Bonez DP/Cat Failed CA Emissions Test
 

Our 1994 RX-7 has 72 K miles on it. The car, which was bone-stock, failed CA emissions testing, only 12 K miles after the 60 Kmile maintenance. I bought a Bonez downpipe and catalytic converter from RP and installed it last week, along with a new Bosch O2 sensor. The car failed again, but differently. I have summarized the test results in the table below.

CA Emissions Specs for 1994 RX-7 (Orange County), for year 2002:

Test ......RPM......%CO2.....%O2.....HC(ppm).....%CO ......NO(ppm)

15 mph..----........----..........---.......88...............0.52 .........1006
25 mph..----........----..........---.......53...............0.50 ..........866

Stock Test Results, 72173 miles 7/18/2002

15 mph..1841......15.0........0.4.......24........... ... 0.07...........118 PASS
25 mph..2874......15.0........0.0.......49........... ... 0.61*...........44 *FAIL

Bonez Downpipe/Cat, Bosch O2 Sensor, 72461 miles 8/05/2002

15 mph..1925......14.5........0.5.......59........... ... 0.02............37 PASS
25 mph..2921......14.7........0.0.......83*.......... ... 0.18.............7 *FAIL


All tests were run on the same machine by the same tester. Notice that although
the CO and NO measured values were greatly improved by the Bonez cat, the HC
numbers more than doubled at 15 mph and almost doubled at 25 mph, which failed
the car at 25 mph.

I have now spent over $1000 on parts. Ari has stated that the Bonez cat with downpipe should pass CA tailpipe testing, and I bought the kit with that understanding. We are now going to take the car to Irvine Mazda for troubleshooting; however, they do not guarantee that anything they do will result in passing smog (even on a stock car).

I would like to hear whether anyone thinks removal of the warm-up catalytic converter ("pre-cat") is responsible for the increased hydrocarbons, whether the Bosch O2 sensor might not be the correct type (it is a P/N 11027), or whether the problem might be due to some mistake I made when reassembling the car.

Because of a nut which was frozen to one of the studs mounting the pre-cat to the turbo outlet, I had to remove the rear turbo intake air pipe, the "air pipe and control valve assembly," which I believe some people call the "Y-tube," and all the associated vacuum hoses and inline air valves in the air intake system.

I put it all back together in accordance with the 1994 Mazda RX-7 Workshop
Manual, using new gaskets and O-ring where indicated. I also bought a
right-angle rubber hose from Mazda to replace one that had hardened into
"plastic," and a new downpipe-to-turbo outlet metal gasket. I have torque
wrenches, and torqued everything (where it was possible). The Bonez downpipe is
wrapped with a layer of Thermotec insulating wrap. Also, the car runs and idles very smoothly, and is quiet, but it seems down on power relative to performance before the work I did, which is a mystery to me.

This car is due for registration on September 12. I would appreciate as many suggestions as anyone can offer.

Thanks!

---- Bill

I know there will be some people who disagree with me on this, but I say that testing without the precat in place will affect your emissions testing results. I find it hard to believe that running the precat makes no difference. Here is my theory, your CO went down because you installed a new cat, but your HC went up because you aren't running the precat anymore. Test with the precat back on and the Bonez HF cat, along with some other smog test tips possibly.

Matt

I have passed with a DP with no problems. I dont think this is the cause. If you mean to tell me ARI cant find it then something is wrong here. I mean it is just a car people there are reasons why things dont pass emissions.Please check all the emission related items and you will find you answer or it will get you to the reason why.



-Rikki

Please post your testing conditions. With the pre-cat off, the car needs to be FULLY warmed up. As in a 1/2 hour of decent to hard driving to get the main cat fully warmed up. Also, 12k is a lot of miles for spark plugs. They should probably be changed. Also, when you put the Bonez hi-flow cat on, was the air pump hooked back up?

Rikki:

I am sure you are aware of this, but passing emissions in MD and passing emissions in CA are two different things. I know of multiple people who have not passed emissions in CA w/ a downpipe, putting the precat back on for the test can't hurt anything. Try running some denatured alcohol in the tank as well.

