Hello all,

Well I have just spent the better part of the last few days searching for a means to pass my local emissions test (live in Georgia). I have browsed countless forums and have not found a single write-up for helping a fellow RX-7 owner pass the test.

The metro-Atlanta emissions test consists only of:
gas cap pressure test
visual test to make sure something resembling a catalytic converter is there
~30 second idle test to make sure RPMs stay within limits (500-1000rpm)
15mph dynamometer with sniffer in ONE tailpipe ONLY for max 50 seconds
25mph dynamometer with sniffer in ONE tailpipe ONLY for max 25 seconds

They don't even pop the freaking hood...and if they do, then only to find a spot to put the rpm-gauge-checker-thingy for their computer...

For the following, in case different symbols/words are used on your local tests...
HC ppm --> Hydrocarbons parts-per-million
CO % --> Carbon Monoxide percentage
NOx ppm --> Nitric Oxide parts-per-million
RPM --> Revolutions per minute (duh)

By the way, here are the numbers from my first test, and yes, I made sure car was nice and hot first...drove interstate for about 20 minutes:

50/15 (15mph for 50 seconds)
HC ppm --> Allowed: 180 Reading: 401 FAILED
CO % --> Allowed: 1.01 Reading: 0.78 PASSED
NOx ppm --> Allowed: 1378 Reading: 833 PASSED
RPM --> Allowed: 3000 Reading: 1773 PASSED

25/25 (25mph for 25 seconds)
HC ppm --> Allowed: 174 Reading: 338 FAILED
CO % --> Allowed: 1.12 Reading: 0.64 PASSED
NOx ppm --> Allowed: 1258 Reading: 587 PASSED
RPM --> Allowed: 3000 Reading: 2036 PASSED

Well crap...unburned fuel...I always knew my RX-7 runs terribly rich (250 miles per tank city, but I have a lead-foot too). I just didn't expect by THAT MUCH! So I performed a tune up:

BUR6EQP Platinum City (Hot) Leading Spark Plugs
BUR8EQP Platinum City (Hot) Trailing Spark Plugs
Accell 300+ Ferro-Spiral 8.0mm Spark Plug Wires
HP1004 K&N Gold Performance Oil Filter
Castrol GTX Drive Hard 10W30 Oil Change
WIX Fuel Filter
WIX Air Filter (for stock air filter box)
Bosch 02 Sensor
16 oz. SeaFoam Clean-it-all stuff (poured into gas tank)

Naturally I left all the old parts in while I drove around until my full gas tank with the SeaFoam in it was just about almost empty. I then refilled with 87 octane, put in all the new parts, and proceeded to my second test, again making sure to do some interstate-speed driving for about 20-30 minutes. I left out the air filter for the test (but left the airbox in place) and also snatched off the Power Brake Booster hose on the passenger side firewall. Was hoping the additional air would help with burning excess fuel. Also, had the tester run higher RPMs this time:

50/15 (15mph for 50 seconds)
HC ppm --> Allowed: 180 Reading: 258 FAILED
CO % --> Allowed: 1.01 Reading: 1.13 FAILED
NOx ppm --> Allowed: 1378 Reading: 541 PASSED
RPM --> Allowed: 3000 Reading: 2930 PASSED

25/25 (25mph for 25 seconds)
HC ppm --> Allowed: 174 Reading: 175 FAILED
CO % --> Allowed: 1.12 Reading: 0.64 PASSED
NOx ppm --> Allowed: 1258 Reading: 462 PASSED
RPM --> Allowed: 3000 Reading: 2943 PASSED

As you can tell the Hydrocarbons definitely dropped tremendously. I failed the CO % this time around on the 15mph test, probably because of the vacuum hose I had snatched off from the power brake booster. Well crap...what next...I looked in all forums I could think of (or search for) and couldn't find anything real useful. So of course I figured the De-Natured Alcohol Trick should work. Today I let the tank run down to about 1/8th tank then added 1 gallon of Alcohol, then drove around about 20 miles (spirited driving, no pun intended) and then added 1 additional gallon of Alcohol, and of course drove straight to the testing station for my third test with all vacuum hoses attached and air filter in:

50/15 (15mph for 50 seconds)
HC ppm --> Allowed: 180 Reading: 275 FAILED
CO % --> Allowed: 1.01 Reading: 0.36 PASSED
NOx ppm --> Allowed: 1378 Reading: 762 PASSED
RPM --> Allowed: 3000 Reading: 1837 PASSED

25/25 (25mph for 25 seconds)
HC ppm --> Allowed: 174 Reading: 280 FAILED
CO % --> Allowed: 1.12 Reading: 0.41 PASSED
NOx ppm --> Allowed: 1258 Reading: 131 PASSED
RPM --> Allowed: 3000 Reading: 2041 PASSED

Well %@#$*& I was hoping this time it'd pass. In Georgia you get one free retest (within 30 days) per test paid for, so I was going to use my "free" retest right away (the test tech looked at me funny, LOL) I explained I'd like him to try his hardest to get the RPMs as close as possible to the limit by keeping the car in a lower gear. So he left the car in first gear for the 15mph test, but the %@#$*& couldn't keep it below 3000 RPMs in second gear for the 25 mph test and it reset the whole test twice because he couldn't do it right. He said come back tomorrow and he'd try it again.

