My '83 1500 S...all stock. Brand new cat I stuck on just becuase I usually fail from a bad cat and wanted to nip it before I had a chance to fail.

Well, to my surprise, the car failed.

standard for NOX for high speed: 1678. My car: 3557.

standard for NOX for low speed: 1839. My car: 4084.

Keep in mind this car uses a carb. There's no o2 sensor to replace, the cat is BRAND NEW (1 day old!) and I ran the car hard before the inspection to make sure it was nice and hot.

Any ideas? Car runs perfect...perfect idle and everything. I was shocked that this thing failed.

 

High combustion temps.

Check coolant, check timing (advanced?), run a cooler plug, Seafoam/Deep Creep.

 

As said above, your combustion chamber temps are too high. Does it have an egr valve?(i'm pretty sure it doesnt) The catalytic coverter that you got, is it a three way cat? Definetely check the timing make sure its not over advanced. And check the plugs to see if your runnig too lean.

 

how do I know if it's a 3 way cat or not?

I'm using OBDI approved universal 2" Catco cat.

 

Ok your cat is good then...so look into the other things.

 

Well, turns out this car does have an EGR.

I found a printout on Mitchell to test the EGR function. I'm also going to check the timing and give it a minor tune up.

Hopefully I can get this thing going right.

 

Ahh, ok, its likely the egr may not be functioning properly or there is alot of carbon buildup in the passageways. And like you said check the timing. Because with a brand new cat your nox is way way high. Well tell us what you find out about the egr.

 

Malfuntioning EGR most likely.

 

EGR function was good.

Played with the timing and tested again.

Got the NOX down to ~400/600 and have a new inspection sticker for my efforts.

 

Ahh, very nice!

 

search function ownz.

i just got a 90 Si and tried to smog it and it failed on the nox too, running 87 octane.

what is nox? what causes it to be reading high on the sniffer?

i will check the egr, coolant, timing, and plugs when i get home from work.

i just found our what an egr is last week when my blazer's egr valve got held open by a chunk of carbon(quick fix luckily). where is the egr on a d16a6?

i just re-read this thread. so carbon buildup can cause the hi temps huh...and seafoam is supposed to help with that? how safe is seafoam for a 15 year old motor?

 

well i just got home and looked at the haynes manual and all it says about EGR is that i have to take it to a pro due to needing special tools and equipment. wtf.

in the mean time i'll get some spark plugs and maybe some seafoam....brb

edit: btw is it cool (netiquette) that i hijacked this thread seing that i have the same nox issue, or should i have started my own thread?

 

DONT SEAFOAM!!

while there are a lot of people on here who will vouch for seafoam, but in some cases it makes your life worse. my roomate for example. he seafoamed his a6 and i warned him that maybe he shouldnt, and to this day he still complains that his car isnt running right. it bogs at weird times for no apparent reason, and he says it doesnt accelerate like it used to. and all that stuff that breakes up using seafoam, well it has to go somewhere. and to your oil is where it will go. you can change your oil to help clean everything out, but the only right way to clean an engine is to hot tank it. i would suggest if you are trying to pass emissions, not to seafoam it because it will also cause your car to smoke more. i watched in horror when my roomate did it and his car was emitting huge amounts of smoke, blackish blue smoke, the whole time he was doing it, and even after an oil change it was still smoking on startup.

cliffs notes... seafoam will not help your emissions situation. and it may not help your engine at all. however this is just one persons experience.. obviously i dont have numbers to back up my claim.. all i know is that stuff will never go into any engine that i own.

 

dood i totally appreciate that. i was thinking the same thing. i just had to redo the entire fuel and ignition in my blazer. when i did that i ended up cleaning the intake manifold and i guess some carbon chunks broke loose after the job was complete and plugged the egr valve. so i can picture seafoam breaking up the gunk and having to go somewhere.

i just got back from autozone with bosch platinums and ngk standards. too bad i read this post after. i already got the seafoam. but i also got some **** right next to it, called G2P aka Guaranteed to Pass, in reference to emissions testing. i guess you run it through a tank of gas. it claims to reduce emissions such as nitrogen oxide.

anyone have experience with that?