Matt

Yeah you could be right but I think it could be something else. Have you checked to see if you have the upgraded EGR gasket? It does make a difference.


--Rikki

Bill, emissions in CA are tricky. First are you running your airpump into your Bonez cat? Second, why did you change O2 sensors? I've known a few FD's that have passed smog without the Pre-Cat. I wouldn't think it's the reason you failed. Why did you change to a downpipe and Bonez CAT? Was it clear that the stock cat. was bad? Also, why did you change the 02 sensor?

Plugs make a huge difference in emissions. I keep a brand new set of BUR7EQP's just for SMOG testing. Make sure you run the 7's in the leading, the reason Mazda went with 7's versus 9's is for emissions. If I were you, I would put all of your stock equipment back on (as long as it is in working condition), and put new leading plugs in. Next I would clean out your purge tank (small black plastic tank below the intake elbow). Make sure the car is hot during testing. Go for a long drive before the test and when you pull into the station, leave the motor running all the way through the test. Post some more information for your car.

eric

I passed CA emissions (Test Only) on first try (July 01) with DP, STREETPORT, and Stock (30k+mi OLD) Cat. The test was done approx 1000 miles after my rebuild.

bad PLUGS will affect HC results - put in new ones just prior to the test also run the car HARD for 10 Min and do NOT let it cool down before the test - check for excessive fuel pressure at idle and/or Leaky injectors
:(

My brothers car with a PFS computer, dp, cat back and intake passed as a ZERO emmission vehicle in California.
I say put the stock cat back on and make sure the car is warmed up. After it passes put the bonez back on..only a 4 bolt 15 minute job..

I've passed emissions in California, Georgia, and Washington using the same Bonez main cat and no pre-cat (yeah, I move around a lot).

The increased HC is no surprise, ceteris paribus, given less restriction. The pre-cat is good for warm-up. No pre-cat = poor warm-up, but otherwise should not affect warm emissions results. Ideally, you want to get the cat as warms as possible. Cold start testers don't often allow you to do this- unless they're extremely busy and don’t care :)

Seems indicative of incomplete combustion or burning of oil. Things to check are plugs, plug wires, catch "can", and any other leaks. I'd seriously advise against using plugs with 12K miles. And make sure you have a nice pre-mix free tank of premium.

Gene

New plugs, oil change and fresh, full tank of gas. Nothing to loose. Don't forget anti-sieze on the plugs.

"If you hear hoofbeats, don't go looking for zebras".

Pretty much the same as the other guys
 

Yeah, your plugs are too old. You should have brand new plugs for testing. They will go bad in 8k mi. Don't go to Irvine Mazda for testing, besides they are over priced. The dealer will let your car sit for hours before touching it. You want to go to one of those drive through test only stations. It should not take longer than 15 before they test you and you car will still be hot. You can use 5W-30. I beleive that's the more environment friendly one. There is bottled stuff you can get at the auto store to put in your gas tank that claims to help pass and add some octane boost. Don't put premix oil in the tank though. I was told by my mechanic not to change the O2 sensor unless you get a code that it's bad. I don't know how well the Bosch compares to OEM. If fuel filter is older than 15k mi then change that to. If you can lift the car up, it would be alot easier to change the main cat then precat.

I agree totally. Good point. That purge tank holds alot of dirty gas fumes.

-Rikki

Thanks for all your replies. It seems there is disagreement about whether the pre-cat is needed after warm-up. To answer some questions: the O2 sensor was changed because it was the original with 72K miles on it and the car failed with it on, so I thought it would be a good idea. The oil is relatively fresh (500 miles), I am running CA 91 octane gas, and the car was as warm as it ever gets. No high-speed driving, but the car was rolled in almost immediately after a 3-mile run at street speeds. Water temp was normal. The tech runs the dyno at 15 mph first, with no fan blowing into the radiator, in order to warm up the engine, and both the stock and Bonez 15 mph tests passed. The 25 mph test failed both in stock form and Bonez form, but as you see, on different parameters. I believe there is nothing wrong with the cat or the O2 sensor.

