SDPGreen

Greetings all,

My 1998 Civic EX passed the last few SMOG tests (results below), but she's old & I got a little nervous this time & bought a bottle of CRC brand "GUARANTEED TO PASS EMISSIONS TEST FORMULA, 12 FL OZ".

Guaranteed To Pass® Emissions Test Formula, 12 Fl Oz - 05063

I read the directions stating that after adding the additive to the gas, one should burn a tank of gas, and then fill with fresh gas before testing.

But... I was impatient / curious & tested after burning only about 3 gallons. (free retest)

I failed the test in a big way.

But I do not know if I can attribute the high HC & PO numbers solely to the additive, or if I need to also address other issues???

Oil has just under 3k miles on it (5 months).
O2 sensor: 16k miles( 3 years)
Cap, Coil &Plugs: 24k (4 years)
PCV, I'm not sure about...

I'm planning on at least replacing plugs & air filter before retesting.

Anybody know what test results one would expect from testing with that additive in the fuel?

Given the numbers, any suggestions on what else should be addressed?

Thank you in advance;

mattvivsound

How old is the Catalytic Convertor?

tony_2018

follow instructions

SDPGreen

Hi mattvivsound - Catalytic converter has not been changed since I bought the car - 8 years ago, about 75k miles.

Tony - thanks, I guess? Yes, I'm going to run the tank down and refill.

Does anybody know how to interpret the SMOG numbers - they sure jumped a lot in two years!

• does it seem like the additive could of caused those results?
• do the results indicate any particular action should be taken?

Thank you,
David

super_subie

in two years you only put 10k miles on the car? wow...and it still fails smog?

imo i think the cat is probably the biggest factor; maybe it gave out in the last 2 years?

SDPGreen

HI Super, thanks for the thought.

Correct, low usage recently - I travel a fair amount, work out of home, and live in a very walkable / bikeable area.

I guess I was hoping for a way to diagnose... Would hate to replace the catalytic converter blindly. I got a local quote of $150 for a garage to diagnosis, not including any actual labor/parts. Car runs great, but she's an old beater, & I'm on a tight budget, so trying to do things frugally. I have decent mechanic skills, but not much in way of tools or work space.

Anybody have any tips on diagnosing a catalytic converter? Or how to analayze those SMOG resutls?

Any way to diagnose a PCV?

Maybe I'll repost with a better /more descriptive Subject line.

Thank you in advance.

super_subie

if you can lift your car and go under it, get to the catalytic converter area and tap/shake the piping, if you hear rattling noises inside the pipe it could mean that the insides(honey combo) are all gone/destroy and thus its not filtering anything.

That's what a mechanic guy did to my old car that had a cat problem

civic402lx

Unbolt the cat, look through it. Shake it.

TomCat39

The additive Guaranteed To Pass is supposed to work by somehow preventing the oil on the cylinder walls from burning on high mileage cars.

If it impedes burning, I can only imagine how it impedes the catalytic converter when it's being passed through when burning the fuel with it in it.

Once you refill the tank, the additive is not present to interfere with the catalytic converter.

I would just finish with the directions and retest. If you don't pass then.... THEN ask for guidance. Until then, you are shooting blindly in my opinion.

SDPGreen

Three good tips; thanks Team Honda!! Much appreciated.

I think I'll try to rattle the converter / exhaust to see if I hear anything obvious and, if not, then go with TomCat's thought to run the additive through, refill & retest - in addition to replacing the air filter, & maybe the plugs. Maybe I'll borrow & shine a timing light at her too, although she seems to run fine.

If anybody else out there can decipher any diagnostic info from the SMOG results above, I'd still appreciate more input.

Are there any telltale signs that a PCV valve needs to be replaced?

Probably won't retest until next week or two. I'll post the results.

mk378

Check your spark timing. I'm assuming the car runs OK, that is no noticeable misfiring and no CEL codes.

