I was looking at this thread: https://honda-tech.com/zerothread?id=1827227

I failed smog this afternoon. High NOx on the 15mph. I made sure to drive for about 10 minutes on the freeway to get the cat hot.


Specs on the car:
1994 Civic EX coupe 5spd, D15B with all of the D16Z6 intake and emission stuff (bought it like this but it passed when I bought it, should I go get it bar'd?)
edelbrock proflow header, less than 1k miles
NTK O2 sensor, less than 1k miles
direct fit magnaflow cat, less than 1k miles
ngk iridium spark plugs and ngk wires
87 octane fuel, chevron
timing is 12BTDC
about 45k on the engine, chassis is 140k

As you can see the timing is 12BTDC. The high NOx doesn't make sense, usually if CO and HC are elevated, that means the car is running a bit richer than normal, and more fuel should mean cooler combustion and lower NOx. Or am I not getting complete combustion? If I were to retard the timing 1 or 2 degrees, then that would lean it out even further and cause higher combustion temps, would it not? I'm going to change the spark plugs back to NGK coppers, and possibly put the stock cat back in. Would that guarenteed to pass stuff work in my case? Any suggestions? I'm leaning towards the cat itself because all the levels are elevated acrodss the board on the 15mph. This is a headache.

 

right before smog turn on ur heater and let the hot air out. and try putting high octane.
heat up the car right before smog. rev it around 1.5k to 2k for few mins.

good luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BUNNYz &raquo;</TD></TR><TR><TD CLASS="quote">right before smog turn on ur heater and let the hot air out. and try putting high octane.
heat up the car right before smog. rev it around 1.5k to 2k for few mins.

good luck. </TD></TR></TABLE>

I never thought to use the heater trick to cool the engine. I initially had it all the way cold to heat up the engine faster, but didn't turn it on full hot for the test. I'll have to keep that in mind. Not a lot of places if any do no pass no pay anymore, so I do not want to have to keep on paying the money to get it retested. Thanks for looking out.

 

Would running the colder ZFR6J-11 plugs be better than the stanard ZFR5J-11? I really dont think the spark plugs had anything to do with it, I had the ngk iridiums in before, the ZFR5IX-11; I just changed out the plugs back the the coppers and it seems to pull a little harder, but ambient temperature has gone down about 5degrees so that could hav been it. The iridiums I pulled were all perfect in color on the ceramic, no fouling or excessive carbon buildup on the thread part.

 

i dont think higher octane is giong to help. your co is quite high. its really close to max, is stock timing really 12'before top dead?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by frankist &raquo;</TD></TR><TR><TD CLASS="quote">i dont think higher octane is giong to help. your co is quite high. its really close to max, is stock timing really 12'before top dead?</TD></TR></TABLE>

i'm not sure i'll have to check the emissions sticker on the hood. I know it probably not going to fix it but would getting a chipped ecu help pass smog (cars obdI so i ont think theres anyway to tell unless its opended)? With appropiate basemaps etc for a stock config.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by frankist &raquo;</TD></TR><TR><TD CLASS="quote">i dont think higher octane is giong to help.</TD></TR></TABLE>
Naw, me neither....

 

Put the timing back to 16 degrees and use the P08 maps in your ecu. The D15Bs fuel maps are lower and the timing is different.


Use the right map for the engine.

 

could be build up on your piston heads. I failed nox miserably last smog, took it back to the shop, did a little diy water injection and took it back next morning and it passed with flying colors

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by F20Cteg &raquo;</TD></TR><TR><TD CLASS="quote">Use the right map for the engine.</TD></TR></TABLE>

You got the right idea!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by F20Cteg &raquo;</TD></TR><TR><TD CLASS="quote">Put the timing back to 16 degrees and use the P08 maps in your ecu. The D15Bs fuel maps are lower and the timing is different.


Use the right map for the engine.</TD></TR></TABLE>

Right now its on a P28 ecu (stock d16z6 ecu). Would it be easier to just purchase the p08, or get my p28 chipped (I was thinking phearable, etc) and then base-map it from the p08? Oh and I checked the timing, it's spot on 16, the guy at the place must have misread it or was looking at an odd angle.

There is hardly an rpm difference between the 15mph test and the 25mph test, even though I had the car idling the whole time before the test to keep the cat hot, at idle cat temps can drop to 350. The op temp is somewhere around 500-600 from what I understand. My guess is that because the 15mph test was right before the 25mph test, this allowed the cat to come back into operating temp. My plans right now are to get a larger magnaflow cat installed if the oem one doesn't pass me. But if just chipping/swapping ecu would pass, then this might be the more viable option.

 

[QUOTE=chrisw85]

Right now its on a P28 ecu (stock d16z6 ecu). Would it be easier to just purchase the p08, or get my p28 chipped (I was thinking phearable, etc) and then base-map it from the p08? Oh and I checked the timing, it's spot on 16, the guy at the place must have misread it or was looking at an odd angle.
[\QUOTE]

Cheaper to get your ecu chipped. Phearable does good work, he uses the same exact equipment that I do to chip ecus. Hakko all the way.


High NOx comes from lean mixtures or too advanced ignition or cat not working. The P28 ignition maps are advanced in many places, some by as much as 4 degrees.


Get new spark plugs, gapped correctly and use the P08 maps. You should pass no problem.

Good luck, Merry Xmas

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chrisw85 &raquo;</TD></TR><TR><TD CLASS="quote">

Right now its on a P28 ecu (stock d16z6 ecu). Would it be easier to just purchase the p08, or get my p28 chipped (I was thinking phearable, etc) and then base-map it from the p08? Oh and I checked the timing, it's spot on 16, the guy at the place must have misread it or was looking at an odd angle.

There is hardly an rpm difference between the 15mph test and the 25mph test, even though I had the car idling the whole time before the test to keep the cat hot, at idle cat temps can drop to 350. The op temp is somewhere around 500-600 from what I understand. My guess is that because the 15mph test was right before the 25mph test, this allowed the cat to come back into operating temp. My plans right now are to get a larger magnaflow cat installed if the oem one doesn't pass me. But if just chipping/swapping ecu would pass, then this might be the more viable option.</TD></TR></TABLE>

Quit thinking RPM and think more about load. Thats the point of the different speeds.. to load the engine differently and test under those conditions. You have the wrong maps for the car and it could very easily be the reason why you are failiing. The cam profiles in the D15B are different from the Z6... enough that the ignition maps could be the source of the problem Iridium plugs last long, they don't make more power and have actually lost power in my personal testing on the dyno. Not much, but power is power. I have ALWAYS used stardard plugs since the test as a result.