I did install the secondary air path onto the Bonez cat per their instructions. I did not check to be sure the secondary air pump is working. Could that be a problem?

I didn't understand the comment about "the upgraded EGR gasket." I know what exhaust gas recirculation is, but why would a gasket make more or less smog??? Doesn't EGR affect mainly NO? And the car is fine there.

I did note some oil in the turbo output tube, but that would have been present in the stock configuration as well.

I will take the advice on new plugs (and wires? Sounds like Miata advice!) and give it another try. However, remember the stock car passed HC with these plugs and wires. I am sorta shocked that you folks think 12K miles on a set of plugs is a lot. Guess I'm spoiled by piston engines.

I sent basically a duplicate of my original post above to RP; hopefully they will have some input for me.

Thanks again for your time and thoughts, folks.

---- Bill

3 mi before testing?
 

I don't think that's enough to warm up the car. Yes the needle will say warm but it takes a good 10 min before it feels warm...or go one exit back and forth on the freeway.

Warm means at least 20 minutes of driving. If you go with new plug wires (and it IS time to get them at your mileage) get Jacobs, they are stout, well made and relatively inexpensive compared to some of the hyped stuff out there. Yep, the plugs really do burn out that fast. One of the downfalls of having 1.3 liter make 255 hp. Make sure you replace with plats - the non plats are worthless. You should be fine on the oil with only 500 miles. I now this sounds elementary, but is your air filter clean as well? It all adds up..........

Good luck and welcome to the wacky world of rotaries - where everything you've ever learned about boingers is about to be turned - around in circles!:D

(If all this does not work you could have some bad check valves or solenoids. The emissions system is a bear.......)

GoRacer & Ron,

Driving time was just about 20 minutes before test, stop & go. Air filter element has 9205 miles on it.

Are the OEM wires not good (a la Miata)? Who sells Jacobs wires?

If plugs/wires do not fix the emissions, it looks like the pre-cat will have to go back on. I don't want to do that, since this website says it is bad for reliability due to high underhood temps. But if that's what it takes to pass CA smog, that will have to happen.

Thanks again!

---- Bill

I'll bet its the plugs and/or wires. Everything else seems ok but make sure the airpump is engaging properly. Also, running alcohol is practically a guarenteed way to pass, you could probably pass with NO emissions equipment if you run a lot.

Did you check for error codes?
 

code 16 = bad EGR

I read all the above post very quickly, so I may be repeating, but from what I did see.... New plugs, for sure. Pre-cat, dont worry about it, I passed with a downpipe and the stock cat (70k miles). Clean air filter, good. Check to see air pump works & hooked up.... Your oxygen levels were low suggesting it was not working corectly. DO NOT go to a test only station unless you have to, they are alot more anal than the average gas station or small repair place that perform smog test as well as other business. Also, what gear was the tech guy in on the last run, make sure he doesnt rev the motor too much on the 25mph run so the airpump doesnt shut off (~3000rpm)

GoRacer,

With "TEN" and "GND" jumpered in the diagnostic connector and the ignition ON, the Check Engine light is on steadily; there is no flashing. Good or bad? Under normal running, it is off. On my Miata, with TEN and GND jumpered and ign ON, the Check Engine light is off when there is no problem. (??)

FD Racer,

Air pump is hooked up; Mazda manual says it should "be off above 3250 rpm." Note in my table that the 25 mph test on the stock version was run at 2874 rpm, and on the Bonez version was run at 2921 rpm. I just ran a test and the pump shuts off at about 3200 rpm on the tach, so I think it was running when both smog tests were done. That was a great tip, however, and I thank you!

Is there a "failure mode" of the rotary where one of the two spark plugs in a rotor chamber fails and the other one keeps working? How does that affect running? Even though the car runs smoothly, it seems down on power; could say a Leading plug be failing such that one rotor is running only on its Trailing plug? I would think that either being bad would affect emissions, but wouldn't it also cause both loss of power AND rough running?

I have to use a Test-Only smog station since I was so directed by my registration renewal form. Don't know why.

Anyway, I am getting new plugs and wires tomorrow. Once again, thanks for your responses.

