High NOX means bad cat.
--- In ev_update@..., "Ian Mothersill" <imothers_2000@...>
wrote:
Hello all,
The short version is, what do you check if the NOx is too high (and CO
is close to being too high) to pass the smog test?
A while back I failed the Vancouver-area "Aircare" smog test with very
high CO and HC readings (posting #103838). Turned out the blue 2
wire temp. sensor wasn't plugged in properly, so I was running in
default rich mode. This happened when I was diagnosing "no starting"
problems. I burned about ?? tank of gas with the sensor unplugged.
Plugged it back in, and the van ran better and didn't smell of gas.
So I waited for a couple of tanks of gas, some around town and some
highway driving, then went back to re-test. I also installed a 470
ohm resistor in the circuit to the Intake Air Temp sensor; haven?€?t had
any instances of high idling since then (something that happened from
time to time before). This time, HC and CO are OK, but NOx is higher
- high enough to fail.
Plugs, Cap, rotor, and wires are all new.
The readings on the first test were:
|max Allowed | reading | Avg. Pass
HC | .9900 | 1.6849 | .3049 >> FAIL
CO | 12.43 | 36.8187 | 6.1019 >> FAIL
NOx | 1.5500 | 1.2423 | 0.7272 >> Pass, but higher than
average
The readings on the second test are:
|max Allowed | reading | Avg. Pass
HC | .9900 | 0.6051 | .3049 >> Pass, but higher than
average
CO | 12.43 | 11.1820 | 6.1019 >> Pass ?€" barely!!
NOx | 1.5500 | 1.7398 | 0.7272 >> FAIL
I seem to remember that high NOx is often a catalytic converter gone
bad. Is that the case? Anything else to check out, such as the
Oxygen sensor? Timing?
My van has a ?€?generic?€? converter that was put in a couple years
ago by
a previous owner. The front pipe that comes with the ?€?factory?€?
converter is wearing through, so if it is the Cat I can kill 2 birds
with one stone on this.
Thanks.
Ian Mothersill
93 EV Weekender 5 speed
Vancouver, Canada
