Runnin' Rich

[NISMO240SXSE1]

My 89 240sx sohc won't pass smog because my fuel mixture is too rich.Any help would be appreciated

HC ppm:42
CO%:1.2
CO2%:14.4
NO ppm:52
O2%:0.0
mph:24.2
Load ft-lb:80.9
HP:14.6
Acc MPH/s:0.4
RPM:2845
This is just one of many lines on the printout they gave me.I took my car to MOSSY NISSAN in San Diego and after changing the maf sensor ground wire they said"we can't find anything wrong with your car".They blamed everything on my aftermarket parts(intake,exhaust,ignition...)but when I put the stock airbox back in and removed my MSD the readings were worse!If anyone has any advice please help!
Thanks!!!!
Ed

[Ritz S14]

Check your Oxygen sensor.. It's only a one wire..they run about $20 wholesale, and is a piece of cake to change.

[DJ_Sunrise]

dont forget the coolant temp sensor, ur car runs rich in the begining to warm up the cat, aka.. reduce emissions. if ur sensors shot, the car will constantly run rich. replace both 02 sensor and ECT sensor, good luck.


~Sunrise

[Demik]

just get a SR Ed .............

[NISMO240SXSE1]

Thanks.....hey, why don't you hook me up with an SR,Chris.

[idlafie]

Originally Posted by NISMO240SXSE1

My 89 240sx sohc won't pass smog because my fuel mixture is too rich.Any help would be appreciated

HC ppm:42
CO%:1.2
CO2%:14.4
NO ppm:52
O2%:0.0
mph:24.2
Load ft-lb:80.9
HP:14.6
Acc MPH/s:0.4
RPM:2845
This is just one of many lines on the printout they gave me.I took my car to MOSSY NISSAN in San Diego and after changing the maf sensor ground wire they said"we can't find anything wrong with your car".They blamed everything on my aftermarket parts(intake,exhaust,ignition...)but when I put the stock airbox back in and removed my MSD the readings were worse!If anyone has any advice please help!
Thanks!!!!
Ed

For a glossary definition of Smog terms, click on the attached link:
http://www.smogcheck.ca.gov/StdPage....y-May_1996.htm
It's pretty good at helping you troubleshoot WHY you failed smog as it explains each field. The Primary field/definitions you need to be concerned with are HC - Hydrocarbons, CO - Carbon Monoxide & NO - Nitrogen Oxide.

In order to pass your smog test, you may want to do the following:

If you haven't already done so, change both your air filter & fuel filter. Also, check & clean the following:

check all your vacuum lines to see if any are leaking or are not connected. Start the car up & listen for a hissing sound, (kinda like a snake...ssssss).
1). Pour a can of fuel injector/valve cleaner into the gas tank. Helps to remove carbon buildup on valves and insure a better spray pattern thru the injectors.
2). Spray carburator cleaner into the throttle body - also helps to remove carbon buildup in the intake manifold.
3). Tuneup - change the distributor cap & rotor along with the spark plugs to guarantee a good clean spark in the combustion chamber.
4). You'll need a timing light for this step. Check your timing with a timing light 89-90's should be at 15 degrees - 91(??)-98's should be at 20 degrees
5). You'll need a tachometer for this step. With the engine already warm, readjust your idle to 700 rpm (+/- 50 rpm) - this is done by disconnecting the three wire throttle position sensor harness located directly above & to the front of the throttle body intake. Once the throttle position sensor harness is disconnected, then you should be able to set the idle with the idle speed adjusting screw located on the passenger side of the engine towards the rear of the intake manifold.

Regarding #5, from my experience on working on other people's 240's, I've noticed that the idle is usually set lower than it should be. Here in California, because of biannual smog checks most smog check technicians will lower the idle to get cars to pass the smog test. If your state has annual/bi-annual smog checks, you may want to keep in mind that the idle may have been lowered by a smog check technician causing your low idle problems.


6). Clean and re-grease (with dielectric grease) the following two connectors/harnesses. 1). Engine Coolant Temperature Sensor & 2). Mass Air Flow Sensor. A faulty signal from these two wiring harness/sensors will cause your idle to fluctuate.
7). Make sure your EGR valve is working properly. Place your finger underneath the EGR valve with one hand & with the other hand rev your engine for a few seconds. You should feel the float on the bottom portion of the EGR raise up slightly. It means your EGR is working fine.

You might want to see if your ECU is throwing any codes:
Go to www.240SX.org and click on the FAQ link. When the FAQ page opens, scroll down the links on the left side till you get to ECU-Reading Trouble Codes DOHC. Click on that link & follow the instructions. While you have the ECU in diagnostic mode, you might also want to check the Oxygen Sensor to see if it's working properly also. The www.240sx.org FAQ page will also have instructions on how to check it.

Anyhow, I hope the above helps...

ID

PS: If this e-mail seems like it's been cut & paste, that's because it has! I pulled old posts & modified them to answer your post. Anyhow, I hope the info helps

EDIT: 06/18/08
The California Air Resources Board went & changed their website....:Listed below is the CORRECT link...

http://www.bar.ca.gov/80_BARResource..._Glossary.html

[NISMO240SXSE1]

Hey,thanks for the help i'm gonna try evrything tonight and tomorrow so hopefully I get it to pass!!