Help with passing emissions in TN

[1Byounkin]

I have a 91 explorer. Last year I had trouble passing the TN emissions because of high HC. Rebuilt the engine, valves and all. Doing that made the HC to 64 and passed. Now again this year it failed again. Put new wires and plugs. Clean the intank, TB, MAF, IAC, intank air temp sensor. Checked for vacuum leaks, none. The engine ran alot better after new wires. 18+mpg. Was at 15mpg.
The readings I had before (for this year) the new wires- HC 1360 - CO .064% CO2- 5.95%.
Went today to retest. Drove 50+miles. Tried to get it tested again and failed again for the readings being too low. CO-0.01% CO2-4%. Nothing showed for HC. They said that the exhaust pipe was old and needed new pipe for leak. All of that is new. That said it had a miss, There is no miss every plug fires the engine idle smooth at one speed. They said the engine idled to low to test. :scratch: But the idle is at 600 rpms and controlled by the computer. The computer has been resetted after cleaning everything and drove it to relearn.

Anyone have any ideas to get the numbers up to pass.
No CEL.

 

[willindsay]

Didn't know there was emission testing in TN... We don't have it here in Sevierville.

 

[1Byounkin]

Around the Nashville area and the county's that touch Nashville. I'm in Sumner Co. Basically obd I get the tailpipe and cat check. If 1996 and newer than a computer check with no tail pipe check.

 

[willindsay]

Good to know... Won't be moving anywhere near there then my car wouldn't come close to passing.

 

[Yankee516]

Sounds like you cleaned and replaced everything, but what about the O2 sensors? Didn't see that mentioned anywhere. Could you also bring the car to another inspection station? If in doubt, maybe the local Ford dealership can do the inspection and provide some knowledgeable feedback on the car. If TN is like NY, the price of an inspection is fixed so you shouldn't get hit too hard with the cost.

 

[1Byounkin]

I did the O2 senser 3 years ago. I'am going to take the truck to a different location to get it tested. Price here is $10 if you fail you keep getting retest with a refund until pass.

 

[Roadrunner777]

Your county should have a process to review inspection station issues, and some way to mediate/resolve them. You may have to do some hard looking and maybe drive to your county seat and ask around.

 

[Iron Weasel]

High HC (hydrocarbons) are a result of unburned fuel entering the exhaust system and generally caused by poor fuel ignition in the combustion chamber. A bad catalytic converter can also cause excessive HC readings as well.

This site has a more detailed explanation.

If all else fails, you can use the old trick of running your fuel tank down to almost empty, then putting about 3 - 5 gallons of high octane fuel along with a couple bottles of isopropyl alcohol (like you find in a drugstore) and then sticking it on the sniffer. It probably won't run very well, but it will give you a better chance of passing.

 

[runningred92]

I live in Nashville and had the same problem you have. I drove it down 24 to Murfreesboro and back and had added 1 bottle of alcohol at about a quarter tank as I was getting back into town and it did run a little rough but drove it straight back to the testing station and passed. I went to the same station and had the same guy do the test in the same day so I am pretty sure that could work for you. I went to the test station on Antioch Pk. @ Harding Pl. good luck

 

[Robert Nick]

I agree go the Antioch Inspection Station. They are not picky like other stations I have been. Hopefully you will pass the Sniff Test. Do the Alcohol thing just prior to the test.

 

[CDW6212R]

Interesting, the idle is too low and the pollution readings are too low, so that's a failed test? What morons came up with that logic. It doesn't make enough pollution for the given vehicle, fix that. I can't believe that there is a minimum limit.

Raise the idle, 700rpm is good for the V6. Play with the TB and TPS, clean and adjust as can be. You don't want to mess with the idle screw, unless you have to and the TPS idle voltage is within specs(close to 1.0 volts). Check them before you alter the settings, so you can know how to return them if needed. Clean the IAC well before you do that too, that means clean the seat where the plunger sets between the two sides. That's where it matters to have it clean.

Good luck.

 

[Iron Weasel]

Clean the IAC well before you do that too, that means clean the seat where the plunger sets between the two sides. That's where it matters to have it clean.

Some IAC motors can't be cleaned.

Easy way to tell if yours can be is it look for two screws holding the two halves of the motor together. If you see the screws, that motor can be cleaned.

 

[1Byounkin]

I finally passed emissions. I ended up tearing down the engine again to find three intake valve leaking. Which was two seats and one valve guide. So now I have new stuff from the heads up. Even new injectors. Cleaned all carbon off of everything. Run a whole lot better. The HC was at 189 now after the work.

 

[Robert Nick]

Glad you finally got through the Test. You have alot of miles on that engine. I am at 158k, only one cracked head and a A4LD Rebuild.

 

[Burns]

Look at all the people from TN lol


Glad you got it to pass. Im so glad we dont have that in Sparta

 

[mr cribb]

Didn't know there was emission testing in TN... We don't have it here in Sevierville.

just in the metro Nashville area.... We don't have them in Clarksville either

 

[mr cribb]

Look at all the people from TN lol


Glad you got it to pass. Im so glad we dont have that in Sparta

LOL there's a few of us and then some....

 

[1Byounkin]

I'm not sure the true miles on the engine. Cleaning the pistons I found that they have been bored to .20 over. So the bottom end must have be rebuilt before I got it.

>Burns did you see my PM?

Lets see if anyone else is from TN.

 

[mr cribb]

I'm not sure the true miles on the engine. Cleaning the pistons I found that they have been bored to .20 over. So the bottom end must have be rebuilt before I got it.

>Burns did you see my PM?

Lets see if anyone else is from TN.

I'm "technically" not from TN but it IS very beautiful here. I'm just stationed here. I actually begged to come back to this area on TN.

 

[DasBaldDog]

I WAS from Memphis. Live in PA now.