Failed Smog Check: 1996 Toyota Camry High NOX at 15mph, good at 25mph - Toyota Nation Forum : Toyota Car and Truck Forums

J_Gee · 10-18-2010, 10:56 PM

1996 Toyota Camry 4 cyl Front Wheel Drive Manual 130000 miles

My car failed the CA smog check. The following are the results:

15mph: %CO2 = 14.7; %02 = 0.3; HC (ppm) = 14; %CO = 0.00; NO (ppm) = 1297

25mph: %CO2 = 14.9; %02 = 0.0; HC (ppm) = 8; %CO = 0.02; NO (ppm) = 84

I checked EGR by applying vacuum at idle => stalls car.
The car has new platinum spark plugs and has no other problems.

What can cause bad NOX at 15mph, but fine at 25 mph? All other emissions measurements are fine. Please help!

rusty9 · 10-18-2010, 11:02 PM

catalytic converter.

Nervous · 10-18-2010, 11:02 PM

catalytic

***LynchburgCSI*** · 10-18-2010, 11:09 PM

I'm also gonna vote for the cat.

***fenixus*** · 10-18-2010, 11:26 PM

I wouldn't jump out on cat just yet as the CO levels are minimal and usually broken cat causes LOTS of other symptoms (poor engine performance, rpm cut out at higher engine speeds, etc.)

mostly ONLY NOx levels get crazy high, so EGR sub-system to be checked first per FSM.

***LynchburgCSI*** · 10-18-2010, 11:28 PM

^ I was just glancing over the FSM to be sure... you beat me to it.

***fenixus*** · 10-18-2010, 11:29 PM

Quote:

Originally Posted by LynchburgCSI

^ I was just glancing over the FSM to be sure... you beat me to it.

TRD95 · 10-19-2010, 01:11 AM

My car failed the same way last year

turned out to be a bad EGR Valve (even though it tested good). The CO levels do look good, so I would also rule out cats. And it being a 96, I'm sure cats for that model would be hella expensive! Hope you find a solution soon buddy!

***fenixus*** · 10-19-2010, 01:14 PM

yeah, unfortunately EGR valves tend to go bad over time as they get dirty with soot/carbon... and the way we all test them quickly (pull vacuum on running engine to see if it stalls) is a half ass test proving really nothing except the rubber diaphragm not leaking vacuum... still the valve can be very dirty at bottom causing it to either unable to fully close or get fully opened when needed.

I had to replace mine for the exact same reason even though it passed the mentioned testing.

Jason.MZW20 · 10-19-2010, 01:54 PM

Yeah, I'm leaning toward the EGR valve as well.

Those carbon monoxide and HC numbers are really, really good.

TRD95 · 10-19-2010, 04:51 PM

Quote:

Originally Posted by fenixus

yeah, unfortunately EGR valves tend to go bad over time as they get dirty with soot/carbon... and the way we all test them quickly (pull vacuum on running engine to see if it stalls) is a half ass test proving really nothing except the rubber diaphragm not leaking vacuum... still the valve can be very dirty at bottom causing it to either unable to fully close or get fully opened when needed.

I had to replace mine for the exact same reason even though it passed the mentioned testing.

Couldn't say it any better. But yes, those EGRs run stupid dirty after awhile...

Nervous · 10-19-2010, 05:03 PM

Nothing what can't be solved by carb cleaner + wire brush, thou.

J_Gee · 10-21-2010, 10:56 AM

Thanks for your replies. Passed the re-test today. Yippee! Had the EGR changed and the EGR Vacuum Modulator filter cleared. Also, don't know if the weather had anything to do with it. Was super hot during the original test, but nice and cool for the re-test. Thanks again everyone!

***fenixus*** · 10-21-2010, 11:25 AM

Quote:

Originally Posted by J_Gee

Thanks for your replies. Passed the re-test today. Yippee! Had the EGR changed and the EGR Vacuum Modulator filter cleared. Also, don't know if the weather had anything to do with it. Was super hot during the original test, but nice and cool for the re-test. Thanks again everyone!

congrats

enjoy your car now ... legally