sparky1562

My 96 failed emissions, twice.

I had the P1445 code last winter, fixed that with a new control valve, see this thread: http://forums.maxima.org/4th-generat...p1445-dtc.html

Replaced front O2 sensor after getting code for that, reset codes, drove for a while, not long enough to get all OBDII items satisfied, so they sniffed the tail pipe.

First trip failed on high HC: reading 244 PPM, limit 220.
CO: reading 0.63%, limit 1.2% no issue.

Replaced air filter which was dirty, checked gap on all plugs (they were fine), reset TB per directions. When I started that, engine stalled, opened up the black screw, set the idle, put everything back together, running great.
Cleaned MAF with MAF cleaner.

Second trip: HC reading 388 PPM (went up!). CO reading 1.69% also went up.
No codes at the time. Had to let it sit for while for medical reasons.

Started looking at it today, had a P0446 coded. Checked the vent valve, seemed to be working correctly, WD40's it anyway, checked voltage okay.
Coil packs all working, no other codes. Checked for intake leaks, exhaust leaks, cant find anything else wrong.

Kind of stumped and looking for suggestions before I give up and take it to a shop.?

asand1

iTrader: (1)

Do you have stock exhaust or y pipe? You might need a new cat. Change oil and maybe plugs.

sparky1562

Have had a Y pipe and new CAT since Jan 08, Oil has less than 1600 miles on it and is not overfilled, plugs are like new (pulled and checked) along with injectors at 180K miles, 40 K miles ago.

what I cant undserstand is I only failed by a little at first, how did adjusting the TB per directions on this site cause it to get worse? Runs and idles better now than before! What I did should have lowered HC.

njmaxseltd

iTrader: (19)

A. WHAT CAUSES HIGH HYDROCARBON (HC)?
Below are common failures which are likely to produce high Hydrocarbon HC. Hydrocarbons are basically raw fuel, otherwise known as Gasoline. High Hydrocarbon (HC) emissions are almost always a sign of poor fuel ignition. However, it's not always that the engine's ignition system is responsible for high Hydrocarbon emissions. Read on.
1. Improper Ignition Timing - Engine ignition timing is measured in degrees before or after Top Dead Center (TDC). Example of an ignition timing failure would be in the case where an engine's ignition timing is required to be set at 10 degrees Before Top Dead Center (BTDC) and instead is set to 15 degrees BTDC. This fault will not only cause a smog check "functional failure", but will increase Hyrdocarbon (HC) emissions as well. California allows 3 degrees +/- off of the manufacturer's required setting. Note: Late model vehicle's may not have a distributor, and therefore no timing adjustment will be needed. On these engines timing is electronically controlled by the ECU (Engine Control Unit).

2. Defective Ignition Components Your vehicle's ignition system consists of the ignition coil/s, distributor*, distributor cap*, distributor rotor*, ignition wires, and spark plugs. If any of these components are defective the engine will produce high hydrocarbons. A common reason ignition components perform poorly is due to carbon build-up. High ignition voltage traveling through the air pockets within these components form carbon. Carbon acts as an insulator between paths of electricity, decreasing the energy required at the spark plug to ignite the air/fuel in the combustion chambers properly. *Distributor-less engines do not have these components.

3. Lean Fuel Mixture - Any condition which will cause unmetered air to enter the intake manifold, and ultimately the combustion chambers, will cause high hydrocarbons (HC). This condition is called a lean miss-fire. Such faults as vacuum leaks and gasket leaks will cause lean fuel/air mixtures. Broken, disconnected or misrouted vacuum hoses will do the same. It is also important to note that many engine components rely on engine vacuum for proper operation. If any of these components are defective, externally or internally, they may cause large vacuum leaks as well. A good example of such a component is your vehicle's power brake booster.


Pick a Type of Smog CheckRegular Smog Test InspectionTest Only or Gold Shield Smog CheckSmog Check Repair Stations
Miles: 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 30 40 50

Which Type Should I Choose?



Failed High HC Emissions
Failed High CO Emissions
Failed High NO Emissions









4. Defective Catalytic Converter - A defective catalytic converter (CAT) may be responsible for high HC, CO, and NOx emissions. The Catalytic Converter, commonly referred to as the CAT is a component designed to continue the combustion process within itself and emit a more thoroughly burned and less harmful emissions containing exhaust. The most accurate way to find out if your vehicle's CAT is working efficiently is by using an exhaust gas analyzer. Unfortunately this tool is fairly expensive. Testing the CAT should be conducted at a smog check repair station.

Some obvious symptoms of a bad CAT could be any of the following:

a. Major loss of power over 15-25 mph. This may be an indication that the catalytic converter is plugged up and restricting exhaust flow.

b. Strong sulfer or rotten egg smell emitting from the exhaust on an otherwise good running vehicle. This may be an indication that the Catalytic Converter isn't burning fuel completely, instead storing it, then releasing it as hydrogen sulfide.

c. Loud rattle being heard from inside the CAT. This may indicate a broken Catalytic Converter substrate. You may want to insure this sound is not due to loose exhaust components, i.e. broken muffler flanges, loose exhaust pipes, loose or cracked exhaust manifold.

5. Defective Air Injection Components - Faulty smog pump and related emissions system components will cause high HC. The air injection system is designed to introduce additional oxygen, after the metering system, to the engine exhaust as it exits the exhaust manifold, or directly before it enters the Catalytic Converter; thus burning whatever remaining fuel (HC) in the exhaust completely.


