I have a 1999 Nissan Maxima SE with 32K miles and I took it for emissions and I failed! I live in Northern Virginia. The car has Stillen intake, downpipe, and catback exhaust.
It failed the 25 mph test where the Hydrocarbon level was 115 while the limit is 78. It passed the other tests.
Anyone have any ideas? Maybe its a misfiring plug or wires? The car was warmed up before it was taken for the test.
thanks in advance
KRIS

 

not just warm...

I think hi HC readings are when you get a lot of unburned gas... such as when the engine is running rich during warmup or not just at proper operating temps (ie fully warmed up)... That was the job of the precats...

 

Please corect me if I am wrong. I am sure I read in a previous post that running low octane gas and having a HOT engine will do it. Hope this helps. Good luck

 

The engine wasnt hot since i drove the car for around 10 minutes. So do you think I should drive the car real hard and then take it again. It should then pass, dont you think?
Would I have to put back the old exhaust or look for arcing or a bad plug?
Thanks

 

The problem is not spark plug wires. 4Gen Maximas don't have spark plug wires.

The problem is not likely to be a misfiring plug. A misfire turns on the Malfunction Indicator Light (a/k/a Check Engine Light, Service Engine Soon light) and stores a Diagnostic Trouble Code to identify the misfiring cylinder.

 

Always do you smog test after running the engine normal temps such as after some highway driving... It should improve the test results... I believe quite a few people here have passed the sniffer portion of the inspection with your setup...

 

Try run high octane gas and buy some those NOS octane booster. I'm running CAI, Stilen Y, no cat and Stillen cat back. I'm in Northen VA too. I'm not even going to bother with inspection and emission after hearing your experience. I was going to put my stock cat back on and give it a shot. Now, I'm just going through the under the table method.

[Edited by 1MAX2NV on 03-03-2001 at 09:02 PM]

 

ox sensors maybe.

 

Where in Northern VA do you live ? I still have the main cat and that part passed emissions. What I will do is run the car at highway speeds and then take it again. If it fails again, then I will put the entire stock exhaust system back.
Thanks
KRIS

 

Daniel,
I just realized today that the car doesnt have spark plug wires. So if its not that or a misfiring plug, do you think it could be the the Y pipe that replaced the stock cats?
I still have the original exhaust system so I might end up replacing it back to original.
Any other suggestions?
Thanks
KRIS

 

There are those that have passed by adding a Random Tech high-flow cat. According to their site they do better cleaning than stock cats.

 

My own Maxima is "bone stock" and I have scant knowledge of mods such as your Y-pipe. Certainly, that mod could affect your emissions test results. However, other engine problems could cause this problem, even on a stock engine. Anything which causes an over-rich mixture is a possibility.

- sticking fuel injectors
- bad fuel pressure regulator
- obstructed fuel return line
- "tired" oxygen sensors
- bad Engine Coolant Temperature Sensor
- anything which prevents the Engine Control Module from going into Closed Loop Mode
(such as a stuck-open thermostat)

 

Daniel has listed many possible causes of a rich mixture.

But since your car is a 99... it would seem a little unlikely for many of them to go bad so soon. Are you getting horrible gas mileage?

Did they have a recall of O2 sensors for the 99?

I still think it might be the luke warm engine....

 

the guys are right. Many people i know here in nyc, drive their cars around for a bit. highway driving like 25-40 minutes and you should be ok. The engine wasn't at running temp, that is why you failed the test, better luck next time

 

Chunger,
I am getting great gas mileage and I only run premium gas.
I am getting 23 city and 30 hwy since I have a stick.
Well I will drive it for a long time , maybe half hour and then take it in. I hope it passes and if not, I will put the original exhaust system back.
Thanks for the tips
KRIS

 

Dang...i'm jealous... i haven't see mileage figures like that for a long time... I think I have to replace my O2s soon...

I really think you'll be fine with the engine hot...
Let us know what happens...

 

Since I am pretty upset about this, I am going to put everything back to stock save the intake and then make sure it passes. I will try it one more time after the engine gets hot.

 

ive seen people post their results before, but if youve just recently gone, can you post your results? i want to see how much the y pipe affects levels.
thanks

 

I just had emissions done on my car('97), im out in Utah and not sure if our levels are the same as yours because I didnt get a breakdown of how my car did, all I know is that it passed. Im running pretty much all the exhaust goodies including the random tech cat AND I drove my car for about 20 min at highway speeds before I brought it in.

 

I just had my emissions checked on Monday, in CT. I was comparing the results to my last inspection, which was in 2000. Here are the results. The allowable limits are in parenthesis:

2002
HC: 6.5 (78)
CO: 0 (.43)
NO: 418 (585)

2000
HC: 7.9 (76)
CO: 0 (.42)
NO: 2 (566)

I always drive the car 20-30 minutes (including on the highway) before the test. However, this latest test shows my levels of NO getting close to the limit. Any ideas? (btw, CT always does the 25 mph dyno test to get their results)

Eric

 

I recently passed my NYS inspection with a recently added Y pipe. My HC and CO levels went up and my NO actually went down, Odd. Also, my HC levels got very close to the limit.

Check the thread here;

Passed NYS Inspection