Another failed smog question

Ok I went to smog my XJ for the first time and HAHA gross polluter. So now i paid for a fail and he told me it needed a cat so i had a cat put on. Now for you smog guru's here are the numbers can you please tell me if it sounds right or will i drive in to give away more money to the smog man with another fail. Keep in mind these numbers are before the new cat, I have not been back after the install. 90 XJ 4.0

15mph co2 14.40 02 0.68 HC max 123 measured 81 CO% max .73 measured .18 NO(ppm) max 711 measured 1905 this was the gross polluter number

25mph co2 14.28 02 .65 HC max 103 measured 73 CO% max .93 measured .33 NO(PPM) max 613 measured 1436 this was a fail

So the NO was the failing number at both speeds which i think is nox this guy also said the 02 reading wasnt right or something
Any help or advice would be appreciated. Thank you in advance

You need to check your egr too.

Saudade said:

You need to check your egr too.

Click to expand...

Agree.

The EGR system reduces Nox.

http://www.asashop.org/autoinc/nov97/gas.htm

So, now you have to go a certified "gross polluter" smog tech. If they didn't tell you that, see if they are a GP station.

I was in the same boat ~7-8 years ago. I went through my entire emissions system. Found every leak, plugged every hole, got everything back to new condition. Since those are the numbers just for the running test, you could also fail on the cap pressure, purge (charcoal cannister connection/pressure the specific EGR test and the visual inspection, like if you or the PO by-passed/disbled/plugged the EGR or have some sketchy intake set-up.

Things to check and fix.

• Vacuum lines, replace (not tape or any other repair) any that are compromised. Vacuum runs several components including the EGR, MAP, Fuel Pressure regulator, so it's very important to have it all in XLNT shape. So your EGR might be fine but the vacuum to it or to the EGR solenoid might be cracked, leaking, missing, etc.
• Buy a NEW gas cap...You should replace your cap every 2 years if you want to live in CA., the DAY before you take it in.
• If the vac lines, including the set up from your fuel tank, are comprmised at all (including the roll-over grommet seals on TOP of your tank), you'll fail on that too.
• If the O2 is off, replace the sensor, especially if you never have, you only have one and it runs about $50. Your Jeep will thank you. I replace mine every 25-30K miles. I know it sounds like alot but my XJ currently gets about 18-20 MPG's overall in most all conditions.

So the best thing to do is to pay the DMV lisence/registration fees, they'll give you 30 or 60 days to fix it before you have to smog again. They'll give you a "redneck registration" or a red sticker to put in your window so the cops know you are legal.

I have been told by a Texas inspector, that running a fuel injector cleaner, 2 part system has always solved NOx (NO) only emission failures on vehicles here, where NOx was the only problem. The limits may be lower in California, but the limits you posted look pretty high (maybe Ca is easier on Renix jeeps limit wise, than HOs?)

The 2 part system is running a tank of gas with a good quality injector cleaner. The second part is basically running aerosol carburator cleaner in the throttle body while the engine is running, or doing a Seafoam cleaning through a vacuum line (instructions on the can).

You can check several functions on the O2 sensor your self, with a volt-ohm multi meter. See instructions here:

http://www.naxja.org/forum/showthread.php?t=1012701&highlight=oxygen+sensor+test+renix

A new O2 sensor might help, but run the tests to verify that the entire O2 sensor set up is working (verify feed voltages to the heater and sensor on the O2 sensor)

I would also test the CTS, MAP, and MAT sensors at running temps per:

http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

The EGR system could be part of the problem, but my money is on a serious carbon build up in the head and injectors making the NOx go way up.

Pull the spark plugs, inspect their condition, gap, fouling, color, maybe put in a new set of plugs if needed!

When you get done, share your before and after data here:

http://www.naxja.org/forum/showthread.php?t=966054&highlight=emission+test

...aaaannd, along the line of what EcoMike sez, run a can of G2P (guaranteed to pass) thru the gas tank, follow instructions on the can. If you fail, they'll give you your $6.95 back.