---- Bill

We took the car into Irvine Mazda for new plugs and wires. The tech saw my smog results and looked at the car. He checked ignition operation and said the plugs and wires are fine. Basically he did not want to change plugs or wires and said it would do no good. He also said the Bonez cat converter is too small relative to the stock cat and that I should put the pre-cat back on the car. My inclination is to reinstall the pre-cat, leave the Bonez cat in place and have the car retested. From what some of you have said, that might work; others will disagree, I'm sure. After spending over $1000 so far, I'm not inclined to shell out another $1600 for a new, stock cat even if Ari will take back the Bonez stuff. Any more comments?

---- Bill

damn
 

Told ya not to go to Irvine Mazda. The is one in Laguna Hills. Did they charge you labor for the plug & wire replacement and not even replace them? :wtf:

If he had the F'n plugs out, he "SHOULD" have replaced them!!! The wires maybe not, but they are less than the F'n labor, damn! :bsflag:

It would have cost you less to pay to have the pre cat & main cat installed and them have the DP and Bonez installed after the test!:bss:

For that kind of money you could have went to Tri-Point. I beleive they do smog tests there, unless i'm mistaken. You could have also had a real mechanic figure out what's wrong.

GoRacer,

Maybe you misunderstood me. I haven't spent anything at Irvine Mazda yet. It would have been $280 for plugs and wires, but since the tech didn't install them, the cost of having him look at the car will be quite a bit lower. The $1000 I referred to was for the Bonez stuff, plus Mazda OEM gaskets & hoses, plus two smog tests so far. I don't know whether he pulled the plugs or not; I forgot to ask. When he said they were "fine" I assumed he had run the car on a scope or some sort of ignition tester.

---- Bill

Oh whoopsie :dunce: I appoligize to Irvine Mazda.

Call Tri-Point and ask if the do smog tests. For some reason I thought I rememberd reading they do. If your car fails, then they can figure out why.

I would replace the plugs anyhow.
Replace the fuel filter.
Get a bottle of Royal Purple fuel inhector cleaner
or Mazda fuel injector cleaner or Red Line.
Replace or clean air filter.
Get a bottle of octane boost or some race gas
Get a bottle of "smog test pass stuff"
(don't know anything about the alchohol the other guys mentioned)
Install the OEM cat yourslef (only temporary for the test)

You should get a 2nd test free when you fail the 1st. If not, go someplace else. So if you fail, install the pre-cat before the 2nd test.

If it still doesn't pass, then it sure wasn't the Bonez stuff.

Bill, I don't understand why you changed any of the equipment. Was it clear that the cat. or pre-cat. was bad? Or did the car fail in stock form? Here's what I would do:

1. put back stock cat (and precat if you so desire, but not necessary.).

2. New plugs (especially new BUR7EQP's in Leading)

3. Put stock O2 sensor back (Aftermarket O2's aren't as accurate)

4. Clean out black plastic purge tank

5. Run car hard on freeway for ~30 minutes or so.

6. Do not let car cool, keep motor running until test.

7. Make sure ALL electricals are off during test (turn off lights, fans, A/C, stereo, anything with electrical drain).

8. Also many forum members have run denatured alcohol in their tanks to help them pass, this is an option.

If you do these 8 things I'm pretty sure you'll pass with room to spare. Please post if there was something wrong with your stock equipment.

eric

I am confused. Wouldn't 9's have a bigger spark igniting more fuel? Not doubting you at all... Just curious as to why 7's and not 9's.

Please explain.

-- Eric

Thanks to GoRacer for setting me straight.

For others that don't know. :eek:

Specifications: BUR7EQP

B= 14mm Thread Diameter
U= Surface or Semi Surface Discharge Type R= Resistor Type Plug
7= Heat Rating *
E= 19mm Thread reach
Q= 4-Ground Electrodes (Firing End Construction)
P= Platinum *A spark plug's heat range has no relationship to the actual voltage
transferred though the spark plug, Rather, the heat range is a measure of the spark
plug's ability to remove heat from the combustion chamber. The heat range
measurement is determined by several factors; the length of the ceramic center
insulator nose and its' ability to absorb and transfer combustion heat, the material
composition of the insulator and center electrode material.

