328 emissions and what to change?

How good is the cat?
Philip

 

For that car to show 3+% CO ever......ever is wwwwwaaaayyyyyy wrong. It should be at (idle) about 1% without the O2 connected before the cat. At that setting it should show (all precat) 2% or less O2, 150 PPM or less HC, 14% or more CO2. When you plug in the O2 the CO an HC will drop even further. If you can't get those numbers your car is broken. If you can get those numbers leave it there, it will pass smog and make more horsepower. With a good cat it will show near 00 out the pipe. Some people don't get it, the cleaner it runs, the more efficiently it is burning it's fuel, the more horsepower it is making. High CO+high HC= LOW POWER. The math is that simple.


Lean the mixture, that thing is running fatter than Porky Pig. If leaning the mixture alone does not make the other # fall in line there is something wrong. Many times people run them rich to cover up other problems. Rich mixtures cover a multitude of sins but it costs HP. Bad cam timing is often covered by rich mixtures. Also some people believe they can do it by ear..Uh Uh No can do. Has to be done by machine.

 

Tillman:
If you read the Probst book and get a duty cycle meter (Actron makes a good inexpensive one) you can probably get the mixture set pretty well by using the DC meter in conjunction with your cars O2 sensor and ECU. Have not adjusted mine, but have hooked it up and studied it a little. I think it could be done fairly easliy. When checking my car the DC meter read inverse eg it read 75% when it should have been 25%. Not sure why this happens but others have had this occur too. I not sure, but I understand that in many cases when you have your mixture professionally adjusted they just use this method without ever hooking-up a four gas tester.

Mark

 

Much of Colorado also uses the dyno test. Unfortunately, ours are measured in "grams per mile" instead of PPM. However, at the last test my 328 my 328 had less than 10% of the allowable HC, 1/3 the CO and 1/6 the NOx. I have had 4 different Fcars take this test a total of 7 times and all pass easily. It sounds like something is defintely wrong. The only other thing I can think of is the motor was cold. Test needs to be done at operating temp.

Dave

 

Makes no difference how the dyno measures it. If the gasses are as I said it is running right and will pass. If they are not as I said there is a running problem. Reading all 4 gasses is required to make that determination.

 

If all you want is a duty cycle meter use a dwell meter,, same thing different name. That car should cycle between 45 and 55 %. On a 60 degree scale that will mean 27-33 degrees. Works great for a tune up when you know nothing is wrong and ignorance of the real situation is bliss. That does not describe this situation.