I fixed the vapor issue and it passed that part but I still failed on the actual emssions part. I did a tune up - plugs wires cap and rotor and it obviously needed it but I still failed NOX. My main cat is gutted - If I replace it will it clean up the NOX? here are the numbers from today.

My Reading today / last week / Allowable
HC 0.31 / 1.16 / 1.60
CO 4.65 / 6.49 / 15.00
NOX 2.63 / 2.57 / 2.50



My car failed emissions on two counts - this thread deals with a possibile additive.

My numbers are as follows:



My Reading Allowable
HC 1.16 1.60
CO 6.49 15.00
NOX 2.57 2.50



I have a couple of issues I need to resolve (I either have a cracked head or bad head gasket) I need to get it to pass so that I don't have to let the registration expire.


The other thing is that the shift kit in the Auto transmission is causing it to shift too early. Will that increase those readings if the engine is bogging?

 

Wow - Az compared to CA is pretty liberal. At first glance, looks like you're running rich - CO would be closer to 0 if combustion was better, but it may also have combustion temps that are too high, leading to excess NOX. That's generally an EGR problem, unless this is an idle only test. If that's the case, you may need to get the carbon off the top of the pistons or the miss condition is causing the ECM to subract fuel which is leaning out the other cylinders causing the high combustion temps. Hooking up a scanner and monitoring block learn would help you pinpoint it.

A leaking head gasket can create a miss. Check #7 for rust on the plug threads or an electrode that looks different than all the others. I don't know of any additives that are going to correct that condition, but mine, with a leaking head gasket, never had any problems passing CA emissions.

 

AZ uses a dyno with a varied course. I would guess that some of the unburned fuel is from the transmission being in 4th gear before it hits 30 MPH and doesn't come back out unless you downshift it by hand.
After I get the evap lines fixed I will have it tested again and have them keep it out of OD.

 

OD doesn't have anything to do with it. I just had mine in for it's biennial. Blew 15 ppms HC's and 0 CO at 15 and 25 mph with NOX at 160 ppm. A scanner that can capture 15 or 20 seconds while you drive it around the block can let you see what's going on.

 

NOx is created in the cylinders at high temperatures and pressures--auto companies in the '70s combatted it by lowering compression ratios and retarding ignition timing to reduce peak cylinder pressure. You're pretty close to passing on NOx, I bet retarding your ignition timing a few degrees would do the trick. Also make sure the car is warmed up decently so the catalytic converter is hot enough to work.

Good luck!

Ben

 

update at top of thread.

 

Can't anybody help?

 

Sorry Brookman, didn't realize you had updated this thread and didn't realize your main cat was gutted. One of the jobs catalytic converters do is convert NOx to N2 and O2 so if your main cat is gutted--I'd certainly think replacing it with a functioning one would solve your NOx problem.

Ben

 

 

Thanks for the replys - I just wanted to confirm what I was reading on the internet. As long as the cat is a three way catalyst - I understand it will change NOX to N and O2. I am going to order one tomorrow.

 

Yup, two-way catalysts process HC and CO, three-way adds NOx conversion to the mix. Btw, not sure if you've ditched your AIR pump or not, but even if you have it theoretically shouldn't affect NOx conversion in the catalytic converter. Also, as SunCr mentioned, a properly functioning EGR system reduces NOx--might want to make sure that's working correctly, too.

Good luck!

Ben

 

It is impossible to pass the IM240 dyno test without a cat. The old sniffer test, yes, but not the IM240 dyno, never, never, never.

 

And the suprise comes from where? The internet rumor that you can pass emissions without a cat is just that, an internet rumor.

Maybe some person some where found some idiot who didn't know how to hook up the equipment, or used faulty equipment and then squeaked by. From that point on it has been considered gospel.

Ever look at how expensive catalytic converters are? If you could pass emissions just by getting the tune on the car perfect then car manufacturers would do it.

 

Believe it or not, old coolant and bad flowing coolong system could cause Hi NOX. Try changing and flushing your cooling system. I have seen this occur several times.

 

I agree on both counts, high coolant tempp and a gutted cat ... I had to replace both of my cats as they were plugged... 580 dollars for rebuilts... not fun!

Mo