The insulator nose length is the distance from the firing tip of the insulator to the point
where insulator meets the metal shell. Since the insulator tip is the hottest part of the
spark plug, the tip temperature is a primary factor in pre-ignition and fouling. Whether
the spark plugs are fitted in a lawnmower, boat, or a race car, the spark plug tip
temperature must remain between 850-1500 degrees F. If the tip temperature is lower
than 850 degrees F the insulator area surrounding the center electrode will not be hot
enough to burn off carbon and combustion chamber deposits. These accumulated
deposits can result in spark plug fouling leading to misfire. If the tip temperature is
higher than 1500 degrees F the spark plug will overheat which may cause the ceramic
around the center electrode to blister and the electrodes to melt. This may lead to
pre-ignition /detonation and expensive engine damage.

The firing end appearance also depends on the spark plug tip temperature. There are
three basic diagnostic criteria for spark plugs: good, fouled and overheated. The
borderline between the fouling and optimum operating regions is called the spark plug
self-cleaning temperature. The temperature at this point is where the accumulated
carbon and combustion deposits are burned off.

Bearing in mind that the insulator nose length is a determining factor in the heat range
of a spark plug, the longer the insulator nose, the less heat is absorbed, and the
further the heat must travel into the cylinder head (rotor housings) water journals. This
means the plug has a higher internal temperature, and is said to be a hot plug. A hot
spark plug maintains a higher internal operating temperature to burn off oil and carbon
deposits, and has no relationship to spark quality or intensity.

Conversely, a cold spark plug has a shorter insulator nose and absorbs more
combustion chamber heat. This heat travels a shorter distance, and allows the plug to
operate at a lower internal temperature. A colder heat range can be necessary when
the engine is modified for performance, subjected to heavy loads, or is run at high
rpms for a significant period of time. The colder type removes heat more quickly, and
will reduce the chance of pre-ignition/detonation and burn-out of the firing end. (Engine
temperature can affect the spark plug's operating temperature, but not the spark plugs
heat range).

The NGK heat range is from Hot (2) to Cold (10).

Reprinted from the NGK Product Catalog.

GoRacer,

No free retests at Test-Only stations. $29.75 if you fail, $38 if you pass. Every time. (The $8.25 is a DMV document fee only if the car passes.) I'll try to get hold of Tri-Point, thanks!

hapa,

Changed parts because existing parts failed smog test, and I would like to register the car for next year! Yes, the car was in stock form, as I wrote. It was and is not clear what was bad, and will not be clear until it passes. (However, my Miata had about 70K miles on its cat and failed; I replaced it and it passed with flying colors.) Also notice the measured emissions in my original post: Great improvement in CO (which had failed) and NO with the new cat, new O2 sensor, and no precat. So that part of the change worked.

Problem is that at 25 mph the HC, which barely passed on the stock car, increased by 69% with the new cat/DP.

1) I am NOT putting back the stock cat.
2) I was having plugs changed, but the Irvine tech said they are fine.
3) I think the new Bosch 11027 O2 sensor is fine; I use the Bosch sensor on the Miata and it is fine there too.
4) thru 7) I will try all this stuff (if I can find the purge tank, I will clean it).
8) How about a bottle of Techron in the 91-octane fuel? Don't know squat about adding alcohol, and it isn't really legitimate to do that, I think.

Yeah, there was something wrong with the stock equipment. IMHO, the cat wore out. Maybe the O2 sensor, too. And maybe all you folks are right and the Mazda tech is wrong; maybe the plugs really are not "fine."

Maybe, eventually, I'll find the magic combination.

I do appreciate your replies.

