JDM B18c smog (high NOx)!!

[sekondgen]

Hello all, in a couple of days I will be going in for my third ref appointment. I have an OBD1 JDM (P72) B18c in a 93 integra and, as the title says, it wont pass the sniffer test. A quick rundown on my setup: I have the CARB legal Skunk2 IM, stock exhaust (including the manifold), stock intake plumbing with a K&N drop in, USDM GSR ECU, and all of the correct wiring and vacuum lines hooked up, always use 91. Here's the numbers from the first test

15 mph
CO2=14.2; O2=0.6; HC Max=89, Meas=151; CO Max=0.53, Meas=0.64; NO Max=708, Meas=2627 GROSS POLLUTER
25 mph
CO2=15.0; O2=0.1; HC Max=54, Meas=69; CO Max=0.51, Meas=0.16; NO Max=746, Meas=716 Fail

OK so the first test the 15 mph failed miserably. The NOx made me a gross polluter! So after this I did a major tune up. I changed the plugs, oil, checked (and cleaned)the wires/cap/rotor (all recently changed), new cat, new NTK O2 sensor, new pcv valve/hoses and block breather, new fuel filter, ran seafoam on one tank and Lucas fuel system cleaner on another, cleaned the TB and IACV, new thermostat, and used a bottle of HEET in the fuel I used on the second test, and here are the results from all this work:

15mph
CO2=14.8; O2=0.3; HC Max=89, Meas=128; CO Max 0.53, Meas=0.34; NO Max=708, Meas=2731! GROSS POLLUTER
25 mph
CO2=15.2; O2=0.0; HC Max=54, Meas=45; CO Max=0.51, Meas=0.11; NO Max=746, Meas=737 Pass

So I'm getting a little closer, I actually passed the 25 mph test! But now what!? I Know that high combustion temps/ compression yield higher NOx numbers but timing is right at 16 degrees and with all of this new crap I figure it should pass! I have a couple theories as to what the problem is.
1. I didn't wire something correctly that wouldn't throw a code if it were bad (i.e. purge control solenoid)
2. Bad coolant temp sensor? My fan never kicks on and my system has to relieve pressure often (but never overheats/goes passed half way mark on gauge)
3. Vacuum leak somewhere? I sprayed carb cleaner anywhere and everywhere there could be a vacuum leak and there was no change in idle speed. There is however a slight surge when I hold the throttle at any rpm. My buddy brought home a smoker from his shop and we didn't see anything (car was still hot though which sometimes makes it hard to see the smoke)
4. Bad or going bad sensor? Maybe a bad MAP sensor or TPS, IAT, etc?

Sorry this is so lengthy, if you made it this far I appreciate your time. I'm just really in a bind. The DMV said they wont give me anymore extensions and I have a month left. Not to mention I'm kinda broke, so I can't afford to blindly throw money at new sensors and crap that don't need to be changed. If you have any input it would be greatly appreciated.
Thanks,
Eric

 

[newb]

I would check the IAT. It affects timing, so I would think that if it were bad theres a chance it could be pulling your timing enough to make you fail, but not throw a code. Thats just my thought though. Hopefully someone else will have more input. GL.

 

[sekondgen]

I forgot to add to theory number 4. I have an intermittent rough start. By that I mean once every one to two weeks, when I try to start my car, I will have to crank it for a while (up to about 5 seconds) and/or followd by a stumbling start. the stumble only lasts for the first seconds of the initial start up. I had a similar problem in my old teg. It had a B16 and did the same thing (more frequently and ran crappy) for months without throwing a code. Finally it thew the crank position sensor code and I just replaced the distrubutor, which in turn fixed the problem. I figure that the obd0 system is a bit more lax than the obd1 which is why it took months to recognize the problem? I just wish my current setup would throw some sort of a code to give me a smoking gun!

 

[newb]

Now I know this is a totally different car, and its OBDII, but my buddies Z28 has had a few fuel pump problems. On his, the check valve or what ever that keeps the pump primed went bad, and his car would do exactly what yours does. I mean the rough start. And it never threw a code. Think maybe your pump could be bad, makin it run lean? Do you know your fuel pressure or your AFR?

