PCA SDR

Oh, it is that dreaded time again and so I wonder. What is the best way to improve your chances of passing a smog test. I am not too worried as it is my Boxster S this time and it is stock. But what improves the odds? There are those cans of mystery liquid that claim to help if you pour them in your gas tank. Clean the air filter? Take it out? I have heard you should make sure the car is hot so the catalytic converters are working optimally, and I have heard contrary advice??? Any hints?

Get an OBD2 tester and use it to check the status of the emissions equipment (Secondary Air, Catalysts, etc.) This is the same info that the Smog tester will query, and if more than one or two of the subsystems reports "not ready" (not sure of the exact number), they will not pass you. If you have recently disconnected your battery or cleared a CEL light, don't panic if some or all say "not ready", as the car has to go through the full emissions driving cycle before the ECU will set the "ready" flags for the various subsystems. Conversely, if all the flags come back as "ready" (don't worry about "not applicable" flags), you're golden. (With 4 catalytic converters, your car will not fail the tail pipe test unless there is something wrong with the engine).

You will also have trouble finding somebody who is willing to smog a Boxster, so let your fingers do the walking and call a prospective shop and ask them ahead of time. The ones that do will either charge you more money (because the engine is hidden and hard to get to), or maybe not even look at the engine, or very possibly both. (I even showed one shop how to open a Boxster engine compartment, and when I came back two years later, they wouldn't take Boxsters...)

I just smogged my wife's PT cruiser. (ok, ok, I know). The check engine light was on. I used a tester to clear the code, since it was for the EVAP system and did not affect the tail pipe emissions. A few months ago we had replaced the battery.
It failed because four of the systems were not "ready".

It turns out that to get some of the systems "ready" you must drive CONTINUALLY for at lest FIFTY miles.
The mechanic told me to drive it to Alpine and back and have it retested.
That did the trick and it passed.

Russel, what type of tester will tell you the status of all the systems? The one I have only shows malfunction codes.

Yes on some cars a warm CAT will help lower the emissions.

Anyone have any experience with fuel additives that supposedly lower emissions?

gocart wrote:I just smogged my wife's PT cruiser. (ok, ok, I know). The check engine light was on. I used a tester to clear the code, since it was for the EVAP system and did not affect the tail pipe emissions. A few months ago we had replaced the battery.
It failed because four of the systems were not "ready".

It turns out that to get some of the systems "ready" you must drive CONTINUALLY for at lest FIFTY miles.
The mechanic told me to drive it to Alpine and back and have it retested.
That did the trick and it passed.

Russel, what type of tester will tell you the status of all the systems? The one I have only shows malfunction codes.

Yes on some cars a warm CAT will help lower the emissions.

Anyone have any experience with fuel additives that supposedly lower emissions?

you are referring to "readiness codes".
Readiness codes exist to prevent someone from clearing a CEL and then driving to smog center for quickie test.
readiness codes requires that you perform a specific drive cycle to set the codes
FYI P car readiness codes are typically much harder to reset than just driving 5o miles, there are many threads on RennList if you care to check them out.
Agreed, hot cats are typically good to pass smog with, but the smog test protocol may preclude this option.

Fuel additives lowering emissions????????? a chemist may be able to blend a fuel that would help, but i doubt you'll find anything at pep boys that does anything other than
lighten your wallet.


cheers

Craig

gocart wrote:Anyone have any experience with fuel additives that supposedly lower emissions?

I actually had my wife's Miata fail a smog test marginally one time with an NO2 reading that was a little bit high. The guy told me to go put a can of octane booster in the tank, drive it around a little and come back. He retested it and it passed. I wouldn't have believed it if I hadn't seen it.

TT

gocart wrote:
Russel, what type of tester will tell you the status of all the systems? The one I have only shows malfunction codes.