---- Bill

Boy, this will be interesting when it's my time for smog renewal . I also have the Bonez main CAT, M2 downpipe, M2 SMIC, M2 Intake, and the Bosch O2 sensor. I have previously not had a problem with passing, but that was before the addition of the SMIC, Bonez main CAT, and Bosch O2 sensor. We shall see. For sure, I will have a fully warmed engine!!;)

Just in case you run out of time
 

You can send your payment in without the proof of insurance and proof of smog. As long as you pay your renewal fees, you can "not" be cited (no ticket). That does not mean you can't get pulled over because you don't get the stickers. It just means when the Chipy runs your plates it will show you have paid and he can not cite you a ticket for over due registration.

having a high number on the HC means u have some leftover hydrocarons wich is your unburnt fuel, your car is runnig too rich, get new plugs if u already havent and check your air filter. :) goodluck

It seems like your car should pass, but definitely clear up the catch can or block it off. One easy way to see if you car will pass without going to a test only center is to get a pre test. Lots have said to have the car fully warmed up and i repeat it should be really really hot, agressive driving helps. A bottle of Redline fuel injection cleaner wont hurt neither, just make sure that stuff is gone when you test you car. Have the tech probe your car at idle, if it doesnt pass, have him rev the car and wat the readings, if slowly gets better then it should be fine. I really think its jsut that the car is not hot enough. If you car idles smoothly thats a good sign also. The reason that you were selected to go to a test only center is because its random, i think 30% of the people have to go to test only centers, thats why they have so many in So Cal, we only have like 5 in San Francisco. My cousin owns one somewhere close to Disney Land and thats what he told me. They are thinking about having that test only shit up in San Francisco but i hope it doesnt happen. And make sure when you do the real test that all you accessories are off, even the dome light and that the tech doesnt go into boost.

I too am having problems with MA dyno emissions tests. I failed with stock cat and dp with a PFC. I then bought a used 1K mile bonez (looked like new) and failed again. I then got someone that owns a four gas analyzer (he helped set up MA emissions program) to tune my PFC w/datalogit in the map regions the test uses. He had to do this with no cats since the probes would be affected by them. I got the car back, put the bonez back on and it still failed! I then called Tri-Point and talked to someone about my high HC numbers. He said that since my CO2 levels where so high it appeared my cat was not working. I have verified my airpump is getting air to the cat. I have been told that my bonez cat is probably carboned up from being used with a rich running ECU.

I just got a new TriPoint cat and will try again once I get time with new plugs (again), oil and a very hot car.
I do agree that the Bonez is puny and wonder if it is even a three way. The TriPoint cat is much larger than the bonez, almost as large as the stock cat but much lighter, claimed to be freer flowing and is much cheaper than an OEM.

If this doesn't work I may just turn the &@#% car into a trailer queen...

grampa et al,

Since my last post I realized that the "check valve (split air)" is part of the original cat and when the Bonez is installed, the valve is lost. So since my O2 readings were 0.0%, I cut the valve off the old stock cat and checked it to see it was working (it was), then I spliced it into the secondary air pipe into the Bonez and had my car retested. Sure enough, the O2 came up to 0.6%, but the HC was unaffected!! Which means to me that the O2 injection into the Bonez cat bypassed the conversion process and just went flying out the tailpipe. I don't know what the Bonez cat looks like regarding air injection, but I expected the HCs to go down with more air available.

Last night I installed new spark plugs (against the Irvine Mazda tech's advice, but I need to know). The old plugs with 16K miles on them all looked the same... shades of tan on about half the ground land with the other half black with carbon. This morning I will have the car tested once again. This is the last test with the Bonez cat. If it fails, I am buying a new stock cat but leaving the Bonez DP installed.

Full power is back; I had failed to tighten one of the large hose clamps at the output of the "air pipe/air control valve..." duh. (The Irvine tech found that.)

---- Bill

I wish I could get mine retested with the Bonez replaced by the new Tri-Point cat before you do this. The Mazda main cat is $$$. The Tri-Point is ~$450.00, they even have a high flow precat listed but were out of stock the last I called.
I do plan to get the test done late next week with the Tri-Point (if I get time).

grampa,

How do I get hold of Tri-Point? Thanks!

