emissions riddle

[jeff13]

Hey guys,

I have a friend who's 04 Maxima failed emissions. No CEL and its not burning gas efficiently (yeah, I know shocking). My s13 has a sr20det that passes emissions, so i've done the emissions dance a few times and not a complete idiot on getting it to pass.

here is the riddle:the guy who did the work told her it was something in the steering column that was causing a 'misfire'. . . . i'm not sure what that means. I assume its the ignition but how does that affect anything?

I told her to check all the usual suspects and that a failed O2 will cause a CEL. I'm thinking plugs, air filter, maybe fuel filter. what do you guys think?

thanks

[MaximA32]

That's interesting. I'm willing to bet NoX was too high as that's what causes most failures when there isn't a CEL or anything of the like. NoX being too high is generally caused by an issue with the EGR valve as the EGR system is designed to keep combustion chamber temps down. Another possible cause would be a lean condition. As far as the guy telling her it was something in the column causing a misfire, highly unlikely as the CEL would come on if there were such a condition. In regards to changing the plugs and what not, I would see how many miles there on the car before incurring that expense. I would check the air filter and check the throttle body to see how much carbon build up has occurred and get that cleaned up if it's too bad.

[loystock]

I agree that it's too early for such model year to fail smog check. This could be an indication of deferred maintenance. How many miles on the car ? Any recent maintenance history?

From your statement, looks like the car has been running rich (high level of HC) due to ignition problem. The OEM plugs are rated up to 105K miles but are typically replaced at 60/90K miles. So it's important to know car mileage. Check all ignition coil connectors. If possible, do a spark test. A fuel injector may also be failing. Also check for vacuum leak. And as Kenny mentioned, check/replace air filter and clean TB.

A fouled up/contaminated O2 sensor, may cause the ECM to give a rich or lean command depending on the location of contamination. If there is leak in the exhaust (cracked or leaky gasket), intake plenum tubes/hoses and even head gasket, the O2 sensor will detect a lean condition (more O2 in exhaust).

If the car has been running 'rich' for an extended period of time, the O2 sensors and catalytic converters may fail prematurely. There are 3 'cats' and OEM ones are very expensive. A defective/failing cat (damaged honeycomb) can no longer do its job of of oxidizing the HC and CO (in to H20 and CO2), nor reduce the NOx (into N and O2) of the combustion byproducts. So if the car is running rich there will be a high level of HC at the exhaust. If the car is running lean, NOx level will be high. Either one will fail emission test.

[MinisterofDOOM]

Get codes read anyway. CEL does not come on for all codes. If there is a misfire, it'll almost assuredly show a code that'll at least give some indication as to why. But if the car had a misfire issue, the car would most likely be running noticeably rough.

[nissangirl74]

Just gonna throw my .02 in here.

As far as the guy telling her it was something in the column causing a misfire, highly unlikely

I think the mechanic was wrong or had no idea and made something up. Tell your friend to get the car re-tested. Run the crap out of the car ahead of time, get it really hot, all the way up to operating temperature, run the A/C if you have to. Check for codes even though you aren't getting a CEL. Problems won't always throw a light. It it's the cats, they should be replaced for free under federal law (depending on mileage).

[jeff13]

Hey everyone, I really appreciate the comments and advice. I will find out the mileage and maintenance history but she takes care of the car pretty good.

I did not know there could be problems that don't cause the CEL to light up. I will check to see if there are codes. Really good to know about.

I didn't think it could be the cat since my SR is running stupid rich and it hasn't killed the cat in three years. . . but seriously, the Maxima has three cats???? How many O2 Sensors on this thing: 4 or 3?

I really had an issue with the steering column, misfire thing. I don't mess with any cars built this century so I had no idea what that was all about but it just sounded wrong.

Does anyone think the guy was referring to the OBD connector and just saying it has to be 'reset' or clear the code or something simple? For $200, thats the only thing I can think of . . .

[goody90q45]

Hey guys, I have a friend who's 04 Maxima failed emissions. No CEL and its not burning gas efficiently.

here is the riddle:the guy who did the work told her it was something in the steering column that was causing a 'misfire'. . . . i'm not sure what that means. I assume its the ignition but how does that affect anything?.....

There's quite a few codes that won't light up the CEL. Scan through the FSM starting at about page EC-50 to get an idea of the assortment of misfire codes available to you. I don't think any of them involve working on the steering column.

At this point the best thing to do is pull the codes yourself so you can go back to the shop knowing what needs repair. It looks pretty simple and can be done sitting in the front seat with no special tools, just count the number of times the light blinks. Self-diagnosis starts on page EC-68.

http://www.nicoclub.com/FSM/maxima/2004/

[loystock]

1999-CA configuration and all 2000 and beyond Maximas and have 3 'cats' (Bank 1 Pre-Cat, Bank-2 Pre-Cat and main Cat) and 4 O2 sensors (2 for each Bank 1/2 Pre-Cat. There is no O2 sensor downstream of the main cat, unlike in the earlier Maximas. The older Maximas have 3 O2 sensors

It would be better to have the printout of the failed emission test so we know where it failed. And as Becky pointed out, the car could have been 'cold' when it was tested and 'prepping' the car prior to test may allow it to pass. And as always, better get a scan for possibility of 'ghost codes'.