97 Q45t failed smog

[miata007]

Recieved DMV annual renewal and requires me to get my Q smog. Took it to a smog station on Sat and failed with HC over the max value.

Recently my car had a CEL..diagnosed with OBDII and replaced TPS. Fixed the CEL and car ran fine. Car hasn't been tune up in a while but here are more info.

1. Oil change every 4000 miles.2. KS replaced 3.5 years ago.3. New coils last year.4. Fuel filter replaced last year.5. TPS replaced 2 months ago (fixed CEL).6. Almost always go with Chevron/76 Super unleaded.7. air filter was replaced 2 years ago (need to replace!!).

Anyone has ideas why HC levels are hi? The rest of the test are passing.Many years ago, my CRX failed smog. I got a bottle "Guaranteed to Pass" from Pepboys and got it to pass. This is a fuel system cleaner. Put it in last nite on a full tank. Planning to take the test again this weekend.

In the mean time, I will replace the air filter, check spark plugs and what else???

Thanks007

[Victor]

Some things that help pass smog tests. !. Make sure the engine is thoroughly warmed up, take it on the freeway if necessary. I failed smog once and the guy told me to ride around for a half hour and then come back, it worked. Keep your engine running while waiting so it doesn't cool down.2. Make a hole in your exhaust pipe. If the guy is lazy and doesn't notice it the fresh air mixed with the exhaust will make you pass with flying colors. My van has a hole in the exhaust pipe and always passes with amazingly good results.

[maxnix]

When was the last time you completely cleaned your EGR valve? The down tube to the collector? The tube inside the plenum?

Hole in the exhaust makes not difference as pressure is on the inside of the exhaust pipe. That reasoning is like the guy tearing up newspapers and throwing them out the window to repel elephants. He thinks since there are no elephants present, it must be working! A classical non sequitur.

[miata007]

Since I've got the car at 120K (now 202K miles), I have never clean the EGR. Is that the one that requires removal of the plenum? I am really hoping I can avoid that.

007

[maxnix]

Tube in plenum does require plenum removal. It becomes filled with carbon and flow is obstructed, At least try cleaning EGR valve.

In my experience, you are way over due for KS, hoses, IAC and TB cleaning, and Plenum and lower runners cleaning. You will be surprised how much better your car will run.

Read ParanoidJack's thread.

When did you last replace your fuel filter?

[Q45tech]

If O2 are new then the cats are always the next components to examine and test especially if the HC is just a little above max.

200K is a very long time for OBDII [after 1995] cats.What was HC reading for the 2 different rpms?

[miata007]

I can't recall what the HC reading was but did remember it was quite high, not just a bit over.

Fuel filter was replace last year.KS was replace 3.5 years ago.O2 sensor: haven't replace it.

I believe there are 4 O2 sensors, is there a way to determine which one is bad? Sorry I haven't look at the FSM regarding to this topic.

If it is the cat converter, I am not sure if it is worth the fix. I may consider junking the car and try to qualify for the car stimulus plan ($3500 to $4000).

Does anyone know you can qualify if fail smog? I only have til middle of July to get my smog done. So must act quick for that route.

007

[maxnix]

Time to get an OBD II scan, record codes and reset the ECU.

Unless you have cash coming out of the kazoo, probably a better deal to address the deferred maintenance and run it 2 or 5 years until a real hybrid or dominant electric car technology emerges. NAtural gas is being ignored presently despite a mature technology and a surplus of resources for the time being.

[miata007]

Max,I am not following. Do you mean if I use the scanner and reset the ECU, miracles will happen the next time getting a smog check?

I've used the scanner 2 weeks ago without reseting ECU and everything was ok. No CEL.

Here are the results of the failing smog test:

rpm HC (max) HC (ave) HC(meas) 15 mph 1430 47 9 7325 mph 1449 31 7 85

CO and NO measure values are pretty low.All visual inspection and func check are passing or N/A.

007

[BadQ45t]

I d not know where you live but you need to find a good and honest mechanic that has access to the smog system. I have a good one in LA and one in the Bay Area....you need a very trustworthy one as they can fleece you in this scenario pretty quickly, but the suggestion to "drive it for awhile and wait for hybrid" isn't going to help you drive it without tags.

Where are you lcoated, there are lots of guys on this on the board with good recommednations. Stop throwing @#$@ at the wall and find someone that can narrow this down quickly with access to the system.

My 97' has 92k on original KS, packs etc and passed in May with more than flyng colors, clean as a whisle.

[maxnix]

Difficult to believe it won't pass but still doesn't throw an OBD II code.

Start with the EGR valve and tubes. Inspect, clean, and report back.

[NightRiderQ45]

Remove your plenum if you want...and you will have more issues than you have now!

[miata007]

Have some updates from over the weekend.The HC value at 15mph is now passing at 46 (was 73).The value at 25mph is failing at 33 (was 85), so failing by 2 point/units.

original smog result:rpm HC (max) HC (ave) HC(meas) 15 mph 1430 47 9 7325 mph 1449 31 7 85

Here's what I did to make the improvement.1. replaced air filter2. drove the car for 30min on highway before smog check. Let the engine on as well before tech took my car.3. Add a bottle of "guarantee to pass" fuel system cleaner from Pepboys.

