Failed NYS Emission inspection...help

[bagelluvr]

My 87 corvette failed inspection for the following Emission results:

Vehicle reading / Limit

HC 1.76 / HC 0.80
CO 74.66 / CO 15.00
NOx .21 / NOx 2.0


I now have 54K on the car with only 3k miles driven since last years inspection. About 10 months ago I changed the rotor, cap, wires, plugs and cleaned the K&N filter. The shop that did the inspection said I should give it another tune up. Can the catalytical converter be shot? Any suggestions?

 

[grapeknutz]

Change the O2 sensor first and keep the hood closed during the test to keep the heat in the engine.

 

[G Winter]

has the look of a rich mixture. .. which could relate to the O2 sensor or a leaky injector.

 

[bluecoupe]

Take it to a Corvette Specialist:
I've heard good things about Vette Doctors on Long Island.
http://www.thevettedoctors.com/htdocs/general_repair.shtml

 

[Edmond]

Take it to a Corvette Specialist:
I've heard good things about Vette Doctors on Long Island.
http://www.thevettedoctors.com/htdocs/general_repair.shtml

Good idea. Let them diagnose the problem so you're not throwing money at the car.

The high readings are the result of running rich. All the reasons listed above can cause high emissions readings. I hope the Vette Doctors can pinpoint the problem so you can fix just what needs to be fixed.

 

[SPANISHVETTS]

You can put the ECM in field service mode to see if the O2 sensor is working or check it with a volt meter. The field service mode will also tell you if you are going into closed loop. Do a search on the forum for more info on this.

Be sure that the car is at operating temp, (in closed loop), when they sniff it. Thunder would not pass emissions in Timbuktu cold but when it is up to temp it sniffs cleaner than a stock L98.

 

[Achilles]

I had a car fail emissions once and the tech asked me if I drove the car much and how far I lived from his shop. I lived only a couple miles away and didn't drive the car much at all, maybe less than 1k a year. He told me to put some injector cleaner in the tank and go drive the $*it out of it for a few days and bring it back for a retest. Also, he said to drive it for about 30 mins. before bringing it in for a retest. It passed! Whatever that means

 

[larryfs]

those readings are NOT from running rich, they are from a BAD EGR.

 

[grapeknutz]

those readings are NOT from running rich, they are from a BAD EGR.

Not really, it would throw a code and the idle would be rough.

 

[bagelluvr]

the results are in!

I picked up my car and the root cause of it failing the inspection is......
a bad relay! The MAF sensor relay that burns off the wire on the wires. The new value for the CO went from 74 to 3! Keep this in mind if it ever happens to you. Thanks for all your suggestions.
Greg