 

[sekondgen]

Now I know this is a totally different car, and its OBDII, but my buddies Z28 has had a few fuel pump problems. On his, the check valve or what ever that keeps the pump primed went bad, and his car would do exactly what yours does. I mean the rough start. And it never threw a code. Think maybe your pump could be bad, makin it run lean? Do you know your fuel pressure or your AFR?

I don't have any sort of a meter or tuning program. Might be a good time to get a air/fuel meter.

I would check the IAT. It affects timing, so I would think that if it were bad theres a chance it could be pulling your timing enough to make you fail, but not throw a code. Thats just my thought though. Hopefully someone else will have more input. GL.

Yeah tomorrow I'm gonna test all of the sensors and poke and prod at a few things to see if I can some results.

 

[red91efhatch]

If you have all the necessary emissions equipment in place then I suggest two options, switch from 91 octane to the lowest octane available, not permanently just for testing and 2. use a product called "Guaranteed to pass" I buy mine at checker autozone etc., use with full tank, run the car to 1/4 tank and then get it tested, note: the product tells you to competely run the tank empty then fill, then test but just ignore that. I get mine to pass that way. good luck

 

[phyregod]

Definitely fix the fan and have it running during the test, that'll lower combustion chamber temps a tad, which will help.

Check over every inch of the head and intake for any vacuum leaks whatsoever. A vacuum leak will cause it to run lean, upping the combustion temps and raising nox..

Also, you might want to try swapping out the JDM ecu for a USDM one for the test. I don't have a clue what the jdm tune is, but I know the japs aren't anywhere near as picky about emissions as the US is. I'd bet the usdm ecu would tame it a bit.

How old is your cat? Could just be worn out or partially clogged. Also the 02 sensor may be reading a bit off and leaning your engine.. Is that old as well?

How did the plugs you pulled look? Chalky white?

 

[sekondgen]

If you have all the necessary emissions equipment in place then I suggest two options, switch from 91 octane to the lowest octane available, not permanently just for testing and 2. use a product called "Guaranteed to pass" I buy mine at checker autozone etc., use with full tank, run the car to 1/4 tank and then get it tested, note: the product tells you to competely run the tank empty then fill, then test but just ignore that. I get mine to pass that way. good luck

I tried that stuff before the first test but I ran the tank completely empty before getting it tested. I'll try it again without burning all of it off.

Also, you might want to try swapping out the JDM ecu for a USDM one for the test. I don't have a clue what the jdm tune is, but I know the japs aren't anywhere near as picky about emissions as the US is. I'd bet the usdm ecu would tame it a bit.

How old is your cat? Could just be worn out or partially clogged. Also the 02 sensor may be reading a bit off and leaning your engine.. Is that old as well?

How did the plugs you pulled look? Chalky white?

As I stated in the original post, I did all of this and much more I'm running the US ecu, brand new cat, brand new O2, brand new plugs.

 

[red91efhatch]

Don't forget Lower octane fuel.

 

[sekondgen]

Got 3 bottles of HEET and 1/2 tank of 87 today . I was pokin around with the multimeter today and I got 4.5 volts going to the MAP sensor when it calls for 5. I'm not very savy when it comes to electrical components but would that be cause for concern?

 

[red91efhatch]

Make sure you are checking the right ones yel/wht + grn/wht- should be 5v unplugged from the sensor, since its 4.5 test yel/wht against a BODY gound -, if there's 5v with body ground then repair the open grn/wht wire (in other words check if the wire is cut, and the connection to D22 on the ECU....also test this at the ECU with d11 and d22 using a multimeter if it shows the same voltage at closed and full throttle then you should be ok anyway.Throttle Closed (Idle) 0.2 Volts 1/4 Throttle 0.5 Volts 1/2 Throttle 1.75 Volts 3/4 Throttle 3.0 Volts Full Throttle 4.0 Volts
but honestly since the sensor only uses 4v max anyway I would say its ok as long as when you test d11 d22 by pushing the pedal down the multi meter should gradually read from 0.2 (or so) to 4.0v (or so)steadily and gradually as you press the pedal. reason I say "or so" is mine reads 0.4 at idle and 4.2 at WOT and my car and emissions are fine)

