I'm having trouble passing the emissions test here in Texas.
The other numbers are fine but the hydrocarbons are a little high both
at low (15mph) and high speed (25mph) on the rollers.
For the last couple of years it just barely passed but not this year.
It is pretty much stock except for a K&N filter and Jacobs high energy
I just tuned it up because it was idling rough. I replaced the wires,
plugs, EGR valve, and O2 sensor. It tuned out the rough idle was a
vacumn leak, the little inline check valve was cracked.
After the tune up and finding the vacumn leak I was feeling pretty
confident about the emission test but I guess they saw me coming.
Any way I was allowed 136ppm HC at low speed and 139ppm at the higher
My output was 144ppm low and 149ppm. He ran it twice but no dice.
It may be my imagination but the exhaust does smell rich and burns the
eyes some when standing near it. I did not change the PVC valve but
it rattles when shaken.
Any help would be appreciated.
One of the easiest things to do is,
change oil and filter,and create a vacuum leak like pulling the pcv out
of the valve cover and just let it hang there.
Do this right before you go and make sure the engine is nice and warm.
I`ve done this many times,and has never failed.
Let me know how it goes.
1/4 Mile Junkies
If it runs lean it will pass the test.
You won`t have all that unburned fuel in there.
This was told to me by my mechanic. (good friend) I have passed at least
4 cars that way. I`m not saying it`s the right way,but it`s always
worked for me.
1/4 Mile Junkies
Get used to it, in NJ it's been around since the '80's.
Used to be a real pain on the carbed cars, even ones in good shape ya had
to pull the air filter out before pulling into inspection to pass. Had a
(gasp) '76 400 inch Cordova like that.
At least it gets rid of the junkers some folks drive that are running with
one dead cylinder.
Ya know, if it moves forward it's a safe car.
"Anything you say can & will be misquoted & used against you"
Fuel control looks to be good, air fuel ratio calculates out to
be 14.78 to 1 so doing as others suggest and creating a vacuum
leak will probably only make matters worse.
I'd concentrate on anything that would cause a miss-fire
including an over active EGR valve.
Did I say he was failing because of a mixture problem?
No, I did not. I advised that he look for possible causes of a
miss-fire. Miss-fires do not cause changes in stoichiometry.
What makes you think this truck has a carburetor?
(hint: he mentions replacing the O2 sensor)
Sorry just read this portion. I'm not saying your WRONG I wanted to know
why - I never questioned your judgement.
As for the carb bit, I looked at the year, again, the chart/your diagnosis
didn't have the O2 sensor anywhere in there AFAIK.
Watch it Buster.... 8-)
As for the "why," There is more to clean tailpipe emissions than
correct fuel mixture, i.e., you have to be burning it all + a
functioning cat helps a lot also. But a good first step* always
is to plug the numbers into a lambda calculator to see if the
fuel system has proper control, rule out a fuel problem and then
go after the cause of the failure.
(* that's why I asked for all the gasses)
His mixture is -slightly- lean but not enough in my estimation to
be the root cause of his HC failure.
I found 2 tests from 2 different cars.
These both passed just like I said from my previous messages.(oil,pcv)
Just wanna show you the bottom line.
Can I send you an e-mail for what I have?
1/4 Mile Junkies
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