94 q wont pass smog

[3Q Jay]

agree your NOx is way high. fix this first. must get the pipe rootered out, the egr valve itself clean, and then the elbow in the plenum clean. all been documented here many times before.

the reason your NOx got worse after ks replacement is that now the engine is seeing proper (assuming all else is good) timing advance. timing advance while good for power also directly affects and worsens NOx.have you checked your timing with a light? your base timing could be too far advanced also. retarding timing (within limits) will also help high HC numbers as the fuel has longer to burn out of the crevices especially near the ring lands.

you didn't post your CO, but i'm guessing those were borderline fail also. should be <0.05%.

[kevinpaigeking]

thanks for taking the time. i had already cleaned the egr thoroughly with brake disc cleaner. how do i go about rootering the pipe? ( i assume that is the pipe that leaves the egr) i have not replaced any O2 sensors since i bought the car. the muffler guy replaced one catalytic about 3 years ago, but inspected them recently and said they seem fine. He said to have codes read before any action. I just spent more money than I intended to clear the engine light so I could pass smog, and now it's as if I am starting all over. Not to mention this ticking sound that is present since the repair. Will paying to have codes read insure the most direct solution to these high emmission numbers

[jimbyjimb]

No need to pay on a Q. Nissan is kind enough to make their ECU's available with self-diagnostics. Consult Q45.org for info on ECU removal and code reading. It is VERY simple, any monkey can do it. You can also erase codes as well.

[3Q Jay]

good start if the passages in egr body are good, but the pipe down to the exhaust mani must be cleared and the plenum elbow. i used a really long flexible bottle brush (like a test tube brush, but 24" long). i think it came from justman brush or something like that.

the good news is you can do this whole egr cleaning for about $15 in parts/tool/solvents (be sure to replace the egr to plenum hi temp gasket) and some elbow grease.

agree on the free codes. dont turn the screw too hard.

[maxnix]

And don't believe in after market catalytic converters. They contain far less precious metal and hence live much shorter lives. Are you certain the old one was indeed bad? Very very seldom do they fail without owners intentional neglect.

[kevinpaigeking]

i went to q45.org and did not see instructions on how to pull codes. can you give me a direct link

[kevinpaigeking]

never considered aftermarket catalytic. only asked about O2 sensor replacement from aftermarket

[maxnix]

never considered aftermarket catalytic. only asked about O2 sensor replacement from aftermarket

Pretty much the same story. Only NTK and OEM.

You have to dismount the ECU and read the flashes for the stored code. Long for tens, short for units. Much easier to use laptop and cable. See the Blatz and other thread from slipnfall.

[Rex]

i went to q45.org and did not see instructions on how to pull codes. can you give me a direct link

http://www.nicoclub.com/articles.php?id=60332