 

[sekondgen]

Yeah I checked the right ones but it wasn't at idle, the engine was off but the ignition was on. Oh and I failed test # 3! when I first showed up, he kinda took his time getting it tested so it kinda cooled down. 87 and 3 bottles of HEET, a new fan switch, water wetter and the numbers were completely identical. He felt kinda bad so he was cool and let me warm it up at 3k for a few minutes on the rollers and that brought the numbers way down. But the NOx was still about 1400 (still better than 2700!). I think I need to face the music and buy a decent cat. I have a sneaking suspicion the guy who sold me mine gave me a 49 state cat, not a CA legal unit.

 

[DARRENROWE]

you know what? I got the same issue right now, and for some reason my o2 is reading spikes of up to 5 volts?!?! WTF!!! 5 is too high. I got a usdm ecu running the ls engine from 96. I put in an obd2 engine into an obd1 shell, and just ran the obd1 engine management. I got the skunk2 intake mani as well. I also have a distributor from an obd2, but I made a jumper harness to make it work wid my obd1 electronics. I am out of ideas, and out of extensions. One of the old skool import racers told me to run a resistor on the o2 circuit to pass smog. Anyone heard of this?

 

[sekondgen]

Is it a new O2 sensor? Try a new one. I got a brand new NTK (NGK) universal from sparkplugs.com for pretty cheap

 

[newb]

seckondgen, you pass yet?

 

[pappaj]

I went through all of these problems with my rex with a zc. I researched each emmission i failed under then researched probably causes. High nox I also had trouble with, it is a gas that is created when the fuel is burned at too hot of a temp. My car also did not overheat. All I did was retard the timing to about 8 deg. btdc, I know no where near specs. The car ran very sluggish in low rpm's and was a pig on feul, but not a word of a lie, it passed with flying colours. If i can still find the results i will post them and explain what I did to change each emmision. But retarding the timing dropped every emmission by alot. With car sluggish and my etest pass in hand I went straight home and advanced my timing to go fast again.

 

[sekondgen]

seckondgen, you pass yet?

Nope not yet. I go back on Thursday, but this time I actualy have a brand new, CARB legal cat. It's like twice the size of the one I had on before. I really think I got it this time.

I went through all of these problems with my rex with a zc. I researched each emmission i failed under then researched probably causes. High nox I also had trouble with, it is a gas that is created when the fuel is burned at too hot of a temp. My car also did not overheat. All I did was retard the timing to about 8 deg. btdc, I know no where near specs. The car ran very sluggish in low rpm's and was a pig on feul, but not a word of a lie, it passed with flying colours. If i can still find the results i will post them and explain what I did to change each emmision. But retarding the timing dropped every emmission by alot. With car sluggish and my etest pass in hand I went straight home and advanced my timing to go fast again.

Wish I could. Thats the first thing he checks everytime I pull up and anything over 16 or under 14 degrees he'll just turn you away. I forgot to mention I set the timing to 14 btdc for the last test which didn't help any.

 

[pappaj]

When I did my e test they payed absolutely no attention to the timing. I'm not saying to retard it a couple of degrees, I mean a couple few degrees. I'm not shittin ya retard the timing alot and take it somewhere else.

 

[newb]

Or just move to another state, run all the timming you want, no cats, no CARB legal bullshit, and be happy.

 

[sekondgen]

I PASSED!!! The new cat worked...barely. But whatever I passed. so for all those who searched or wanted to know, a GOOD CARB legal cat is key especially when trying to ref a (usually) dirtier JDM engine. I'm sure I could still get the numbers down (NOx still a bit high) but the cat is what really made a difference.