I was happy with the improvement. Too bad one of the test is still off by 2 points. The tech also recommend me to change the spark plug is they are old.

I can't recall how long I've had them replace. Probabyly 3 years ago.

Does any one know what is the NGK part # for Y33? In the past, I've ordered from IOS but didn't want the long wait right now. Do you guys know Pepboys/Kragen carries the same plug?

Thanks007

[Q45tech]

13 years is a long time for OBDII cats by design they are of a different structure and metal composition. Than 90-93 or 94-95 cats [due to different emission minimums.

Also the Q41 was a decontented [cheaper version $10,000 less] of the earlier Q45 so you would expect cost cutting everywhere.

We are seeing a number of 2001 and 2002 Q cats that are failing just after 120k.................as expected.

[BadQ45t]

Really cats failing after 120k!!!!! Can we get aftermarket ones yet or do we need to give Infiniti 2 grand for two of those puppies?

My 84' Z's cats lasted until 2006 at 159k, I have 92k I guess I better put new cats on the shopping list!

[Q45tech]

OBDII CATS are very different from OBD cats.

With most after market OBDII cats you are lucky to get 2 years service before they fail.............read the fine print in warranty.

My 1990 cats are still passing the very very very looser 1990 standards.

.................max CO%....HC ppm......................typical CO typical HC1981-93..... 1.0-2.5... 200-300................... 0.0-0.5... 10-50

1994 & 95....... 1.0-1.5..... 50-100.................. 0.0-0.2.... 02-20

Even the 1994 cats on a Q45 are different and less robust

Hopefully you can see that a 90-93 Q can pollute 10x more than a 1997 in HC

[BadQ45t]

I guess I'm lucky with a 97' that still is clean as can be, no where anywhere near a no-pass last time...12 years and counting.

So do you have to buy Infiniti ones or are decent aftermarket ones out there. My brother has to drop 1.5k on Lexus ones on his 96' but he's got 210k.

[3Q Jay]

you are very close.don't go to pepboys.get the pfr5g-11. joe may still have a special. other choices are sparkplugs.com (a sponsor--use 'nico10off' in the coupon field).

check your timing with a light and if right around 15 btdc, try setting it to 13 (careful--they may check it and lower tolerance is 12).

[Q45tech]

HC IS THE amount of UNBURNED GASOLINE in exhaust reducing ignition advance makes the engine burn even less since the spark occurs later in the cycle.

The length of cats changes the TIME relationship between the front O2 and rear O2 but that is primarily a MIL light setting situation not an actual measured on emission dyno situation.

An expert should be able to measure each bank independtly and determine which cat is the worst [probably passenger side but don't count on it] so you have less to change to pass.

[miata007]

What's the difference between pfr5g-11 and my current ones.

I''ve inspected couple plugs on my car last nite. They looked ok. Not oily or highly corroded after 3 years (??). The # I got from the plug says: pfr6g

I got those plugs from Joe. Did I get the wrong plugs or something?

I am hoping pepboys will have the same exact plugs so I don't have to wait over a week for shipping. Trying to minimize cost anyway I can.

thanks007

[miata007]

I've just stopped by local Nissan to pick up the NGK spark (pfr6g-11). Got them to lower the price to $10/each instead of $14.00.

Have a question now. The box says to adjust to engine specification. I thougt I've read someone on this forum you don't have to make adjustment if you go OEM. Since I got mine from Nissan, does it make a difference?

Please help as I have never adjust a plug before and not sure by home much.

Thanks007

[qship96]

They should be gapped correctly right out of the box for your engine.....the last 2 digits of the spark plug part number{ 11 } is the preset gap, which is correct for the Q. Screw em in.

[3Q Jay]

we can agreee that HC is the misfire indicator for unburned fuel. since CO is within spec, the mixture is not overly rich.

certainly, over retarding the timing will have deleterious effects on all parameters.but there is a hypothesis that says unburned fuel particularly in the ring lands (yes i'm sure your 320k engine has perfectly clean ring lands, but his may not) can be an insidious source of HC. retarding the timing just a tad may allow that unburnt fuel to burn more completely, particularly if the engine is close to detonation point.

http://www.gordon-glasgow.org/emissions.asp

http://books.google.com/books?...num=7

http://icmc.kyungnam.ac.kr/sci...4.pdf

http://books.google.com/books?...num=5

[3Q Jay]

the -6g is a 'hotter' plug than the -5g.

both will fire, the -6g may be more prone to detonation than the 5g.

[maxnix]

6 is a "cooler" range for the sunbelt (FL,TX, AZ). OE on early G50.

Too bad you don't include your location in your profile!

11 refers to 1.1mm which is the correct gap. Civilians shouldn't alter this unless they have a professional tool that will keep the electrodes parallel.

[3Q Jay]

my error on having the range backward. Brian is correct.to 007, the -6 should be fine for so Cal, which i believe is your location.

with the -6 instead of the -5, you may need to keep the revs at 1800 while waiting in the queue for getting on the rollers.