 

Your SI doesnt have EGR so dont worry about it. What i did to clean out some of the carbon build up was go to a GM dealership and buy whats called "Top Engine Cleaner" from the parts dept. It knocked my NoX number down to an allowable level. It was about $20 for the bottle. Check/adjust your ignition timing!

edit: Use the NGK's and return the Bosch's. I dont know about that G2P crap either....

 

thanks. this Top Engine Cleaner you speak of - how is it applied? in the gas tank? through the vacuum? in the oil crankcase?

 

Put your timing to 16 degrees btdc. You most likely need a new catalytic converter if your timing,cooling system, and fuel injection is working properly. You may nned to clean some of the carbon out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ( o )( o ) &raquo;</TD></TR><TR><TD CLASS="quote">thanks. this Top Engine Cleaner you speak of - how is it applied? in the gas tank? through the vacuum? in the oil crankcase? </TD></TR></TABLE>

Its works just like the "fuel injector" cleaner u buy off the shelf at Kragen. Pour it in the gas tank (with a fresh tank of gas) and run that tank down all the way, then refill and go to get it smogged.

 

****. Failed smog again. Last night I changed the fuel filter, plugs, wires, cap and rotor. Today the pre-test was ok, but then it failed again on the real test. The guy recommended the SeaFoam treatment to clean the top of the pistons.

If I recall correctly, when i read the seafoam bottle it said you can use in the vacuum or gas tank. (hard to remember since i have read so many labels lately). anyway which would be better?

 

Ok so last night I warmed up the motor and pulled the PCV line from the manifold. I took an extra vacuum line and put one end on the manifold and the other end into 5 pre-measured ounces of seafoam. The vacuum sucked up about 90% of the 5 ounces and stalled the motor. 5 Minutes later I tried to start the car. Nothing. After several attempts she finally kicked on at a low 500 rpm idle and finally warmed up to a normal idle, with lots of exhaust smoke.

I let her run for a while until the smoke thinned out and then went for a drive. Then I changed the oil again. Well it's 1pm here and the smog test guy is MIA....waiting for him to return to I can pass this test and register my commuter.

oh btw that seafoam is somethin else! i was worried, but not only is the valve tick much quieter, but the motor sounds better and feels a tad smoother. can't wait to see how she does on the smog test. again.

 

check your O2, this sensor is what tells your ecu to add or subtract gas, you can have a dead O2 sensor and the check engine light will not turn on as in OBD2 controlled engine. when I get failed cars that come in the first step I do is check the O2 signal to make sure is there and switching at the right speed (100ms) or less I use a DSO digital storage oscilloscope. NoX is caused by:High combustion temperatures,overly advance and/or retarded timing,engine running hot,lean condition. you also got to look at the other gases to give and idea of how the engine is functioning. if you can post your other four gases I can get a more accurate answer.

 

the reason i haven't suspected the o2 is because my understanding was that if the o2 was bad, it would go into limp mode and run rich. also, i figure this 15 year old motor has a lot of carbon buildup and i'm hoping all that smoke that blew out the exhaust with the seafoam treatment helped with that.

pretest 1 - only changed air filter and oil
PRETEST1 rpm co2 o2 hc co no
15mph 1977 15.3 0.0 16 0.01 999(fail)
25mph 2122 15.3 0.0 14 0.02 548

pretest 2 - passed - changed fuel filter, plugs, wires, cap, rotor
PRETEST2 rpm co2 o2 hc co no
15mph 1910 14.9 0.2 68 0.05 803
25mph 2145 14.9 0.1 47 0.01 816

test 3 - 10 minutes later
PRETEST3 rpm co2 o2 hc co no
15mph 1890 14.8 0.2 58 0.06 807
25mph 2089 14.8 0.1 23 0.01 983(fail)

 

FAILED AGAIN dammit.

i'm just gonna get a new cat i think. maybe an o2 as well.

**** man. "if it has **** or tires, you're gonna have problems with it."

 

Bad EGR.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hazw8st &raquo;</TD></TR><TR><TD CLASS="quote">Bad EGR.</TD></TR></TABLE>

Too bad his model civic (Si) doesn't have one. Its pretty much all about ignition timing and carbon buildup.