KA24DE Emissions fail

[kibblez]

91 240sx S13 [ka24de] 3 in. exhaust

Noob needs help,I have searched for similar threads but didnt come up with too many results so i appologize for reposting if this has been said before. If you stick through the whole thing i appreciate your time and any advice is greatly appreciated as i have just failed my 6th emissions testing.

Arizona emissions, testing HC, CO, and NOX levels.

first test, passed HC and NOX just barely and failed CO pretty bad.

Checked injectors, O rings were getting pretty torn up so replaced rings, replaced plugs after being dumped with fuel, check timing, no evidence of anything else being suspect.

second test, failed all three with flying colors. HC, CO, NOX all sky high.

Checked injectors, still having torn up O rings, replaced rings again with O Rings from Home Depot, changed plugs again, timing, checked dizzy, wires, fuses, everything seems good.

tests three - four, did checks on everything, i cant remember everything i did but i gained confidence again and retested. fail.

Ran Seafoam through, smoked out the neighborhood, ran HEET, fuel injector cleaner, heet and seafoam through the gas tank, changed oil, plugs good, wires good, re-taped wiring, no evidence of vacuum leaks, nothing disconnected, EGR service test was good, did timing, MAF good, replaced air filter, faked the AIV, mixed 91% rubbing alcohol with 91 octane gas 1/4 tank and pulled an injector, time for retest #5.

Passed HC and NOX and still failed CO barely.

checked plugs, evidence of running lean. Ran self diagnostic, giving code 34, repaired knock sensor, gave me code 55, all is good in 240 land. Timing seemed to have adjusted itself to normal. last minute inspection on everything, yayyy, retest.

sixth test, awww failed all three. Epic Failure.

Anyone have any ideas? Any advice is greatly appreciated. Thanks again.

[faeasjepardo]

I am by no means an expert , i know very little about cars, my 240sx is my first car. But when i got my inspection done i failed my emissions twice, third was a charm.I ran Seafoam, oil change, replaced the EGR valve ( which i think was the main culprit as my NOx was high), then just for good measure i got a $10 O2 sensor from Autozone, I don't know if you changed this or not but it maybe worth a try. My KA has 212k on it,just to give you an idea of what an old girl she is :pGood Luck.

[nifares240]

did you run the car with a fan blowing the motor? if not, this causes the car to heat and work harder. running with a fan simulates highway speeds and tends to cool the motor.

my twin cam passes emission with header, test pipe, full exhaust, and disconnected EGR.

[carmo]

There's no way you passed an emission test with all of your emission controlling devices disabled. Either New York is really slack or you knew the guy. Or they held you to 64 Impala standards. Anyway, HC (hydrocarbons) is raw gas, NOX (oxides of nitrogen) is caused by excessive combustion temps, and CO (carbon monoxide) is caused by excessive rich mixture. To solve your problem, it may help if you first understood the theory. This web page should give you some insight as to how to make sad days in 240 land happy once again. few things to remember1. Catalytic converters store oxygen to be released in the presence of excessive carbon monoxide. Oxygen mixes with CO to make CO2.2. EGR displaces about 10% of of your combustion chamber volume with an inert gas (exhaust fumes) thus cooling combustion temps which reduces NOX.3. Front 02 sensors directly effect air fuel mixture by relaying exhaust info to ECM.4. Rear 02 sensors are purely for detecting a catalytic converter failure. The ECM will see both 02 sensors mirror each other thus indicating no oxygen store and release. The rear 02 should almost flat line while the front will show almost a sign wave pattern, indicating rich, lean, rich, lean, rich, lean etc.5. coolant temp. sensors that tell the ECM it is colder than it really is will cause the car to run rich.6. faulty MAF can cause a car to run excessive rich or lean7. intake leaks will generally lean cylinders out.8. exhaust leaks before the front 02 generally cause the motor to go rich

Let us know what you find out. I'm curious to know what it's gonna take for you to pass. Or maybe the car does pass and shop just wants to sell you work you don't need. If all else fails, hook up with nifares240. He seems to know a guy.....haha. Good luck

http://carprogrammer.com/Z28/P...y.htm