---- Bill

http://www.tripointengineering.com/

Good luck

SH*T I am so pissed at myself for not reading this post earlier. I went to smog my car today at a Test only station today. The first one I went to made me wait 2 hours because he was busy then tell me his machine can't pick up the rpm's in a rotary so he sent me to another place up the street. Well I wait another 1 1/2 hours and I don't pass. I wanted to run the car when it was hot but I only live like a mile from the test station so I guess I never got the cat hot enought. Also I have 3/4 full tank of PREMIXED gas, which I know found out is a bad thing to have when smoging a car. Can the heat do anything also in affecting the outcome of a smog test. 'Cuse it got up to 103 today where I live at and I they tested it a like 1:30pm.
Well heres my emissions test results.

co2 O2 HC CO NO
test rpm max meas Max meas
15 mph 2918 14 0.2 88 34 .52 .49 161 Pass

25 mph 2957 14 0.0 53 60* .50 .86* 119 FAIL

As you can see I barely passed the 15 mph test, but failed the 25 mph misserably. Do you guys think it is my cat. I am going to change the plugs, I am due for and oil change, check the air filter, change the fuel filter(have it just havent' put in on), and I have to wait till I waste all that premixed gas in the tank.
One more thing, how much denatured alcohol due u mix the gas with?

Sorry that the numbers are all moved around, I posted it right but I guess the got all mixed up.

grampa,

Thanks for the link!

kundo,

Is your car stock? I just returned from my fourth failed test, HC still bad at 25 mph (94 ppm). My car failed stock not on HC but CO (.61%), so I bought a Bonez DP and converter, and new O2 sensor. Installed and retested. Stock, my HC was 49 (passed), but with the new converter/DP/O2 sensor, HC went UP to 83. However, CO came down to 0.18, and NO readings also dropped a lot. Since that retest I refitted the check valve from the old stock cat (Bonez doesn't have one) and changed plugs. Retested again. CO and NO still better (passed with more margin) but HC up again at 25 mph to 94 ppm. Irvine Mazda tech says the Bonez cat is too small. Since reinstalling the check valve, I noticed O2 went up from 0.0% to 0.6%. Well, the secondary air is flowing better into the Bonez cat, OK, but it should be burning off the HC and instead is just flowing out the tailpipe.

My wife has had enough of this fooling around (it's her car), so we ordered a new cat converter from Mazda today ($1281 with gaskets and tax). I am going to leave the Bonez DP on since I want to be rid of the pre-cat, but if it fails again... no, think positive. Hopefully Ari will refund my money for the Bonez cat.

---- Bill

Please update when you pass
 

Damn, and I was upset when I burned two $250 Random Cat's on my Honda (bad distributor).:eek:

I thought Irvine Mazda was very expensive, but if they are helping you then it's worth it.

You need to make sure that is not something causing your engine to burn up the cats. I thought I had a bad Cat on my Honda but it was a bad distributor that wasn't burning the fuel and the Cat glowed red like a bbq charcoal.

I would like to see the results on the Tri-Point Cat'! My buddy has the Tri-Point pre-cat and they cost $700.00 ouch, but he has an Auto.

GoRacer,

I plan on posting whenever the car passes. BTW I made a typing error on the price of the Mazda converter; after tax it was 1382.80, not $1281.

---- Bill

a comment and a question:

comment: i think the check valve is simply a one way valve which prevents exhaust gases from backing up into the smog pump. if it is malfunctioning and preventing airflow into the cat it would be a problem on measured emissions, however, if left off, it shouldn't change measured emission. please correct me if i'm wrong on this.

question: for those of you who have used alcohol in your tank, exactly what kind and where did you get it. is it ethanol, methanol, or something else......does home depot have it (solvent)??? are the bottles of "guaranteed smog test passing stuff" that you get at pep boys alcohol, or some other stuff.

tia
fabian

FWIW, the first smog test on this car was in 1996 at 19657 miles. It failed with 550 ppm HC and 3% CO. This made the car a "gross polluter" and forced retest at a "test only" station. Car was stock, never touched by us after buying it new in Sept.'94. There was a pinched solenoid wire (open circuit) controlling air bypass valve, a vacuum hose misconnected, another vacuum hose deteriorated and leaking, and "other various leaks." Retest passed, but I have no data.

