I failed the HC (PPM):
15 MPH max 36, and measured 155
25 MPH max 47, and measured 55

Vehicle sat in parking lot for 1 hour before they got to it. The techs CLAIMED this wouldn't affect the test results, but I've read that it does. The claim is the cat converter needs to be warmed up for 20+ min before testing (hey, it's on the internet - must be true right?). I've got 29" tires, and don't know if that will affect the results. I'm getting crap MPG: http://bbs.zuwharrie.com/content/topic,93833.0.html, and don't know if it's related.

Bas gas mileage means your ECU is in failsafe mode, one of the various sensors isn't doings its job right, so your engine is running rich, if there isn't a check light on, then start testing sensors.
http://carfix.stufftoread.com/ECU/fail-safe.JPG
http://carfix.stufftoread.com/MPG-not.html
http://carfix.stufftoread.com/sensors/testing-the-sensors.html

I'm going to assume that you've done all the usual stuff: new plugs, wires, clean gas, fresh oil change, etc. It all helps, even the oil change! The cat _MUST_ be hot to work.  Both O2 sensors and CATs gradually wear out over time.  I replaced my O2 sensor at just over 100K miles, just to be sure I had a good one. It actually did improve the readings somewhat.  I have also added denatured alcohol to a tank of fuel (about 10%) and run that for a while (without letting it sit for long) in an attempt to insure a clean fuel system.  Can't say for sure that it helped, but it sure did make me feel better. [And it did work really well on my '85 carburated Volvo.]  California smog tests can be tough-to-pass for an old Samurai like mine.   

I know Cali is out of money but this program should help you out with repairs

http://www.bar.ca.gov/80_BARResources/01_CAP&GoldShield/Factsheets/Consumer_Assist_FAQs.html

Doesn't matter what your income level or anything

I have used it twice - Still get the Code 51 but I did get a new exhaust and cat

Thank you everyone for the links & ideas. Swansen: this is the first time I've seen a writeup like that covering all the sensors - that's SWEEET!

Last year (about 3-4,000 miles ago) I did the 120,000 tuneup. Everything I'm reading points to too much unburnt fuel for the part of the test I failed. So, either too much fuel going in, not enough being burnt, or the catcon not doing it's job. I'll go over everything again (examine plugs, re-do valve adjustment, and check all the sensors & injection). I strongly suspect this failure, my intermittent rough idle (which goes away completely if A/C is on), and low MPG are related.

Anyone out there know how I can test my plug wires & coil to make sure they're supplying enough spark? Anyone seen these, and know if they're good diagnostic tools?
http://www.amazon.com/gp/product/B000AAMY86?ie=UTF8&tag=ecomodcom-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000AAMY86

Anyone seen these, and know if they're good diagnostic tools?
http://www.amazon.com/gp/product/B000AAMY86?ie=UTF8&tag=ecomodcom-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000AAMY86

Check out the thread in the watercooler.

disconnect the battery for about 15 minutes rehook up battery drive for 15 20 miles get retested itll pass the codes will be clear

disconnect the battery for about 15 minutes rehook up battery drive for 15 20 miles get retested itll pass the codes will be clear

Did that 3 days before I SMOG checked it. This isn't a code issue. Something's for sure broken, and needs to be repaired or replaced.

I have had 3 vehicles that have failed emissions I consider my self somewhat of an expert on this topic Bah.  One check your timing make sure it is right on and your ignition coil, wires, plugs, cap, rotor. If your o2 sensor is the original one then i would just replace it with a universal.  Also with the tires being a little bit bigger the emissions guy just puts the pedal to the floor and zuks just don't have the power you may have to tell the tester to do it in a different gear I had to tell them to do that in my 69 baja bug with dual carbs and looking at the test that could be what he did having it at low rpm and a higher gear at low speed he should have down shifted.  And make sure its warm that could also be the reason why the second test is cleaner but still a little high.
If that doesn't work have a diagnosis done at a shop to find the problem.  and then fix it your self saves some money.  I know that my hc's were high when I bought mine the sensor that controls the float I think it was was bad if its carbed, it's on the front of the carb passenger side you'll see the wires coming out.

Okay, I'm following the instructions from Swansen's links & doing my own testing (plugs, wires, valve adjusting etc...). Lots of results, so bear with me...

I did the live scan with OBDII scanner, and the VSS IS working. So that ends that mystery. It's within a couple MPH of what my GPS. I saved the live data, but I'm not sure what any of it means. I think the PCV is out, as the 'ball' freely moves about in there, and doesn't block air flow in either direction (blown or vacuum).

