full 2.5" dual exhaust.

HC GPM 8.1823 (limit is 1.20)
CO GPM 17.6757 (limit is 15.00)
CO2 GPM 425.7080 (no limits)
HOx GPM 3.0047 (limit is 1.50)

Also failed the check engine light, but shows no codes. (Maybe check engine light couldn't be forced on)

Passed car presence, air injection system, O2 presence, and gas cap integrity.

Any ideas...Seems that the motor is running way rich and fuel is not cutting.

Thanks for any suggestions.

Royce

Even the slightest debris in an injector will cause rich condition. You already have low O2 working against you at high elevation. Assuming all ignition components are good and timing is correct, I suggest adding 5 to 6 oz. of Acetone to 10 gallons fresh gas and running it 50 miles before you test again. I've never had any vehicle fail with this method.

If you can get access to your fuel trims, you may be able to figure out why you are running rich. Short term Fuel Trims are a good indication why your motor is running rich or lean. For example, positive fuel trims indicate your PCM is adding fuel due to your O2s reading a lean condition, negative fuel trims indicate your O2 are removing fuel because O2 are seeing a rich condition. If the car has run well for a while then it probably isn't your tune problem, its most lightly failing O2s, fuel injectors (leaking) or an exhaust leak, exhaust leaks suck in extra air that O2s see as a lean condition and tell the PCM to add fuel (positive fuel trims).

Take a look at the attached link, it has some information on testing O2s sensors, this worked for me we I once bought some used O2s.

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I just went through this battle.

#1 is to check your tune and make sure nothing has degraded that's effecting the way the car runs. If the ECU is compensating for something by throwing fuel at it, your gonna fail

#2 The Magnaflow cats are garbage. When new they're decent enough to pass, but once you've put some mileage on them they're totally ineffective. Mine were basically new (I run test pipes on the track) and I couldn't pass with them. A new set of cats that were twice the size did it.

I'll drop you a note, I just put my car through all this...

I have found that my passenger side exhaust gaskets at the collector/exhaust pipe junction are leaking and because the pass side O2 sensor is downstream of that junction the air getting into the exhaust pipes at the leak is making the O2 sensor pick up a false lean condition and that tells the PCM to dump a lot more fuel into the engine such that I'm running really rich.

Doc...Any help would be great.

I don't have anything to check or change the tune.

What cats did you use to pass? I have 8 days now to retest.

Thanks!

I've got a pair of the large, 3" magnaflow dual core cats. The little bullet cats that were there before just couldn't get it done. Even though my old cats were basically new, they weren't efficient enough to get the car to pass.

The new cats were perfect and work great.

I also went through the smog certification process, that was a real PITA. The car had everything they wanted to see, but it took me awhile to figure out how to get all the readiness monitors to read "set" so they'd be happy.

Now the car gets tested as a 2002 Camaro SS...

Yeah, mine went through the certification process right after the swap was completed.

It passed all the equipment, failed the check engine and failed the emissions levels across the board. When we had it dyno'd, I think I remember it running rich on a few pulls.

Don't really want to throw more money into it but maybe cats would make the difference.

Check your ground going to your check engine light. Mine was always popping off, rendering the light inop. I've now wired the "!" in the instrument cluster as my check engine light.

You need the cats. Trust me, it's just not going to pass without them. I'd also suggest having them bolted in place and a set of test pipes made. Once you pass, remove the cats and put in the test pipes, the aftermarket cats just don't last very long. If you drive any amount of distance with them over the next two years it's iffy whether they'll be effective enough to get the car to pass again.

Just put the car thru some tests and they said it was dumping fuel when letting off the gas. I should have graphs later to post when they email me. The tune is stock...guessing either decel fuel cut off (dfco) is not working or a bad tps. Either way, cats are shot as well.

How can I determine that DFCO is enabled in the tune? All that should be disabled are the vats and tranny codes.

Not sure what tuning tool you are using, for HP Tuners it can be disabled by increasing the enable temperature to a setting that the motor can never reach. I would find a stock tune and compare the fields, I tune in EFILIVE that is very different but the concepts are the same.

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I believe the tune is stock with the vats and tranny codes turned off. I know HP Tuners is used by Eric but my LS1 is stock besides the long-tube headers, spun cats and intake.

I can pretty much guarantee you that the cats are bad.  I barely ran mine as I mostly ran test pipes and they couldn't scrub enough emissions to get me to pass.  Once I replaced them with much larger, dual core cats the car passed easily.

Well, brand new cats installed yesterday and took it in for an emissions test today and still failed HC readings but all others passed great.

Here are the numbers now:

HC GPM: 2.3495 with a limit of 1.2000 FAILED
CO GPM: 5.8206 with a limit of 15.0000
CO2 GPM: 474.9266
NOx GPM: 0.0585 with a limit of 1.5000

Will simply adding acetone (4-5oz) to a full tank get me to pass??

Hmmm, you might want to put in a gallon or two of E85 and see what happens...

6oz acetone and 10 gallon of 100% petro. The ethonol blends can only be trusted if you are 100% sure that NO water has been taken up from the storage tanks to the gas pump as it is highly hygroscopic.

curious, what does 100% petro mean in terms of octane level? or do you mean any octane just no ethanol blend of any kind?

No ethanol and whatever octane% your engine calls for. The only time I've seen this method not blow great HC#s is when leaky valve seals or shot piston rings were involved.

Problem is everything around here has 10% ethanol added. It's an almost full tank right now, would adding the acetone right now and driving 40-50 miles before testing help my hc levels?

Impossible to find around here too, everything is 10%, except race gas!  

Burn the current tank down to almost nothing, add a few gallons of E85 and see what happens.

xschop wrote:The only time I've seen this method not blow great HC#s is when leaky valve seals or shot piston rings were involved.

I've been reading that leaky valve seals are a common problem with the Lsx.

I'm having my leaky valve seals replaced right now

Doc, who are you taking your car to? There is not much up north....I'm going to try the e85 or ethanol to get it to pass for now as I'm running out of time.