Emission Inspection

[Muddy]

Emission Inspection

I put my 92 vet through the Texas State Inspection, twice and unfortunately failed both times (on to high HC, CO and NOx ). Before the second inspection I added RXP (an Engine de-carbonizer) to my gas and the readings dropped a bit. I have been in contact with the manufacturer of RXP and was advised to run a full tank of gas with RXP added. Oh ya I used Chevron gas.

Has anyone had experience using the RXP gas additive?

Is there any way, using the OBD port, to determine if I have problem in the emission control system.

Does anyone know the value or where I could get the standard values for the HC(ppm), CO(%) and NOx(ppm) for a 92 Vette, for Denton Texas? My vehicle inspection report says standard CO level is 0.65% to 0.67% which seems a bit low to me. :confused

Cheers
Muddy

 

[boblx2a]

Sorry you are having DEQ trouble that is a real PITA. But to speak to the 2nd part of your question, most scan tools will only give you a "go no-go" indication. You may need a diagnostic type tool to help you with DEQ problems. They can get pretty spendy, I have AutoTap which costs about$500.00 for the model that covers all makes. They get even pricer then that. It would be neat if you could borrow one or have someone run it for you. It would probably indicate what was wrong because it lets you know what the readings normally should read as opposed to what they currently read.

The other thing is did you take it in there very hot? I have learned that the DEQ in Oregon is passed most times by cars when they are very hot. One time I was sitting in line and I kept turning my engine off to conserve fuel and engine wear and tear while i waited. I failied the test! The operator knew what I had been doing and he said to go back to the end of the line and this time leave it run. That time I passed.

Good luck with it.......

 

[Muddy]

I was talking with a friend today and he mentioned was the car at normal operating temperatures. I seam to remember it was about 120-130 water and 170-180 oil. It was a cold day about 45 but I think my thermostat is not working correctly. My heater in the car is not very hot, this is the first time I had to use it.

What is the normal operating temperature for a 92 Vette and what temperature rated thermostat should I get?

Cheers
Muddy

 

[boblx2a]

Well I don't have a '92 Vette but I am certain it should run warmer then 130 degrees. If that is what yours is running that is a good reason for it to fail emissions. My '85 and my '86 always ran at least 190 and much warmer sitting in a line waiting for an inspection, more like about 205 or so. A cold engine will not pass emissions in the state I live in. That has been proven to me. I bet your thermostat is stuck open or at least leaking quite a bit.

............

 

[BigRed]

Theres your problem right there. (Assuming all other sensors are reading properly)

Ive been learning about these systems in my new shop. From what Im taught your car is in whats called "Closed Loop" Which BASICLY means you've got your choke on (Carb talk). Change out the thermostat with a 195 F (Not sure on C's) This will allow the engine to reach its desired operating temperature and will allow the "choke" to release. Or in proper terms engage closed loop.

See, understand when you turn on your car the engine runs RICH purposly to get up to "safe" operating temp, your car is just not leaving this stage. Actually you can do a couple of things.

Put in a Hypertech Chip with a 160 degree thermostat and try for a little Hp's (costs a bit)

Or simply change out the thermostat you have to a stock issue 195.

BTW try to buy AC Delco on this, go right to the dealership for your thermostat. We have found that 1 in 4 thermostats off parts shelves are defective. (which will drive you nuts) Versus Dealership's at 1 in 10. (hey its about 2-3 dollars difference)

Hope that helps you out.

 

[boblx2a]

I completly agree with Bigred on this. With water at 130 degrees you are definately running in closed loop mode which would really make your emissions suck! I think my '85 goes into open loop mode at about 145 to 150 degrees. Don't quote me on that, it has been awhile since I had it on the computer but it for sure is warmer then 130 degrees.
I also agree on buying parts from the dealer. Anything that can leave me on the freeway I buy from the dealer. I have had enough rides home on the back of a flatbed because of 3rd party parts. You may however have a problem getting a 160 degree thermostat from the dealer. All most of them carry is the stock thermostat although you may find an exception.

Good luck with it..........