Soooo last year I failed emissions and this year I failed emissions. Here is a scan of the print out I got back. I'm not sure what to target. I read high NOx can be the EGR failing but would it be that high?



Here is the issues thread I had recently.

http://forums.maxima.org/3rd-generat...ng-update.html

I've been driving trouble free since then. However here are a few things that may affect the emissions maybe?

- timing is slightly advanced...my friend marked the original spot but maybe the car still was advanced before because the NOx last year was in the 1500s...
- TPS still needs to be calibrated
- non-OEM high flow magnaflow catalytic converter...I'd gather I need a normal one if I want to pass don't I?

Take 2 - 1 gallon ethanol, 4 gallon premium, timing at ~15 degrees, new air filter, cleaned EGR, checked all vacuum lines (no leaks per starter fluid sprays)

Result: FAILURE

Take 3 - timing retarded to 10 degrees, new catalytic converter from rock auto, full tank premium gas

Result: FAILURE

Oh yeah so it sucks...butt dyno says the new cat feels slower

 

high NOx means high combustion chamber temps.
the car may be running lean, retard the timing a bit and toss in a bottle of rubbing alcohol before the next test.

 

Yeah I totally forgot to retard the timing. I hopefully don't over do it. There's the original x made where the timing was supposed to be. Should I retard it past that?

Speaking of which in reference to my other thread. I had changed the spark plugs back in 4/2008 but should I have to change them after having all those issues? I'll pull them tomorrow to check and make sure they're looking okay.

 

Would all that clear out the high HC at low RPM?

 

wow dude ur NOx are flying....it happens wen combustion temp reaches over 2300F....check to see if ur engine isnt over heating plus i m not sure about the high flow cat cuz i never used it but it could be the reason that ur NOx getting over 3k...and looks like u r running extremely Lean which is making the NOx go up....u could run lean if u have a bad fuel filter or dirty or havnt changed since Alexander times... u could run lean cuz u have a bad fuel pump...u get the point right? fuel isnt getting where it suppose to be at the right time with the right pressure. and please do retard the timing i would say retard it a lil bit further from OEM but not much....retarding will bring NOx down and take the other 2 up but dont worry NO x will come down much faster than others

 

Well if you followed the previous thread I had, the fuel filter was one of the things I changed. Not sure how to check the fuel pump though. I'm not sure how off the timing is without checking it with a gun but I do have the original point...its advanced by about 1 or 2 mm off the mark. I'll check it later today.

My temperature gauge doesn't actually work. It'll go to half way sometimes and then bounce up high and then go back to zero...so I don't know if the sender unit or the gauge is broken.

 

Hidden turbo?

 

Look for a vacuum leak or a non-functioning EGR. Thsoe are the most common causes for a high NOx value.

Missing vacuum hoses, failed intake manifold gasket or injector o-rings, dead EGR, etc.

to find a vacuum leak, go get yourself a can of starter fluid, start the car, and then hose down all of the lines on and around the intake manifold, as well as the mating surfaces of the manifold to look for a failed gasket.
spray.. wait a sec.. spray.. wait a sec.. spray.. etc.. etc etc..
if you find the leak with the spray, you'll hear the idle jump around pretty obviously. voila.

 

+1^ and check your PCV valve and change your oil and filter....Be sure to warm up the car b4 testing

 

I changed the oil about 250 miles ago? Should I do it again? And I believe the PCV valve was changed maybe 275 miles ago over the summer.

I forgot to mention the last time the car was driven extensively was back in Summer '08. Then the bucking / hesitation happened so it was parked for a long time.

So here are things I've done already. Drained the gas tank, new fuel lines, new fuel filter, pcv, fluids, water pump / coolant overhaul, new cone filter...

I also changed the spark plugs to nissan NGKs back in april '08 and that was about 1250 miles ago. Not sure if I should change them? I pulled them today...I'll post pics in a bit.

I'm not sure if anything else is left out. I bought some carb cleaner for the EGR cleaning and starter fluid to diagnose for vacuum leaks but I remember all the vacuum lines were changed to account for the hesitation issue. I also got some seafoam so maybe that'll clear out some stuff. Last resort will be a bottle of denatured alcohol from the paint store for the gas tank.

 

Are you burning any oil? What kinda condition is your regulator bypass in? Mine was corroded and I found a brand new one in the junkyard...Are you sure that your air/vacuum lines are connected properly? It's something simple....I've got my DD 86.5 Nissan HB pickup with Cam, headers, hi flow cat, 2.25" catback, Twin MSD oil filled coils, running 15 degrees ignition timing and 3 degrees advanced cam timing,....and I passed emissions with flying colors! Check all your pneumatic items for proper ops and maybe see if you can find some E3 spark plugs to burn more during the ignition process.....

 

Did the free retest today and...still failed.



I checked for vacuum leaks with starter fluid and I didn't notice any rise in the rpms. We reset the timing back to 15 degrees. The vacuum lines look like they should be correct. We compared it with another 5 spd ve30de manual. My friend's passed and mine didn't. Unfortunately this emissions test was actually with 1 gallon of denatured alcohol with about 6.5 gallons of premium. Maybe it was diluted too much but I'll have to pay for the next emissions test. Time to go to one of the ghetto places.

On another note. I'm not sure what condition the regulator bypass is in. I actually don't know what part you're refering to...

 

I PM'd you

 

Here TV4184, this cardomain site helped me route and double check my vacuum hoses....Plus there is an awful amount of good info regard the emission side of this vehicle and performance related info please read "It's your only hope"......I used alot of this info to gain as much power as possible to my discretion....
http://www.cardomain.com/ride/748507 This guy is deeply into his hobby....I can respect his knowledge....

 

3rd take...failed again. New catalytic converter...may not be fully activated yet but would it still be that high? That's after driving around for an hour.

And I found emissions read out from May 2006 before the car was left in the driveway unused for 2 years until I bought it in April 2008. The read out shows ALL levels are almost zero. It's even better than the car the inspection shop used to get me a sticker for this year. I really want to know why all of a sudden the NOX would be going through the roof if nothing was changed from May 06 to April 08. It failed then as well as now. Any ideas aside from what I've listed so far. I can recount all that has gone on with the car if necessary.

 

Seems that you may have a vacuum leak. Start checking the hoses that control the EGR, power valve, water **** valve, carbon canister, etc. Although you mentioned that you have checked them with starter fluid, that may not have been enough. Probably it would be best to start replacing them all if you have not done so.

Also, high NOx can be caused by high engine temperature. So check if the fans and the engine coolant temp sensor are working properly. If you have not done so, changing the coolant may help as well.

EDIT: I read your previous thread and it seems that you covered the vacuum hoses and the ECTS was replaced. I guess check the fans and make sure they are running.

 

All good checks. Thanks for the help though. I did have to rebuild the CTS harness too. My temp gauge acts up sometimes it goes to over heat, sometimes it goes to 0 and to the middle...I need to find a new one. The other thing someone said was to change the thermostat? That it may be stuck partially open?