6. Low Cylinder Compression - This fault is one of the less common high HC causing problems we encounter. Reasons an engine may have low or no compression in one or more of its cylinders may include things such as burned intake or exhaust valve/s, defective valve guides and/or seals, defective piston rings, and burned head gasket/s. A wet/dry cylinder compression test will diagnose this fault. More then often if such a problem exists it will be very apparent. You should notice rough idle.

asand1

iTrader: (1)

1 Stock Y pipe has cats built in. Regardless of how new your cat is, you have less cat than your car was equipped with. If you still have the stocker, install it for testing purposes.
2 Oil collects unburnt fuel (HC) that leaks past the rings, the PCV then breathes those back into the intake. Change your oil.
3 Consider replacing the plugs with the cheapest NGK coppers. Copper has a better spark, at the cost of less service life. "Like new" does not equal new. Change them to make sure you are burning as clean as you possibly can.

Always change oil and plugs before a test, whether its due or not.
These are the simplest and cheapest things you can do to pass your test. Having no codes, you need to do these things first before anything else.

sparky1562

I am familiar with the last two posts, what causes high HC, etc.

The CAT I have is fine, relatively new. The Oil is relatively fresh, and the plugs are fine, I checked them.

Have the Y pipe because the stock pipe was rusted to peices. Has not been a problem to pass emissions since I put it on. I always make sure it is good and hot, and I dont have any codes related to cat or O2 sensors either.

As I stated, I almost passed the first time, with slighly high HC. Adjusting the IACV, putting in a new Air Filter and checking the plugs is all I did, and the HC went way up and the CO went up. Still cant find any air leaks (IE: unmetered), all plugs are firing, no loss of power at all, and running very smooth. No smoke, smells, etc.

Just not sure why the minimal change I made, and checking the other items messed it up worse and didnt make it better!

sparky1562

Okay, I changed the oil, and replaced the othe two O2 sensors since one looked like it was reading funny and they did have 220K on them.

Here is the after recording on my Actron scanner. Idle from frame 1-13, stepped on the gas fram 14-17, returned to idle through 20. (sitting still, not moving).

Comments?

Print Capture Data.pdf

cory420

check your exhaust gaskets. possible leak?

asand1

iTrader: (1)

Are you serious? You really shouldnt spam for your 15 with nonsense.

sparky1562

Did that.

sparky1562

At this point, if someone said check the tailpipe for a banana, I would!

cashoit

u check pcv?

throw some chevron techron in the tank

U sd u had p0446. That is directly related to emissions. U get that resolved?

sparky1562

I ran a scan with only the O2. Under idle they are all low voltage. You can see they rise and fall under throttle around frame 20. leveled out about 10 frames after let off around frame 50.

Question 1: It appears that the car is very lean under Idle and does not fluctuate? (under .45 volts) Is that normal?

Question 2: Should the post CAT O2 keep changing or level out to .45 volts or so under part throttle/1500 RPM. Or keep going up and down with the lean/rich pulses of the pre cat O2's? (like this shows).

Question 3: O2S12 actually had readings over 1 volt, I saw one that was about 1.2 volts. Is that okay/possible?

Cant figure out how to record or print the graphs, but all there show oscillating swings.

Question 4: When emissions stations check with only the OBDII connection, are they just reading that the monitors are set and Okay, or actually calculating something?????

Print Capture Data2.pdf

asand1

iTrader: (1)

I think you are trying way to hard. Shove a wiffle ball in the tailpipe, buy cheapo sparkplugs and change your oil. The fact that you are missing two cats doesn't help.

DennisMik

iTrader: (2)

I was looking at the IGN ADV(°) and comparing it to the ENG SPEED(RPM). I thought that the timing on our cars is 17 BTDC. In the various frames, the ignition is either 11 or 9 at idle and then in frames 13 to 17 when the engine is at about 1500 rps, it is 38 to 36 degrees.

Is IGN ADV(°) not the same as timing?

Roosky

Wow! All i have to say is im glad i dont have emissions where i live

sparky1562

Replaced the other two O2 sensors, drove it enough to set the OPDII ready, and then up pops P0420 and P0430. Maybe I should put the old ones back in....

I think I am going to reset it, try the Denatured Alcohol trick next.
Or sell it to someone one county south of me where they dont have emissions checking.

zach-eminem

iTrader: (1)

try seafoam really well worth it plenty of videos on how to do it you would be suprised at the results i think

sparky1562

I came to that conclusion last night. Going to get some at lunch. Cant hurt.

sparky1562

Seafoamed it yesterday, 420/430 came back. Going to try the denaturaed alcohol before I go further.

Might have to just put a stock Y pipe with pre-cats back in it.

Any suggestions on which one to buy (or not)?

Eastern
Benchmark
Catco
Davico
Walker

Existing large cat is Magnaflow unit I got with the Y pipe. Has 30K on it.
The magnoflow Y pipe is way to expensive!

sparky1562

Bought the 12 MM 02 spacer from 02spacers.com, and was successull in getting the OBDII set for inspection with no codes.
Put 1/2 gallon denatured alcohol in 1/4 tank of gas and went off to the testing station.
They didnt even plug into the OPDII. I guess they dont trust me.
Sniffed the pipe, came up with 200 PPM on HC (limit 220) and .78% on CO (Limit 1.2%) so it passed!
Not sure how much of that was the new parts and adjustments, versus the alcohol. I really think the second reading they got was wrong for some reason.

cashoit

all that matters is that it passed lol

nice!