failing smog check

Reply

  #1  
Old 04-26-04, 01:47 PM
borg71
Visiting Guest
Posts: n/a
failing smog check

My 92 Accord LX (odometer = 216K miles) failed CA smog test this year for the first time. I did drive around for about 10-15 minutes on freeway and left the car idling until the tech took it in to test. The emission test shows:

At 15mph, 1834rpm
%CO2 = 14.8
%O2 = 0.1

HC Max = 116 ppm
HC Avg = 31 ppm
HC Meas = 102 ppm

CO Max = 0.74%
CO Avg = 0.10%
CO Meas = 0.78% <-- fail

NO Max = 791 ppm
NO Avg = 237 ppm
No Meas = 492 ppm

At 25mph, 2002 rpm
%CO2 = 15.0
%O2 = 0.1

HC Max = 91 ppm
HC Avg = 20 ppm
HC Meas = 86 ppm

CO Max = 0.62%
CO Avg = 0.09%
CO Meas = 0.53%

NO Max = 730 ppm
NO Avg = 199 ppm
No Meas = 547 ppm


Search on previous threads in this forum and the web seems to indicate that I should do a tune up including replacing air filter, spark plugs & wires set, distributor cap & rotor, O2 sensor, oil & filter. Also the fuel injectors may need to be cleaned.

The spark plugs, air filter, oil & filter were all replaced relatively recently already (prior to smog check) and the car has hardly been used since (probably the same tank of gas in there for a few months already). O2 sensor, cap & rotor are probably original one that came with the car. Can't remember when the plug wires were changed and also I was told that a valve adjustment is due.

Since I have a spare new air filter, I swapped it in anyways. And I am planning to do the plug wires, cap & rotor, O2 sensor, and valve adjustment.

My questions are:
1. Am I missing anything else that I should do before getting another smog check?
2. The quote for O2 sensor from Honda dealer is $220. But ones from parts stores like AutoZone & Kragen cost $87 (for Bosch) to $242 (for Borg Warner). The price difference seems too much. Can those cheap sensors be trusted? Does anyone know the OEM for the original Honda sensor by any chance?
3. Do I still need to change oil and filter as the oil in there looks like I have practically just changed it?
4. Would the old tank of gas played a factor? Should I use those fuel system cleaner and get a new tank of gas too?
 
Sponsored Links
  #2  
Old 04-26-04, 02:56 PM
Member
Join Date: Apr 2002
Location: Pittsburgh,Pa
Posts: 2,417
Plug wires,cap,rotor and valve adjustment won't help but with your mileage it sure wouldn't hurt.I would change the O2 sensor and the oil again it will most likely pass since you only failed by .04 CO.The thing is the catalytic converter is probably getting tired at that mileage and a new one will make it pass without any other repairs.However changing the other parts will make the cat last quite a lot longer.
 
  #3  
Old 04-26-04, 03:04 PM
Desi501's Avatar
Member
Join Date: Oct 2003
Location: Boynton Beach Florida
Posts: 2,207
I don't think the ignition system is hurting you at all with the low HC readings. The high readings are in CO which indicated a very rich mixture but the low HC indicate the ignition is burning it completely. You need to look at things that effect the mixture like O/2 sensor, map sensor and it's vacuum supply, air filter, fuel pressure, temp sensors, both coolant and intake air. Those are a good places to start but there can be many more possibilities.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Davo was posting at the same time as me. Is that right, it only missed by .04 CO with a reading of .780? I expected that need to get much lower.
 
  #4  
Old 04-26-04, 05:18 PM
Member
Join Date: Feb 2004
Location: So Cal
Posts: 248
Originally Posted by borg71

My questions are:
1. Am I missing anything else that I should do before getting another smog check?
2. The quote for O2 sensor from Honda dealer is $220. But ones from parts stores like AutoZone & Kragen cost $87 (for Bosch) to $242 (for Borg Warner). The price difference seems too much. Can those cheap sensors be trusted? Does anyone know the OEM for the original Honda sensor by any chance?
3. Do I still need to change oil and filter as the oil in there looks like I have practically just changed it?
4. Would the old tank of gas played a factor? Should I use those fuel system cleaner and get a new tank of gas too?
1. Make sure the timing is "spot on". Overadvanced timing will cause elevated HC & NOx.
2. The Bosch O2 sensors will work just fine. Just make sure they have a "plug 'n play" connector. Forget about crimp connectors. Solder and shrink tube is OK if you have to.
3. Fresh oil NEVER hurts!
4. Fresh gas is good. Go with 92 octane because it burns cooler and will keep the NOx down.

If you need any more help, just holler.

Matt
 
  #5  
Old 04-26-04, 06:17 PM
borg71
Visiting Guest
Posts: n/a
Desi,

Yes it failed by only 0.04. It was so close the tech voluntarily used a big fan on the car and reran the test.

Maybe I am not understanding it correctly.. but I thought the process is HC + O2 -> CO2 + H2O if enough O2 is present. If there isn't enough O2, then you get only partial conversion hence low HC, low O2, but high CO? Hence need to check on air input?

But I'll check the other sensors you mentioned since personal elbow grease is free..



Smogtech,

Emissoin test result sheet indicates 15 BTDC. Factory manual says 15 +- 2 BTDC so I think I am ok there.

As for Bosch sensor, I guess I am a little bit worried about the Bosch name especially when it's so much cheaper as I paid extra for some Bosch platinum plugs before on this car and they worked like crap and had to switch them out with the OEM NGK regulars.
 
  #6  
Old 04-26-04, 06:38 PM
Member
Join Date: Feb 2004
Location: So Cal
Posts: 248
Well, I agree about the Bosch plugs, but the O2 will be just fine. I just put 2 of them from AZ in my '88 Accord and according to my DSO they're switching just fine. It's up to you though, it is your car.

Whenever I put plugs in a car they get OEM. AC for GM, Motorcraft for Ford, etc.
 
  #7  
Old 04-27-04, 05:20 PM
Desi501's Avatar
Member
Join Date: Oct 2003
Location: Boynton Beach Florida
Posts: 2,207
Originally Posted by borg71
Desi,.

Maybe I am not understanding it correctly.. but I thought the process is HC + O2 -> CO2 + H2O if enough O2 is present. If there isn't enough O2, then you get only partial conversion hence low HC, low O2, but high CO? Hence need to check on air input
.
The easiest way to explain it is that HC is "unburned" fuel caused by incomplete combustion like a misfire condition. CO is "burned" fuel and means the ignition did it's job but there is just too much fuel.
 
Reply


Thread Tools
Search this Thread
Display Modes
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 11:32 AM.