Naturally, I'm a little pissed off. I was thinking the higher RPMs would definitely pass me along with the alcohol in the tank and all. The test tech guy said he didn't believe it would pass, since the cycle ran through all the time. Usually, if you have a "clean" vehicle, the test won't even run the full 50 seconds @ 15mph and maybe won't run the full 25 seconds @ 25mph either, because the sniffer tells the computer right away that the car is "good" and the only reason to use up all the time is if the sniffer isn't getting consistent readings and/or the car is borderline PASS or FAIL.

Just a few notes, before any of you start firing off a list of further questions:

The car is COMPLETELY STOCK, with the exception of the plug wires and I also have an aftermarket driveshaft with replaceable U-Joints. The motor has ~30,000 miles on it, and it's a "remanufactured" motor my friend's dad had installed by the dealership for the ungodly $4,300.00 (basically they just use a brand new bare block and water pump, then throw all the other old stuff back on) I of course only paid $2,500.00 for the car after he had all the work done. I've done my fair share of maintaning this gold-digger of a car. Routine oil changes between 2,500 and 3,000 miles. Spark plugs every 2-3 oil changes. Always run 87 octane. Make it a point to get the motor up to 6,500 RPMs at least a few times every time I drive (once it's warmed up, of course!) and tires, tires, tires...

IF ANYBODY HAS ANY SUGGESTIONS, PLEASE HELP!

I realize changing the Catalytic Converter out with a new & improved one will help, but I need a "quick fix" for right now and plus, the car running rich will just kill a new converter again!

*sigh*

 

It's a rotary; of course it runs rich. And you must not have searched this forum, because there is a wealth of information that I read and digested before I was able to pass emissions.

Now that that is settled, you might read through this thread.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/emission-testing-texas-style-465422/


I went down the same road, complete tune up, alcohol trick, goobering around with the airpump, completely diagnosed the emissions systems and guess what? I needed a new cat.

I replaced it myself with parts purchased and tools rented at Autozone. Spent about $140 including pipes clamps and the cat. I did it in about 4 hours one evening. I spent part of the next day replacing an exhaust stud. That took longer than the cat replacement.

A nice bonus is that most likely your cat has some damage and is restricting your exhaust flow. When you replace it, you will regain some lost performance and fuel economy.

Good luck!

 

Thanks for the reply! I'll look at the AutoZone catalytic converter and also see how long it would take to have a MagnaFlow shipped here. That or maybe I'll hijack the two high-flow cats off of a GMC Sierra Classic my buddy should still have at his house...

Any other suggestions, BESIDES a new converter???

Thanks in advance...

 

Look at the test results from each of my attempts. Yours look very similar. I bet if you use a new converter, you will pass easily. This assumes that your car is running correctly.

Good luck!

 

I'm going by the local AutoZone before they close to go look at the converter # 38734 (they have 3 in stock). The guy on the phone said it's "direct fit" or something and doesn't see why I need hardware... Of course not EVERY parts counter person is a bright one... I'll check it out in person... Have to do this fix quick, just like you had to...

Thanks!

BTW I don't have the precats anymore, so will I have to cut the pipe where the converter is welded to (on the front) and what about the back side...it bolts right to the beginning of the Y-Pipe on my car... Previous owner had exhaust replaced about 5 years ago and they must've scrapped it (the pre-cats) then... Some %@#$*& Midas-type Mufflers on the car now too... Sounds like @$$

 

I went and checked out the AutoZone converter. It's just a universal that you could get for $35 elsewhere. So I went and paid my vehicle tax and still have to pass emissions to get the tag sticker.

I did a little searching, and was about to buy this setup from PartsAmerica (Advance Auto Parts)

http://www.partsamerica.com/ProductD...pe=145&ptset=A

But didn't want to spend that much on something that's going to be removed in a few months anyways... Definitely a respected manufacturer, since they make the titanium exhaust on the Corvette Z06 and also the exhaust system for the M-Series BMWs, among other things. I almost did buy it though, because of the fact that the pipe extends all the way to the catalytic converter, where it BOLTS up, meaning you could later drop in a midpipe in place of the cat. It's like they were thinking ahead! LOL

Then I stumbled across this one, that I bought and should be here by Monday. Total cost came to just under $140 with shipping included from New Jersey to my home in Georgia. Manufacturer is "Eastern" and had never heard of them prior. Usually they sell you the same exact setup, except made by "CatCo" for around $175 plus shipping, but were out of stock.

http://www.autopartswarehouse.com/ca...2812&year=1988

I suggest calling the toll-free number, because if you use the online checkout, you'll more than likely get an e-mail back stating they will have to readjust the shipping costs, because it's an oversized package. Only *added*12 bucks to the shipping cost (online default was 20 bucks), no big deal. Hopefully everything will get here on time and be a simple bolt up. I'll post my findings and of course the new numbers from the smog test on Monday or Tuesday.

Thanks again for the help!

 

Any luck?