failed CA smog test

[zer0c123]

My 93 240sx Hatch Manual transmission failed smog today...

15mph 1664RPM

%CO2: 15.3 MEAS %O2 0.3 MEAS HC (PPM): Max: 88 AVE 21 MEA 54

CO (%) MAX: 0.52 AVE 0.06 MEAS:0.13

NO (PPM) MAX: 704 AVE: 150 MEAS: 881 FAILED

25 mph ar 2752 RPM

%CO2: 15.3 MEAS%O2 0.2 MEAS

HC (PPM):Max:53 AVE 13 MEA 38

CO (%) MAX: 0.50 AVE 0.05 MEAS: 0.05

NO (PPM) MAX: 738 AVE:136 MEAS:186

Everything else passed except for emissions. Ignition Timing was at 22 BTDC

I failed the NO test at 15mph, 881 PPM when the max is 704 PPMMy car is basicaly stock, except for an AEM short ram intake. The tech asked me if i had warmed up the car before coming, and i did. Maybe i didn't warm up enough? I drove through the some residential places running the car hard, then i hit the freeway to get the test only station.

I also posted a thread here with my car driving sluggish at low mileage zerothread?id=116104could that have caused me to fail this part of smog?Also sometimes i will smell a rotten egg smell while driving with my windows down. This may have come from a crack that my header has. The crack is located where the pipe connects to the cat, but i'm not sure if this is the problem.

Its been about 3800 miles since my last oil and oil filter change. i doubt this would have made a significant difference.

been about 10000 miles since the distrib cap and rotor, sprk plug and spark wire has been changed (basically a tune-up and engine performance check from a mechanic.

[navysnail]

do a tune up, change oil and filter every 3,000 miles. adjust your timing to 20 BTDC and check EGR for proper function.

[NISTECH]

Adjust your timing to 18 BTDC check your EGR BPT rubber hose for any holes or if its collapsed. You HC is a little higher then norm as well this could indicate a slight vaccum leak which would also bring up your NOx, But you CO was also slightly over the average for your car. This may mean the O2 is getting sluggish. My main thought here is you EGR does not have suffecient flow at lower RPM/load so go for the BPT hose first and see how it looks/feels.

[NISTECH]

Also where in cal?

[zer0c123]

San francisco, CA

when you mean EGR BPT, is it EGR back pressure transuecer right? Also should i even try adjusting the timing without a timing light? I can always get one.

I should also add that the car seems like it wants to stall on cold starts. Like on a cold start after i turn the key, maybe like the first 3 seconds the rpm drops really low but then goes back up to 1200rpm( one time i noticed the clock dimmed really quickly, not sure if its normal), then back to ~700 rpm when the car warms up. When i try to drive, it would be really sluggish until the car is fuly warmed up. This was probably the first sign of trouble for my 240....
Modified by zer0c123 at 5:42 AM 5/26/2005

[180fan]

Retard the timing with a timing light. Without one, you're asking for it. The BPT is the saucer shaped thing at the back of the intake manifold towards the head. There's a little rubber hose under it that runs to the EGR. That hose always gets a hole in it.

[NISTECH]

Yes on the EGR. There is a little black rubber hose under the BPT thats tends to burn through. If it has a hole in it or if it is very soft replace it. I have a feeling that is your main problem. As 180fan said dont set your timing by ear, use a timing light. These 2 things alone should get you through as your readings arent really way out there. As far as your cold run problem it sounds as if it may be getting a bit to much fuel or to little air, this really wont have much effect on your emissions test as the test is suppose to be done once the car warms up nt while cold. BTW its the smog techs responsibility to make sure the car is warmed up for the test,not yours. Its part of the testing proceedure. I know this cause I too smog test cars daily.

[zer0c123]

I pulled out the whole EGR BPT valve today. It was kinda hard since that other saucer thing was in the way along with the other hoses.