I have an Actron CP9135. Menu item #4 is "I/M Monitors" and it scrolls through all the emissions subsystems flags to see if they are "ready".

lrayner wrote:Oh, it is that dreaded time again and so I wonder. What is the best way to improve your chances of passing a smog test. I am not too worried as it is my Boxster S this time and it is stock. But what improves the odds? There are those cans of mystery liquid that claim to help if you pour them in your gas tank. Clean the air filter? Take it out? I have heard you should make sure the car is hot so the catalytic converters are working optimally, and I have heard contrary advice??? Any hints?

Assuming your Boxster is well maintained and in good working order (no CEL) you should have no worries. Jusy make sure you have fresh gas in the tank and get in a little spirited driving for 15-20 minutes before the test to clear out the cobwebs and carbon in the cylinders and cats . My lil 98 still runs clean as a whistle with emissions far below requirements in CA. Most inspection stations I have used don't bother to open the engine cover. They inspect for tampering with a mirror from underneath.

ttweed wrote:

gocart wrote:Anyone have any experience with fuel additives that supposedly lower emissions?

I actually had my wife's Miata fail a smog test marginally one time with an NO2 reading that was a little bit high. The guy told me to go put a can of octane booster in the tank, drive it around a little and come back. He retested it and it passed. I wouldn't have believed it if I hadn't seen it.

TT

In regard to NO2, one of the best ways to avoid issues is:

A) New spark plugs
B) De-natured alcohol (basically methanol) at a 25% solution to gasoline (This does the same as adding octane boost. The trick is not to add too much as the carbon emissions go up as NO2 goes down).
C) check/re-check timing if you have pre-DME managed engine.

The stuff in the can G2P (Stands for Guaranteed to Pass) is mostly denatured alcohol. Alcohol retards the burn ... much like octane boost, and also reduces temperatures inside the combustion chamber; improving NOX but increasing CO.

If you add G2P or octane boost or de-natured alcohol you should go to the gas station immediately after the test and fill her up with regular (91 octane ok) gas to dilute the additive. The car will lose some power under the influence of additive. You will restore the power with a fresh batch of gasoline.

BTW: De-natured alcohol is sold at your local Home Depot or hardware/paint store by the quart. It's usually in the paint and thinner section.

That's been my experience ... Happy smog-test!

thanks everyone. It is on my "to do" list for this week.

It passed easily I used Vista Way Smog, a test only station at 911 (good omen) East Vista Way in, you guessed it, Vista. The tech there is Leslie and, if you help him figure out how to open the engine compartment, he is happy to test Boxsters or other Porsches. He fondly remembers the ride I gave him two years ago, when I last had to smog the Boxster. It was $42 with a coupon from the Pennysaver.

So took one of my 944 projects to smog and it failed NO with measured rates of 879 against a max of 795 at 15mph and 1181 against 676 at 25 mph. If I understand all the other posts and Dan's specifically. I should add denatured alcohol up to 25% to fuel to drop NO. Other measurements were virtually zero, actually CO was zero at 25mph.

Brian,
Was the Cat good and hot. It's my understanding the NOX is the cat. Mine failed also, but I haven't taken it back.

I felt it was hot, car was running for about 45 minutes with some spirited driving on the way to smog. I never shut it off until after the test. Car has been sitting for 10 years-cat could easily be shot though...

If your CO was zero and your NOx was high, it may be that you are running too lean. NOx usually indicates that your combustion temperature is too high (i.e. lean).

harnishclan wrote:So took one of my 944 projects to smog and it failed NO with measured rates of 879 against a max of 795 at 15mph and 1181 against 676 at 25 mph. If I understand all the other posts and Dan's specifically. I should add denatured alcohol up to 25% to fuel to drop NO. Other measurements were virtually zero, actually CO was zero at 25mph.

Brian
Your fuel (C.O.) cools off the cylinder and lowers NoX. First put a DVOM on the black wire of the O2 sensor and check voltage. A cold engine should read a steady .450 volts. Now raise the RPM to 2500 and after 3 minutes it should swing rapidly from .200-.800 volts. If it swings slow or doesn't swing at all you need an oxygen sensor.

After you repair it you will need to give the car a really good drive below 60% throttle to get the cat to light off. Lots of 1/2 throttle 5th gear work should do the trick.