I adjusted the valves. 1/2 were already in spec, and the other 1/2 were within .001. Maybe #4 was out .002 on exhaust side. I added some SeaFoam & ATF to the crank case oil, ran for 50 miles & changed oil. There was a LOUD lifter noise, so I re-checked under the valves and... OOPS! I snugged down all the retention nuts a little more after this. I didn't bother double checking all the other clearances (I should have), because I thought for sure this was the problem. Luckily the adjustment screw & nut were just laying there & easy to retrieve with a magnet:



The ticking seems quieter, but still loud. Can anyone tell me if this is normal sounding to you? 1st vid is before fixing the exhaust-side valve (and smoke from using SeaFoam), second vid is after;





Got confirmation from someone with FSM, feeler gauge goes between cam & rocker surfaces. Good thing 'cause it's hard to get under the adjustment screw (which is where i'm used to putting feeler gauge).

I'd ran the SeaFoam in the gas tank & crank case (about 50 miles - along with a quart of ATF for good measure). Now it was time to run it in the intake side. I pulled the vacuum for the power breaks, but the engine kept dieing (not enough vacuum). So, I put a bolt in there. This also slowed the SeaFoam down, so it didn't stall the engine - worked out great. Got some smoke after re-starting (waited the 5 min), but not much (see video above).

* Timing was off by about 2 deg (running 7 instead of 5 - whatever that means) according to my $14 harbor freight timing light.
* ECT and IAT both tested good
* EGR itself seems to be okay, but the BVSV (behind screwdriver in pic) tested bad (doesn't "open" and let air blow through when heated to 180*F). What's my screw driver pointing at? It looks like a vacuum port, but when I put my fingers on it, there's no suction feeling 


EGR held vacuum, ports looked reasonably clean & diaphragm seemed to work smoothly. I could hear a "pssst" sound when I removed it from the block (pressure or vacuum being released  ):





EGR would stall the engine when I pushed on diaphragm, or if I pulled vacuum. When I jacked the vehicle up (so tires could spin in-gear), and accelerated the diaphragm would move ever-so-slightly. On deceleration, it would move back to the neutral position, but wouldn't move in the other direction (opposite of acceleration direction) as the test said it should. Not sure if this is related to the BVSV failure  Or if something else is the culprit. I did the test in reverse (in case vehicle fell off jack stands, it would move AWAY from me) - not sure if that makes a difference (manual didn't say). EGR passage way to intake is clean (I reamed it out last year), but the intake sure isn't. This is a view of the intake through the throttle... uh... thingy. Look at all that gunk!





* MOD valve thingy was a little clogged. After some cleaning it tests good.
* VSV on front of intake (nearest radiator) with the Mitsubishi symbol tests good, but have no idea how to test the one next to it?
* I didn't test the EGR bypass valve (EGRB) because I don't know which one it is (is it the one in front of intake next to "Mitsubishi" one?).
* I've not tested the ECU, or done much with my scan tool (other than verify no ECU related error codes) because I'm an uber-newb with it.

IAC tested good - um - kinda:
* Stalled when I squeezed 'upper air hose'
* Electric solenoid made clicking sound when 12v applied
* Solenoid read 18 ohms resistance, then slowly read down to 15 ohms (maybe taking 15 seconds to do so?). I thought this was strange. Manual says it should read 11-14 ohms. Then again, I'm such a newb, I'm not 100% confident I was even on the right setting on my multi meter  This is what I was on:





* Manual says testing to ground (on either side of switch - I did both sides), I should get an 'infinity' reading. I got a 1 no matter where I put the probe (engine block, neg terminal, exposed metal on body). Not sure if a '1' means infinity or what 

* Manual says testing to ground (on either side of switch - I did both sides), I should get an 'infinity' reading. I got a 1 no matter where I put the probe (engine block, neg terminal, exposed metal on body). Not sure if a '1' means infinity or what 

The 1 means that the reading is off the scale so if you're on the maximum setting then thats as good as infinity. In the pic you're on the diode test you should be on one of the Ohms settings (lower left). Don't worry if you're an Ohm or two out. What are your fuel trim values and IAC duty cycle?
That engine sounds very noisy to me.

I'm trying to get a replacement BVSV, but I'm having trouble locating one from a local parts store. Can anyone help me with a part #? On my OBDII 16v, it's the VSV screwed to the back side of the intake plenum. Behind the screw driver in this pic, you can see two vacuum lines coming out (the third comes out of the bottom) and the electric plug:



The 3 vacuum ports make it look kinda like an "F". Pictured below is a Toyota version, but it looks basically the same:


The tests from here: http://carfix.stufftoread.com/sensors/EGR/96a-jpg/96a-jpg.zip call it a "Bi-metal Vacuum Switching Valve" or "BVSV".