Hey everyone,

I recently took my '88 FC GXL for a smog test. I swapped the old exhaust system back on, drove it until it reached idle, and took the test on a hot day, but it still failed due to high HC and CO% levels. Could I have failed due to premixing(currently running royal purple 2-stroke oil)? I'm considering replacing the catalytic converter and oxygen sensor. The tester suggested I go to a tune-up with the cat and o2 sensor replaced, but I'm pretty sure that I don't need one. Any advice or tips on how to get it to pass? I currently have a retest for free in 30 days; any help would be appreciated.

 

If you have an intact air pump, verify it's working with the ACV, solenoids(if I am not mistaken), etc. Section 4 in the FSM.

Burn a tank of gas with known good injector cleaner and drive it hard for at least some of the middle to end of the tank. Then take out the plugs and replace with new ones before the test.

The O2 sensor only works in 5th gear if I am not mistaken.

Verify the premix levels and run it as low as recommended in a small tank of fuel before the test. Then fill up and mix heaver after the test.

After that, you are at replacing the cat.

You are double the limit, most likely it's your air pump and mix situation, if the cat is good. The others will not move the needle nearly as far.

Any other takers here? I am sure that I am missing something here.

 

According to the previous owner, the car was largely stock except for aftermarket suspension upgrades and custom rims(I am slightly worried that the PO lied to me because there are some hanging wires and space in the engine bay). According to my mechanic, there were some modifications made to the O2 sensor port when the previous owner changed to the full RacingBeating Exhaust System(Headers, Presilencer, Catbacks, No Catalytic Converter). I swapped it back to the OEM for the smog test.

I talked to a rotary shop called Sake Bomb Garage since I live in the Bay Area and they suggested a Tune-Up for sparkplugs, the plug wires, and any vacuum leaks, quoting me for about $500-1000. I reached out to a buddy of mine who also told me to probably replace my vacuum lines. I'm unsure whether this could be a DIY for the Tune-Up or if I need to bring it into a shop. I can wrench on cars, but I'd say my automotive level is pretty basic from sparkplug changes to changing brakes. I was hoping to learn more about my car and understand it better in the future, but I'm unsure as to if this situation is pretty bad and if I should give up on my dream car. I am pretty busy with school now so I'm considering just non-oping and selling and biting the bullet. I knew coming into this would eat money, but I guess I only found out the hard way.

Quick Question:

For the injector cleaner, do I just put it into my tank after running it empty and filling it with gas? Also am I able to verify if my catalytic converter has gone bad using a pressure gauge on an FC?

Here are a few photos of the engine bay for reference and another reference to the test:

 

More photos:

 

what does took the test on a hot day mean? the car needs to be hot, not the weather.

my check list is to verify, or set the, timing, TPS and idle mixture, then you can reach under the car to the ACV vent and verify that the ACV is working (it is your numbers are pretty good)
then it should pass.

if it doesn't pass the o2 sensor is easy and cheap, and after that i've never had one fail, lol

 

The car was hot and it was taken in a hot day. I don't know if that affects anything, I just wrote it down to note.

 

I see one vacuum port on the intake manifold not connected so that's messing with your mixture. Did you put the ACV on yourself and did you have the ~1" diameter check valve?
Also, make sure the plug wires are correctly attached and sparking. The inline tester is great for that.

 

The state the car is in now is basically how I bought the car. I haven't had time to check the ACV, but I should be able to tomorrow morning. I'm planning on just doing a tune-up, servicing the car(oil change), vacuum leak checks, cat check, and any other parts you guys suggest, but I also believe premixing is what led me to have really high CO and HC levels because I have a working OMP(according to the Previous Owner) and I usually eyeball 1 oz to a gallon on fill-ups.

I assuming I should be able to find the ACV using the FSM or does anyone know the location?

 

For the vacuum port are you talking about this?

 

this guy, does the MAP/Boost sensor vacuum line go here?

