1992 Camaro Z28 5.7L (rebuilt as of 1 1/2 years ago), brand new injectors, brand new igition, wires, distributor and cap, as well as plugs.

Car was tuned up by the dealer 3 months ago) and getting the best gas miliege i've ever received on my car.

I normally drive WITHOUT cats (Comes factory with 2 cats with airtubes). Today I went to muffler shop and had BRAND NEW High Flow (3" reduced to 2 1/2 installed with flanges) as I only want to pass emmisions and then will pop back the straight pipe after passing.

The muffler shop only installed 1 of the airtubes to the cat and left the other cat's airtube unconnected (the line from the car was taken off due to it rattling against the frame of the car when the straight tubes were there and the tubes were just hanging there.

They claim the car only needs the 1 airtube hooked up.

[EMMISIONS TEST]

Drive 30 mins to aircare facility. Car was not turned off and the engine temp was showing around 60-70degress (Assume Farenghiet due being in Canada?).

I was SHOCKED to see that I failed?? With all new stuff, how would I fail??? But I only failed Hyrocarbons and by 0.05!

[FAILED stats]


HydroCarbons (Max Allowable: 0.5000) FAILED at 0.5501
Carbon Monoxide (Max Allowable: 9.3200) PASSED at 4.6974
Oxides of Nitrogen (Max Allowable: 1.2400) PASSED at 1.0977


[PASSED: 2010]

HydroCarbons (Max Allowable: 0.5000) PASSED at 0.3287
Carbon Monoxide (Max Allowable: 9.3200) PASSED at 2.2016
Oxides of Nitrogen (Max Allowable: 1.2400) PASSED at 0.8603

Now my questions are these because you'll notice that in 2010 my stats were MUCH lower (car was running lean, needed tuneup and cats) than with the rebuilt engine, new parts, brand new cats.

1. Does the readings look like I need to just change the O2 sensor?
2. Obviously nothing to do with cats, HOWEVER what about the fact that only 1 airtube was hooked up, would THAT be a cause of this failure?
3. Or could it simply be the cats were hot enough and can just fork out the $23 for a retest and it was likely just the cats needed to be warmed up more?

 

You lost Hp when you went to single cat. You car is a G92 car which means the rated Hp is 245hp. Single cat is rated 235hp. IMHO go back to dual cats and you will pass smog and gain back your HP.

 

Hello Vincent: I think you misread my msg. I never said I went to single cat :-)

I had typed that I normally go with out cats (just the straight thru piping) but for aircare I had brand new cats (2) added back but flanged in so I can replace them with single tubes once I pass aircare.

The part I notice was that only 1 of the 2 cats had a line to the airtube. both have airtubes like in stock, but they only hooked up 1 airtube; the other cat has the airtube unhooked.

 

Ok my bad! Just hook up the other air tube and you might pass because the other cat is not getting as hot as the other one.

 

Since the airtube that is not connected is because they didn't want to get another tube (it was broken off right at the seam that is connected to the car), they only hooked up the one.

do you think that I just need an O2 sensor, or could run the car on the freeway for 30 mins or so and just get the other cat to heat up (without the airtube hooked up)? Otherwise I will be paying to have a new airtube installed only to have cut off right aferwords and then trying to figure out how to stop it from SHAKING against the frame of the car once it's cut off onto the cats.

I have 3 choices:

1. Pay more to get airtube welded on (they might need to buy another airtube since it's broken off and gone from the seam) only to be cut right off again when the cats are both removed and replaced with the dual pipes..

2. Run the car longer on the freeway to heat up the none-air tubed cat

3. Pay to get o2 sensor and then try again.

 

How about using a thick rubber hose. If no check engine then don't get an O2sensor but you can take off the O2 sensor and clean it with carb cleaner. Get a can of Lucas Octane Booster. It works too.

 

Problem FOUND!

Turns out that everything that would NORMALLY cause problems with aircare are perfectly fine, as I would so think seeing how they have all been replaced 1 1/2 years ago and a brand new set of cats.

Turns out that my FUEL was leaking above the fuel tank which is how they explained was the reasoning behind why the LONG drive on the freeway which would have normally reduced ratings INCREASED the rating literally off the charts!!

He said he noticed a very strong gas smell when the car was hot (I too noticed by assumed it was because I was at the time before running NO cats). He took a sniffer and discovered fuel vapor spitting out of the top of the gas tank at a hose or something..

I also am ordering a brand new ACDelco A.I.R Injection Line and thinking I may put threads on the end of the elbow AIR tubes off the cats and thread the airlines into them when it comes time for aircare rather than welding, cutting, welding..

 

It's extremely unlikely that a leaking fuel tank will effect readings on a sensor inside the tailpipe.