bruceqmed

Just passed smog. First station failed me, NO (PPM). 15 MPH MAX 437-AVE 16- MEAS 581, FAILED. Take to second shop to have work done, they just put on machine no work done, PASSED. 15mph- MAX 437- AVE 16- MEAS 362. Most readings high side. Shop wants to do tuneup, fuel system clean, and check strength of sensors. CAR, 04- 31,000 MILES- OWNED CAR 7YRS PUT ABOUT 1,000 MILES ON IT PER YR. READINGS HIGH SIDE BOTH 15 MPH AND 25MPH. SHOP SAID HIGH READINGS COULD BE HARD ON CATS OVER TIME. (OPINION) What does tuneup cosist of. No check eng light. Car stock - stock tune - KN air filter, just filter not KN setup

4XLR8N

Here is what I would do:

Make sure air cleaner is clean, replace if necessary. Clean MAS. Then run a bottle of techron through it. If you want to go the extra mile, replace the spark plugs and wires.

With no codes, and assuming it runs fine, I wouldn't go any further than that.

bruceqmed

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bruceqmed

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bruceqmed

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bruceqmed

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drseth

The Oxygen Sensors may need to be replaced. Time can deteriorate things almost as much as actual high mileage use. The PCM reads the O2 Sensors and leans or enriches the fuel depending on what the O2 sensor tells it.

bruceqmed

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chuckeb84

Replace the front O2 sensors
Clean the MAF
Plugs and wires
CAI clean

Optional PCV and Gas filter

Zip's tune up
http://www.zip-corvette.com/97-04-c5...y-tune-up.html

Biotex

Kind of sounds to me like you are not letting the car get up to temperature for a longer period of time. Only 1000 mi/yr? Do you treat the gas? Also seems like it could get stale, not burn efficiently.

I'd go for a long trip to burn out all the old gas, fill up with new, retest it.

madmatt9471

Plugs: NGK TR-55 (gapped at .055)

Wires: MSD Red (or any color of your choice)

New Air Filter: Paper replacement or K&N

MAF: Clean with a proven MAF cleaner - proper way to clean it to remove it off the vehicle and clean allowing any debris or build up to be removed, let dry and re-install (Follow the instructions on the Can)

O2 Sensors: At 30,000 miles I would not worry about them

Injectors: You can run some Techron Injector Cleaner or Some Seafoam Treatment in your fuel tank (At 30,000 miles I would believe they are not in bad shape, unless you got some real bad fuel)

Fuel Filter: at 30,000 it would be a good and easy change to do

You can order most or all of this stuff from JEG's or Summit Racing and most can also be obtained from your local auto parts store!

Plus, this is something you can do yourself with ease and save!

Thanks,Matt

bruceqmed

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baxsom

1000 miles a year?? Its a car not a museum piece. I do twice that just getting back and forth to work every day in mine.

cvm

Is car stock w/ stock tune? failed for NOX (NO?)which can lead to a higher than normal combustion temp situation. Cant form until over 2000* or something. Try a carbon treatment- carbon in combustion raises comp.ratio; make sure plugs are correct, not for modded eng. and car running @ correct temps. Most of all don't throw parts at it *****-nilly. This aint a sensor. A bad cat can cause this cuz 1 cat function is to rid exh of NOX,
Find a real mechanic . GL!

Did you get HC & CO readings too?
Ever have lean codes w/ this car?