In 1998, at 38070 miles, the car passed with measured HC levels of 2 ppm @ 15 mph, and 8 ppm @ 25 mph. Interestingly enough, in 1998 the HC limits were 125 ppm @ 15 mph, and 75 ppm @ 25 mph.

In 2000, at 57431 miles, the car passed with measured HC of 6 ppm @ 15 mph and 11 ppm @ 25 mph. The requirements in 2000 were still 125/75. This means the CA requirements on max HC have tightened by 30% @ both 15 mph and 25 mph between 2000 and 2002! Is the RX-7 supposed to get better with age?

Fabian,

You are correct about what the check valve does. But the exhaust pressure in the cat is not constant; it is pulsing high with each exhaust port opening of the rotor chamber, and the peak pulses may be higher than the air pump pressure (spec'd at > 0.7 psi) although the average pressure is probably lower. So if the exhaust backs up into the clean air supply on peaks, the net volume of clean air going into the cat has to be lower if the check valve is not in place. I think my test results show that is true; before putting the check valve back in, O2 output at the tailpipe was 0.0%, and after reinstalling it, O2 went up to 0.6%. Also... would a car manufacturer put in a valve that was not needed? I don't think so!

---- Bill

$1380 for a CAT? Damn Bill your hardcore, I don't have the stomach to pay that much for a cat. Maybe you could try Brian at Mazdaformance.com , He give's excellent prices on OEM parts. Sorry your having so many smog issues, I can't think of anything else to recommend to you. Good luck with your new cat, and let us know the results.

eric

wstrohm
Yeah my car is fully stock right now. I bought a Downpipe yesterday and in my haste I went to smog the car today and I never checked it or thought about it not passing smog. I wanted to put my DP tommorow but since I didn't pass now I have to give the car a good tune up and see what happens. The good part is my tags don't expire till late October.

kundo,

I don't know how much you want to fool around getting to be an expert about what affects emissions, but if I were starting over with my stock system that just failed, the first thing I would do (given that my car was on its original O2 sensor at 72K miles) is install a new O2 sensor and change the plugs. I would then take the car to a certified smog test/repair station, and get a pretest. If it failed, I would leave the car, and have them tell me what needed to be replaced. They have the dyno, which I don't. There are so many things that play into the tailpipe emissions, anything else is an expensive DIY project, as I have found out. Replacing the pre-cat with a DP will not help emissions, but I have been told it will not hurt emissions if the car is fully warmed up. I would suggest using Thermotec insulation on the DP to prevent much cooling of the exhaust gas entering the converter.

My next report here will be after I have the Bonez DP mated with a new stock Mazda cat.

---- Bill

wstrohm,

Please cancel thad order with Mazda ASAP.
Don't waste money that way.

I can let you borrow my stock cat.
I just passed emissions with flying colors.

I have:
M2 Exhaust, DP, Greddy SMIC, M2 Intake and M2 ECU.

All were installed at the time of the test.
Therefore, you know my Stock Cat is good.
I can send you a copy of my test results as proof.

Since you were previously happy with your stock cat just put it back on after the test and make me a good deal on that Bonez cat.
I was waiting untill after smog to install a High Flow cat.

Naturally, I want to keep my stock cat for future smog tests or I would just trade you for the Bonez.

If you really want a new stock cat (I don't see why) at least let me get it for you with my Mazda Comp discount.

I highly recommend you try my stock cat first since it is proven to be good.

Please PM me.
I just PM'd you as well.

Lunar7,

I understand and appreciate your offer, but I do not want to set up my car to pass smog, get the car tested, and then revert to a setup that would not pass smog. I admit I used to think that way, but no more. Maybe I'm getting old.

You have confirmed my faith that I can keep the Bonez DP and pass CA emissions with a stock cat; thanks!

If my retest with the new stock cat DOES pass, I will return the Bonez cat to Ari for a full refund. I wasn't worried that the CARB has not "approved" it as long as it works, but if it doesn't, that's a different story. I think it's false advertising to say an RX-7 will pass CA emissions with the Bonez cat, if it will not.

---- Bill