A PCV valve is a rather simple device. Disconnect the end of the valve connected to the crankcase vent, leaving the other end hooked up to the intake. Start the engine and confirm that air is being sucked through the valve.

Remove the spark plugs and see if they are the same color. One cylinder may be too rich.

Failing all three pollutants usually means the cat is bad.

baller status

You don't know anything at all because of the snake oil. Flush that **** through and run a top tier 87 octane fuel.

Cat converters don't wear out. The notion that "the cat is old, replace it" or that there's some expectation of it being worn out is misguided. If you keep up with maintenance, don't bottom out the car, then you don't need to replace the cat converter and there's no benefit to doing so.

If you have been lax with maintenance, your injectors have never been serviced or replaced, your check engine light has been on for a while and it turns out it's the O2, then you can -
take off the cat
look through it with a bright light to see if the honey comb is intact, not crumbling, not solid
take a small hand torch and cook the insides

This will burn off impurities and make the cat like new again. Do your extended maintenance to address the issue.

SDPGreen

More great & actionable info - thanks mk378 & baller!

Given that I failed 2 pollutants (HC & NO) & not 3, and ballers opinion, I'm thinking a bad cat is lower on the suspect list.

Maintenance - I've been semi-lax. Car has been running well, no CEL, have replaced oil, cap/rotor, plugs as per schedule, but injectors have not been serviced or replaced.

re. fuel injectors, I googled this as symptoms of them needing service. Only symptom I have is the "Failed emissions"...

• Starting issues
• Poor idle
• Failed emissions
• Poor Performance
• Engine does not reach full RPM
• Increased fuel consumption
• Rough engine performance
• Surging and bucking under various throttle loads
• Smoke from the tail pipe

I'll have a look at the extended maintenance list. Beyond burning a tank of (snake oil free) "top tier 87 octane fuel" & intend to replace plugs, air filter, and check timing.

Thanks all!

TomCat39

I understand and agree with what you are saying here. However, you didn't provide all the missing information of what does happen.

True it's not wearing out. But if you burn oil excessively for long periods it coats, clogs and eventually destroys the honeycomb. To some, they may consider this wear even though I think the better word is abuse.

The only thing shown to date to help restore a dirty cat is citric acid bath at 80F for 8 hours. It's been shown to restore catalytic converters back to 80% original effectiveness in controlled studies.

Summary: Catalytic converters don't wear. They do get coated, clogged and damaged.

Side Note: Recent results are now indicating Citric Acid and Oxalic Acid mix for dirty cats.

rfmerrill

Burn a few tanks of gas, try again. If you get the same results I'd say bad cat. Only other thing I can think of would be a dead cylinder (no spark) but you haven't mentioned any performance issues so...

I'm not an expert on this stuff but that crazy huge difference in NOx readings between the two RPMs seems very strange, almost like it's operator error on the part of the smog shop. Like they didn't let it warm up all the way before starting the 15 mph test.

TomCat39

This is a good point too. I recall some buddies telling me when I went for air care to drive at least 20 minutes before going and then keep the RPM up at 2000 or better when sitting in line to keep the cat hot.

Some people shut their car off and it lets everything cool down which works against you.

SDPGreen

Thanks a lot rfmerrill & TomCat! More good tips.

I did drive 20+ minutes before the test, but then, as TC said, the car sat, not running, while I waited for the test.

Agreed to that such a large swing in the numbers seems odd.

I'll burn a tank of gas or two, and make sure to drive a fair amount before, and to keep the car running up until the test.

regarding dead cylinder - no, she runs fine.

regarding timing - she runs fine, and has none of the symptoms below that I Googled. Do you think that means I can rule out bad timing?

"Symptoms of incorrect ignition timing are poor fuel economy, sluggish acceleration, hard starting, backfiring, or "pinging" or "spark knock". Too little spark advance will cause low power, bad gas mileage, backfiring, and poor performance. Too much advance will cause hard starting and pre-ignition."


Appreciate all of the help.