Failed California smog inspection. Any suggestion?

[E30 Cabrio]

Failed the "15 MPH" test for NO (PPM)
MAX: 785
AVE: 342
MEAS: 950

Also, my "25 MPH" test for NO (PPM) was on the high side:
MAX: 724
AVE: 272
MEAS: 640

HC (PPM) and CO(%) were over the average but under the limits.

Any suggestions?

I removed my aftermarket chip and put the stock chip back in, changed the oil and ran a tank full of "CRC Guaranteed to Pass" snake oil recently.

[KenC]

High NO is from a bad cat.

[Bey]

How's your cooling system? Did you have it flushed recently? High NOx doesnt always mean a bad cat.

[E30 Cabrio]

How's your cooling system? Did you have it flushed recently? High NOx doesnt always mean a bad cat.

The cooling system is good, but my Fan Clutch is failing and the car is running a little over halfway on the temp gauge when idling.

I have another Fan Clutch on order.

BTW, the car has 125k on it.

[bzboardz]

i failed on 87 ran a full tank of 91. tried again and passed

[E30 Cabrio]

i failed on 87 ran a full tank of 91. tried again and passed

I'm also running 91 Octane.

[KenC]

Make sure the car has been running for a while before you go in. You want the cat to be nice and hot.

[Rodoni]

Welcome to the club, lol.

Seafoam, drive it hard before testing (don't just drive it), denatured alcohol works, and everything else people already mentioned

[tjts1]

The cooling system is good, but my Fan Clutch is failing and the car is running a little over halfway on the temp gauge when idling.

I have another Fan Clutch on order.

BTW, the car has 125k on it.

Fix the fan clutch and get a new O2 sensor. Drive the snot out of it before the test.

[Cabriolet]

this the cat. get a new one and you'll pass easily. my 1986ES had almost the same numbers. new cat. was less than 1/10th the numbers

[tjts1]

this the cat. get a new one and you'll pass easily. my 1986ES had almost the same numbers. new cat. was less than 1/10th the numbers

You probably wasted your money. A new cat can help hide a failing O2 sensor but not the other way around. The O2 sensor is the first thing to replace because Its much cheaper and more likely to fail.


Before and after replacing a $44 O2 sensor on a 175k mile car with the original cat. Nuff said.

[Cabriolet]

ya i had just changed the O2 sensor, was trying to go the cheap way. i was high in HC and CO, though.

but defiantly change the O2 sensor first

[freeride53]

alternator? mine failed it, then chris at german auto sport got it to pass...

[Uber E30]

Before you buy anything i would drop the midpipes and look for any holes. Those numbers are typical of a leak. If you dont want to drop the pipes you can put the car on stands and turn it on, then feel around for any leaks. Care not to touch the pipes though as they will be hot!

[Jon325i]

I'm surprised no one has mentioned going over the ignition system. Plugs, coil, wires, cap/rotor. If any of these are in bad shape, it will hinder the efficiency of the combustion process....ECU tries to compensate for it and there goes your numbers. At the very least pull the plugs and inspect. If you're not sure of their age/mileage, replace them. Another cheap fix.

Jon