Emissions issue on 1987. 350 w 700R

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

Can't offer help without the other gas readings; CO CO2 O2 NOx

Am I the only one who thinks it's sad that Texas has a smog test, land of the baboon (boosh)?

~KJ~

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.

All of the readings are as follows: High speed 25mph and low speed 15mph

HC(ppm) High speed Std 136 Reading 144 Low Std 139 Reading 149 FAIL CO % Std 1.66 0.20 1.24 0.23 PASS C02% 14.6 14.6

02 0.4 0.4 NOx(ppm) 1786 468 1916 472 PASS Dilution% >6 14.8 >6 14.8

I take it your saying to let is suck some clean air for a few minutes before they run the test?

Answers to questions like this or any other tips would be appreciated.

The PVC valve will cause a vacuum leak and make the vehicle run lean.

~KJ~

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.

That's ridiculous. 14.7:1 is the theoretical ideal mixture (from a carb no less) and he's failing?

~KJ~

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.

~KJ~

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.

His first post mentioned having replaced the O2.

That`s exactly right! Leave the PCV out during the test.It will suck in lots of fresh air.

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

Ken, 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

Sure thing. My email is snipped-for-privacy@oplink.net