California SMOG Help Needed - High NOX at 15mph

[georgeecfc]

Hi 4runners,

Need your help on passing my Smog...

Facts:

-1997 4Runner SRS Limited 4WD - Stock with 175k miles
-Engine was rebuit about 5k miles ago after radiator broke and it over heated.
- Since then check engine light was on for piston misfire but since was running fine and seemed like an issue with the sensor when they put it back together I was fine with it.... Until I took it for smog and it failed due to the engine not being in a ready state (the check engine light).
- It did pass the emissions part though with the below readings
15mph
RPM:1636
%CO2: 15
%O2: 0.1
HC: 35
CO%: 0.18
NO: 406

25mph
RPM:1585
%CO2: 15.2
%O2: 0.0
HC: 21
CO%: 0.06
NO: 183

- I took it back to the garage who did the engine rebuild and they fixed the check engine (it was 3 pistons reading as misfiring) by replacing the sensors and some other related parts.

- I drove it a couple of hundred miles to get the engine ready for the smog and then retested... This time it passed the Functional check but failed on the emissions.

15mph
RPM:1624
%CO2: 15.3
%O2: 0.2
HC: 15
CO%: 0.01
NO: 1276 - pass level 512 max

25mph
RPM:1615
%CO2: 15.2
%O2: 0.1
HC: 10
CO%: 0.01
NO: 324

The only difference between the operating conditions of the first and 2nd test was the first one I drove for 15 mins on the freeway immediately prior to the test for the 2nd there was a line so the truck was sat for over an hour cold before the test.

Do I need to fix anything before I do the retest or just make sure the engine is at operating temperature?

Thanks again!
George

 

[phattyduck]

for the 2nd there was a line so the truck was sat for over an hour cold before the test.

Do I need to fix anything before I do the retest or just make sure the engine is at operating temperature?

Thanks again!
George

You should never shut off the engine while waiting for a smog check. Cold cats = poor performance. Ideally, you should take it for a drive, then pull into the test bay immediately. That's probably all you need to do.

-Charlie