1993 240sx failed smog, high CO and HC, NO is ok

[NotDave]

tune up was done a month ago. replaced:caprotorspark plugs (gapped appropiately)spark plug wiresfuel filterair filter was still good

fuel pump was replaced two months ago. just throwing this out there incase it might have something to do with it

car was warmed properly, premium chevron 91 gas was usedtiming was checked afterwards. technician said timing wont give me readings as bad as i got mine.

help me im poor



Modified by NotDave at 4:24 PM 1/31/2006

Modified by NotDave at 4:26 PM 1/31/2006
Modified by NotDave at 4:29 PM 1/31/2006

[Silvia2NR]

oxygen sensor

[Ni2s4s0aSnX]

It says right on there that it is the ignition timing. Open your eyes and do some work for your self for once. I'm tired of people with these question coming on here. People asking questions like why is the low fuel light on and why is the fuel gauge say empty. Maybe its because you need gas jackass. Sorry.

[navysnail]

maby i am missing somthing but i do not see anything on there that says his ignition timing is off. it shows as 25 degress BTDC (should be around 20)

what I do see that failed is the fuel cap. that needs to be replaced (should only cost a few dollars) ad make sure you have your car in the best running condition when you take the test. warm up the engine by driving at least 12miles, new O2 sensor, check your CTS and MAF (a search on this site will bring it up)

[rsmithdrift]

results are on the left of the item it is describing. Fuel cap passed, timing failed.

Also, get an O2 sensor for god sake. It's 17 bucks for a bosch and it's a 15 minute install. They are supposed to be replaced every 60k or so and I'm sure it's never been done on your car if you never done it. If nothing else it'll get your MPG WAYYYYYYYYY up because I can tell by your CO reading that you're running EXTREMELY RITCH right now and that O2 sensor is 90% of the reason. Timing will help, but not that much.

My car had the exact same readings as your (timing at 20* though) and all I did was replace that sensor and then it passed with 0% CO and 15 ppm HC.

[hazw8st]

It says right on there that it is the ignition timing. Open your eyes and do some work for your self for once. I'm tired of people with these question coming on here. People asking questions like why is the low fuel light on and why is the fuel gauge say empty. Maybe its because you need gas jackass. Sorry.

You're right on! If the car is relatively stock, you should pass with flying colors. Adjust the ignition timing, and you'll pass.

[NotDave]

replaced O2 sensor and coolant temp sensor. set timing at 20. did a pretest and got the same result

possible air flow meter?

[hazw8st]

replaced O2 sensor and coolant temp sensor. set timing at 20. did a pretest and got the same result

possible air flow meter?

[

Hook the vehicle up to a OBD scanner, turn it on and look for codes. if some codes pop up, diagnose the code, then fix the problem. Also, make sure that the person who did the last tune-up hooked everything back up how it supposed to go. If you vehicle is relatively stock and in good condition, the car should pass.

[180fan]

First off, you need to fix your fuel cap.

Have you checked the MAFS and the CTS?

[NotDave]

gonna go test the MAF today. CTS was already replaced

for the MAF:Key on engine off should be 0.2volts at idle should be 1.0-1.4

right?

[hazw8st]

gonna go test the MAF today. CTS was already replaced

for the MAF:Key on engine off should be 0.2volts at idle should be 1.0-1.4

right?

gonna go test the MAF today. CTS was already replaced

for the MAF:Key on engine off should be 0.2volts at idle should be 1.0-1.4

right?

Also, if the MAF checks in good, try cleaning the MAF element with some non-flammable electronic parts cleaner. That usually cleans it the first time.

[InsanityInc]

It says right on there that it is the ignition timing. Open your eyes and do some work for your self for once. I'm tired of people with these question coming on here. People asking questions like why is the low fuel light on and why is the fuel gauge say empty. Maybe its because you need gas jackass. Sorry.

You know, you ought to try knowing something about cars before you try to act like a know-it-all. The only problem advanced ignition timing will give you is high NOx readings, and possibly high HC if it's REALLY advanced and your engine is misfiring and detonating, but you'd have to be probably at around 35BTDC to get that to happen.

Most of this thread is idle speculation, but here's what your problem is:

Your CO is high, that means you are running rich, end of story. That's what high CO% means. I'd make a pretty strong guess that your high HC is also due to the rich condition. The most likely culprit is your throttle position sensor. Mine was off by .2v and it made the car fail smog with about 3%CO. Once adjusted, it had about .2% CO.

[InsanityInc]

Oh, and seriously, don't even bother getting it tested after you just fix your timing. Timing will never make your CO read high. Ever.

[NotDave]

Most of this thread is idle speculation, but here's what your problem is:

Your CO is high, that means you are running rich, end of story. That's what high CO% means. I'd make a pretty strong guess that your high HC is also due to the rich condition. The most likely culprit is your throttle position sensor. Mine was off by .2v and it made the car fail smog with about 3%CO. Once adjusted, it had about .2% CO.

good advice...ill check that out. i didnt have time to do the maf btw :o

[hazw8st]

It says right on there that it is the ignition timing. Open your eyes and do some work for your self for once. I'm tired of people with these question coming on here. People asking questions like why is the low fuel light on and why is the fuel gauge say empty. Maybe its because you need gas jackass.

You know, you ought to try knowing something about cars before you try to act like a know-it-all.

You're right on InsanityInc!

These forums are public avenues of information. We all learn by asking and learning from others. It's interesting that we all voluntarily log onto different forums and then proceed to bash and ridicule other members into submission that were only asking for our help in the first place. That is something to think about.

[NotDave]

ok i give up. i applied for the CAP program and now i took the car to a gold shield station to get it fixed. cost me 100 for the deductable and 10 for the certificate...they are still working on it now

[hazw8st]

Fantastic. Hope everything works out for you!

[NotDave]

they replaced what i was told to be a secondary egr valve thingy. not the egr but the 2nd piece to it. ~100 for the part. and they replaced a pcv hose that connects from the valve cover to the intake. and finally my gas cap (which is bogus btw since i the cap was tested and passed with the first smog inspeciton). the car barely passed smog but it did so im happy.

i have a strong feeling that they somehow scammed the smog since my car is OBDI and its easy cheat the smog machine. but i dunno im happy

[hazw8st]

Thats great Dave!