91FirebirdFmla

I'll try to make this short, I got my car inspected and failed the emissions test. This was due to a severly corroded cap and rotor and clogged fuel injectors causing an intermittent engine miss and skyrocketing HC and CO readings. The NOX was well below the failing threshold. In the process, I pissed of the inspection guy by informing him of how to properly jack up an F-Body.

I fixed the problems I found, which made the car run much better. I went to retest it but the guy remembered me and was very unpleasant. He tested the vehicle and told me that he could not give out a sticker, either inspection or rejection, because he was getting a diluted reading. He would not tell me what a diluted reading is, but said that it was either the machine or the car.

The only thing that changed on the car since the first test was the new cap and rotor, and a bottle of fuel injector cleaner in the tank.

I am assuming a diluted reading means that the sniffer is picking up too much oxygen which dilutes the reading, making the car appear as though it passes all of the tests. Can somebody confirm this?

Also, if it is my car, where could I look for a problem. I know my exhaust system is completely sealed. During the first test, the O2 reading ranged from 2-5%

Could the car have recieved a sticker despite the diluted readings, but not get one because the guy was angry?

And lastly, if I fail a second time, would disabling the EST which eliminates most of my spark advance improve my HC and CO readings?

Thanks

Joez88Camaro

O2 reading was from 2-5%? Tell him to screw himself and that the car has air injection and that it's perfectly normal to show that much in the exhaust.
The guy can get away with the diluted reading technically because that usually means exhaust leaks which cause the reading to be innaccurate (yes too much O2). I consider up to 3% to typically be ok in a vehicle with an old air injection system, and most techs don't care because it really can't hurt them in any way unless they're getting a surprise inspection, and even then it's really only bending the rules. The factory spark advace is 6' btdc, so you should be able to go as high as 9' legally to increase the burn time to eliminate some of the HCs and CO2 if NOx really isn't a problem for your car.
Also try a topend cleaning with seafoam, I've found that helps a lot if your concerned about passing smog.

1991L98G92

What state are you in?

Increase in timing = increase in HC, CO will not be affected.

Did you get an aborted test?

DENN_SHAH

iTrader: (1)

sample dilution detected, i have gotten that a few times.
i have never gotten a straight answer on it from the state, but my understanding is the machine sees too much O2 in the exhaust.

if the emissions testing where your at is like it is here in Texas & that comes up, there isn't anything he can do, the machine won't continue the test until it sees what it thinks is a good reading.

im wondering why did he need to jack your car up, is it so low he couldn't look under it?

91FirebirdFmla

I guess he wanted the wheels off the ground so he could check for play in the bearings, ball joints, and steering linkage. I'll get the car retested on saturday, hopefully everything goes well.

1991L98G92

If the CO2 is below 8.0%, OR, the O2 is above 8.0%, it is considered a sample dilution. Sometimes 9.0% on O2 is allowed. So it could be a CO2 problem. If the exhaust system is tight, either the engine isn't running as good as you think it is, or your AIR INJ system is dumping too much air into the exhaust. And he may have needed the wheels off the ground to check the EGR system. I usually just drive the car. to me it's easier than jacking up the car.

What state are you in?

91FirebirdFmla

I'm in Massachusetts. I'm not sure whether it was O2 or CO2 that was high, next time it gets tested I'll let you know. I'm pretty sure the test was aborted. I didn't get a print out of any results. Also, when the car was on the dyno, the inspector kept accelerating from 0 to an increasingly lower speed every time until the test stopped. What puzzles me is that it was fine a few days ago, except for failing, the car was still able to take the test, and all that changed was a distributor cap/rotor and the injector cleaner. So it may be the machine. If it gets a diluted reading a third time, i'll just take the car somewhere else.

Vader

What injector cleaner are you using?

91FirebirdFmla

I can't remember what brand the injector cleaner was. But I went back to the station last Saturday, and the guy told me the machine was still broken, and told me to go somewhere else. Which seems rude seeing that I would have to pay for the test at any other station instead of get the free retest at this place. Also considering that he had a week to fix the machine. So, I just left, and I'm going to go back this Saturday and if it still is not fixed, I will ask for my money back and take the car somewhere else, since he can't do the retest in a timley manner.

Also important to note, was that he was inspecting other cars while he told me this, granted they looked like newer cars.