my vx just failed smog

[rx7will]

I have a federal civic vx, the one with lean burn. It has 240k on the original engine and transmission. Engine compression is good, tuned up recently. Ignition timing is correct. Engine runs good and does not burn oil. The car already has an replacement catalytic converter installed. I took it apart to fix an exhaust leak and the cat looks good, its not clogged or anything.

I live in San Francisco and we have the enhanced smog. I failed the 25mph test , but it passed the 15mph test easily. I forget to get the print out, but the only thing that it failed on was hc. Mine read around 250, which is gross polluter status. The CO and NOX was was very low. The smog tech thinks it might be a lean miss fire.

So my question is does lean burn kick in at that low of a speed? Usually if the car pass the low speed, it can easily pass the high speed. Is there anything that i can do to turn off the lean burn feature for the smog test. To see if indeed it is a lean missfire caused by the lean burn. We tried to adjust the timing but it did not effect the hc reading. Has anyone else fail on just the high speed hc, but pass everything else?

[Jay2TheRescue]

Sorry to hear about your emissions problems. I remember when emissions testing first came to my area. The Buick failed miserably. I had to buy a new carbureator at $1,200 to fix it and make it pass. I'm glad its exempt now. I'm sure it needs a new carb again, but I think this time I'm just going to put a normal carb on it and ditch this expensive computer controlled crap that doesn't work. Rusty's latest emissions test proves that an old vehicle with a carb can still pass emissions with pleanty of margin to spare.

-Jay

[1cheap1]

Just smogged my 94 intrepid with no new items at all in the last 4 years or so. It passed with no problem. Original converter,pipes. What i did was drive it for about 30 to 45 minutes before the test. You might have thought of having it smogged out of the Frisco area. They are nuts in that city. You did a lot to your ride and it should have passed with no problem. Maybe put in hotter plugs use higher octane, just some thoughts. The Intrepid has 167k on it and is seldom driven.

[bugsih]

keep it in 1st gear, there is no lean burn in 1st gear according to my dmm in my vx.

[Jay2TheRescue]

Originally Posted by 1cheap1

Just smogged my 94 intrepid with no new items at all in the last 4 years or so. It passed with no problem. Original converter,pipes. What i did was drive it for about 30 to 45 minutes before the test. You might have thought of having it smogged out of the Frisco area. They are nuts in that city. You did a lot to your ride and it should have passed with no problem. Maybe put in hotter plugs use higher octane, just some thoughts. The Intrepid has 167k on it and is seldom driven.

Yes, that is always good to do that... The last time I had to get the Buick to pass emissions I did that. I took her out on the interstate and ran her at 80 mph for 20 miles. I then pulled off the highway, and into an inspection station. I left it running in the parking lot until they could get it in. The inspector was suprised and told me he lost a bet because it passed.

-Jay

[Reborn996]

Hmm, I just recently smogged my VX here in the bay area with the Federal ECU and it passed no problem. The car had 200k miles with only the basic tuneup stuff done. What causes high HC??? I would look that up online to see what fix is recommended...

Hycrocarbons (HC)*
A list of common causes of HC related smog check failure:

1. Ignition Timing Advanced above specifications.Timing is measured in degrees. before or after Top dead center. If your vehicle is required to be at 10b degrees and instead is set at 16b degrees your HC emissions will increase. ( b = before top dead center ) .

2. Ignition system problems. Parts like the ignition coil, distributor cap, distributor rotor, ignition wires, spark plugs.

3. Vacuum leaks, Gasket leaks that cause vacuum leaks. Broken, disconnected or misrouted vacuum hoses.Vacuum component failure such as a power brake booster.This causes a very large vacuum leak.

4. Catalytic converter failure.

5. Air injection system problems. ( Smog pump and related components )

6. Engine damage (burned valve, low or no compression in one or more cylinders).

7. Sensor problems and or computer problems can cause a Smog Check failure.

You could go on and on for a few more pages, but these are the main causes.

[rx7will]

I am not sure if i can run the test in first gear because the smog machine wants the test to be done in a certain rmp range, so you will have to change gears.

The timing is correct, we tried to retard the timing but it did not help.

Tune up parts are good, but will recheck and check the fuel pressure.

[mkiVX]

swap in a cali ecu and you will pass with flying colors
federal ecu will not pass

[rx7will]

I dont want to buy an ecu just to pass smog. I have not looked at the wiring diagrams yet, but if i can disable the "lean burn" than my federal ecu would be like a CA ecu. Or if i can turn my 5 wire o2 sensor into a 4 wire sensor. If the check engine light comes on, it does not matter. The catalytic converter was properly warmed up, plus we tried four different times on the smog machine.

I double checked the tune up parts, and decided to change the distributor cap, rotor and ignition coil. The coil looks like its going to crack. It probably wont affect the smog, but it needs to be done.

[suspendedhatch]

Lean burn on this engine doesn't cause a lean misfire. And a lean misfire doesn't cause high HC, it would instead cause high CO.

No you can't run it in 1st gear because it has to be at 2000 RPM.

They already heat it up as part of the test so the old "run it on the freeway in low gear" doesn't apply.

I passed just fine with a federal ECU in San Diego. Passed with over 220k miles and w/out doing any maintenance upon buying the car (was planning my now completed engine swap).

Lean burn will give you high NOx, not high HC's. HC's are partially burned fuel. You're not running rich cuz your CO is low. So most likely your problem has to do with the ignition.

I know you said your ignition timing was done but was it done to VX specs? I know most Hondas are 16 degrees base timing but the VX may be 12 I'm not sure. If it is in fact correct then try the high side of spec. You can go 2 degrees advanced. This may raise NOx though.

Run 87 octane. Change your spark plugs and ignition rotor. The VX uses different spark plugs than what the auto parts stores are going to want to give you (DX plugs), so research it yourself first. Get NGK or Denso brand only.

If you wanted to force it into 16 valve mode (not recommended) you could apply 12v to the VTEC solenoid. This will help your NOx but not your HC's. In fact it will most likely increase your HC's.