suspendedHatch

Today I had to CA smog my car, and being that this is a common topic, I thought I'd try to make a tech post to help people out. My car is labeled a "high emitter", which means I get to smog it every damn year. For some reason my engine is extremely finnicky with the ignition timing. I barely got it to pass smog last September. NO were sky high as a result of the ignition timing being at 18 degrees (which is within spec). This is where I got labeled as a gross polluter. I brought it down to 16 and it passed. I don't know how long it will be until they forgive me and put me on a regular bi-yearly smog interval.

Some fun facts about my car

- Originally a 93 Civic DX automatic
- ZC SOHC VTEC swap (D16Z6 equiv), never reffed
- the JDM motor doesn't have a vacuum port for the charcoal canister purge solenoid, so I run a vacuum t from the fpr port
- P28 auto ECU from Singapore
- AEM wideband gauge type controller set to 1v output *not smog legal
- DC 4-2-1 header w/ CARB #
- Catco high flow cat converter
- AEM cold air w/ CARB # cut down to a short ram when a hole rubbed through *technically not smog legal
- generic fuel pressure gauge
- Hondata-clone intake manifold gasket
- coolant bypassed from the throttle body and IACV
- injectors serviced by RC


What I find strange is that the engine is at roughly the same RPM for both the 15 and 25mph tests (auto tranny), yet it failed the 25. Driving home at 25 mph, I found that if I forced it to stay in 2nd gear, I ran a near perfect AFR of 14.5-14.9, but in 3rd gear, it was running mid 13's. If anyone can shed some light on this, I'd appreciate it.

The results of this test baffled me because every single maintenance item had been addressed very recently. But then I noticed the report said my ignition timing was only 14. I found that strange as last I knew it was 16 and I couldn't remember ever having touched it. The car hadn't been driven much since my last smog check, but I had tried swapping to a Y8 manifold and back. So at some point I messed with the distributer and then forgot to put it back. When I checked my ignition timing, I found it to be closer to 10 degrees than 14. The smog tech may have fudged his result.

The smog tech told me that I was running rich and it was most likely the O2 sensor. I couldn't tell him that I just installed an AEM wideband O2 sensor only months ago because it's not smog legal. He told me that headers run hot and destroy O2 sensors. This may be true for other cars but was not the problem in my case.


As you can see, I adjusted the ignition timing to 16 and then it passed, but just barely. NO shot up a bit and nearly failed me at 15mph. It seems to me that JDM engines run a bit hotter in the combustion chamber. I may try slightly colder plugs in the future. HCs increased at 15mph but decreased drastically at 25mph.

My reasons for creating this post are as follows

1) possibly help others pass smog
2) see if any smog techs here can shed some further light on my experience
3) show people that it's not that hard to sneak certain technicalities pass the smog tech
4) recommend this particular smog shop to anyone local to me (address is in the pic)
5) encourage others to build on this topic with their smog experiences

sorry to lay that out like a public school worksheet but I'm just trying to keep it short and to the point

forcefedferio

good post i live in PA and i can just get an "exempt" sticker for driving under 5000 miles a year and i never really get hassled on the street, i hope they never start ref'ing cars over here or there are alot of us that are screwed haha

EvilPhu

[QUOTE=The car hadn't been driven much since my last smog check[/QUOTE]
Maybe you got some dead gas

slowcivic2k

If you fail NOX you are running lean in some way, the only time that NOX forms is with high exhaust/chamber temps (1200-1600degrees) If your EGR is inoperative (eventually they clog with carbon) this will make you fail, EGR is there to reduce NOX by cooling exhaust in the intake and thus reducing combustion temps by way if introducing an inert gas.

A typical reading goes something like this:
HC 10-25ppm (ideally 0)
NOX 350ppm or less
O2 0.5% or less
CO2 12-20% ideal
CO 0.5% or less

HC indicates unburned fuel, as im sure you all know.

NOX indicates high combustion temperatures, which is combated with EGR

O2 is your lean indicator, if your NOX is high, odds are O2 will be above normal, making a lean condition the cause of high NOX.

CO2 is your combustion efficiency, when there is enough oxygen present for combustion, it forms the more stable CO2, indicating enough Oxygen available to combust the HC available.

CO is the rich indicator. If this is high, odds are HC is as well, because there is not enough O2 present to form CO2, so it forms CO instead.

Bring your test results in and ill be able to help pinpoint your problem. These people should be giving you a smog sheet, don't take it to a place that doesn't

If its a driveability issue the MIL wouldn't come on, say the EGR passages clogged, but the pintle in the EGR valve still operates, no gas is flowing (or not enough) but the PCM doesn't have a sensor to ensure it gets in the manifold or not. Driveablility would account for 75% of the failures out there.

suspendedHatch

I don't know if you guys finished reading my post but I passed the second time.

Gas was new.

JDM engines and a lot of Honda engines in general do not have EGR.

My problem was ignition timing. Too low and HCs go up. Too high and NO goes way way up. This happens all within +/- 2 of 16 spec.

Eventhough I passed, HC and NO are higher than I'd like.