Anyway i inspected the hose on the bottom the valve. Visually the part looked somewhat worn on the part where it bends to connect to the other socket. I saw alot of small wrinkled tear marks on the bent part, but didn't look like any hole that i could see. The bent part also felt kinda soft when compared to the other parts of the hose. Furthermore, the inside surface had some residue on it. I shook the tube against the ground, and alot of black crumbs or whatever you wanna call it, fell out. I'll replace the tube on my next day off.

I didn't get a chance to adjust the timing, still waiting for a friend to loan me his timing light.

I did a minor tune-up since i was under the hood.Mobile1 5w-30 synthetic oilMobile1 oil filer300zx fuel filterNGK regular spark plugsdistributer cap and rotor

[NISTECH]

All you did will be benificial to the car and the emissions test. The bpt hose is wasted by your desription, although you did not need to remove the whole egr system. The hose soimply slides off the tube and bpt and you slide a new one on. but since you have it all off take a look in the egr passages and see if there is any carbon build up. If so you might wanna use some carb clean to soak it for awhile then try to clean as much as you can out, this to will help egr flow. The bpt hose is a special hose as it passes exhuast through it so be sure to replace it with an actual BPT hose.

[zer0c123]

The bpt hose is a special hose as it passes exhuast through it so be sure to replace it with an actual BPT hose.

Special hose? I was planning on going down to kragens, and just buying some vacuum hoses. If thats not it, then do i need to get it from the Nissan dealership?

When i looked at the egr it had some kind of material in the middle like a sponge thats visable all around the side. The material looked somewhat worn out on one side, should i still soak it in carb cleaner?

[NISTECH]

NO dont spray carb clean in there, thats your BPT. That sponge is mearly a vent for vaccum when not sending it to the EGR. do nothing with the bpt. The egr is the lower saucer bolted directly into the intake manifold, where that meets the manifold there is a port that you need to look in to see if its all carboned up [black crusty lookin stuff] You may need a mirror to acheive this.

Yea you get the BPT hose from the dealer its like 3 to 5 bucks. Vaccum hose will burn away very quickly dont use it.

[left channel audio]

id say replace you cat. converter if its old you'll gain "or i should say lose" nox points there....

[NISTECH]

his cat is fine, look at his 25 MPH numbers. All readings are good. But at 15 mph his reading are higher.

[zer0c123]

damn it, failed again. I took the car to a shop that a mechanic friend of mine recommended.

The car failed the same part of the test (15mph)This time the NO was at 1000 something. Can't remember the exact #, i just glimpsed at the paper. Also it failed HC too.

He was thinking maybe my EGR just isn't working since i changed the BPT hose. Since the shop is a gold shield station, I just left it there for them to diagnose and fix.

Also my friend that recommended the shop, was kind of suspicious of my cat. When one of mechanics drove the car in to adjust the timing, they heard kind of a grinding sound coming from the car.

One good think is that after the timing was adjusted, the car ran way smoother than before. They just adjusted it to 20 BTDC.

[NISTECH]

thosre guys will find the problem and correct it, Gold shield stations tend to have really good emissions diag guys. Those shops, for those of you that dont know are held to a higher standard then your typical smog shop. They are as close to being state run test and repair facilities as you can get.

[zer0c123]

The smog tech called me today and told me the problem was the tube that connects to the bottom of the BPT hose.Its the weird silver curvy looking one. It was all clogged up because he was getting a weak vacuum test . Therefore it needs to be cleaned.

I actually tried to clean that tube when i was replacing the BPT hose, but it was impossible since its not a straight tube. I tried to remove it, but there was freaking bolt under the intake manifold that was ***** to get to. Eventually i gave up, sprayed some carb cleaner in there and hoped that would do it. The tech told me that even he couldn't get to the bolt, so he will have to remove the whole valve cover or intake manifold to get to it, about 1 1/2 hour labor. Because of that the car is going to be in the shop for another day.

Nistech, you were right about the egr passages. I just wish they were more accessible....