 

[QUOTE=satoru;12613713 I have a working OMP(according to the Previous Owner) and I usually eyeball 1 oz to a gallon on fill-ups.
[/QUOTE]

I don't know how it effects smog but from everything I've read on here that's too much oil if you have a working OMP.1oz per gallon is roughly 125:1 which is about right with no OMP. I heard 400:1 is what popple run with a working OMP. If your OMP work you could run no premix in the tank of gas you use for your smog test.

Here is a premix calculator.
Premix Calculator

 

Now that I have time to look at these pictures on a desktop, I thought, "this looks like my car". And pinstripes.... seriously though, it looks pretty stock. The missing hose is the pressure sensor as far as I can tell. The first picture in the "more pictures" section shows it pretty clearly. If you get that in there, it could be most of the problems combined with the premix.

Fuel injector cleaner gets used per the instructions on the bottle. As far as a test for a cat.... I am not sure besides a smell of fuel, a smog test and a loss of power at the acceleration pedal. Sometimes they will clog and bog down the engine.

Don't give up on your dreams. The nice people in the thread here will guide you along. I will duck out now unless you get ghosted. You are in good hands with the others. Best wishes!!

 

Hey Jeff,

Thanks for the advice. It motivates and is inspirational to see all the senior members with their knowledge and willingness to help out the new guys. Thinking about just following some of the advice and doing it myself even though I'm busy. I took basic automotive and my friend who's a SAAB tech said I could prob do it and wouldn't have to bring it to a rotary shop. I'll give it one more go and hopefully get her to pass! Will check-in whether it fails or passes.

 

Gotcha. I've had people tell me that premixing even with the OMP doesn't help, but this is definitely useful. Will take a look at this.

 

I am putting in my third engine on my 88 GXL.

Original engine lost an apex seal, I was two quarts low on oil at the time! 75k miles, hindsight is 20/20!
Atkins street port engine spun a bearing after another 75k miles, I kept a close watch on my oil level.
Now I plan on using synthetic 10w40 after break-in with conventional 10w40 oil for 600 miles.
Along with a proper amount of pre-mix per gallon of fuel with a functional OMP.

I am willing to change out my spark plugs every year if I can prevent compression loss and lack of oil lubrication from causing premature engine failure!

What do you think? Your comments will be deeply appreciated!

 

Smog tech of 15 years here. Looking at your gas readings, you're running too rich. High hc, low nox, CO way off and co2 reading rich, o2 looks good. You don't have vacuum leaks. Probably exhaust is good too. O2 sensor could be skewed, mixture screw could be set wrong. Without standing in front of the car, that's as much as I can tell you. Pm me with any questions

 

Airpump and ACV need to work or it will not pass. Airpump air should be flowing to the exhaust port through the port air valve in the ACV, and catalytic converter needs to be in working order.

Basically the airpump goes into the ACV. The ACV either directs it to the exhaust port (before the O2 sensor), or into the cat. In most cases you want it in the exhaust port.

post #1 and post #17 (thread was written for an FD but it's mostly the same on an FC) "Why is this engine so damn complicated??" Part 2: Emissions controls - RX7Club.com - Mazda RX7 Forum

 

Any updates?

 

premix is bad for cats and will slowly reduce its ability to pass emissions. you are a little fat on the fuel, a quick and dirty method to correct this without doing any other major work in diagnosing is to water down your fuel with denatured alcohol so you can figure out the real issues later. as far as i recall the mixture trim pot only affects low RPM and idle.

 

I wonder if tightening up the AFM a few notches would close the door slightly more, making engine see less air flow, and not adding as much fuel to get to a leaner condition

Having High CO makes sense for richness, so the more it can be leaned out, can bring that down along with the HC, with not much change to NOx


1.0 lambda is 14.7:1 AFR

 

Hopefully all this will be a non-issue in the near future. A few weeks ago, "Leno's Law" (SB 712) was passed out of the California Senate Transportation Committee.The law aims to exempt classic cars, those 35 model years or older, from smog check requirements in California.The bill is headed to the Senate Appropriations Committee next, for further consideration.

 

kind of silly to name it that, it is merely a continuation of the stalled rolling emissions exemption that it took a person with stature(read as a person with money who likes to pay others for fancy cars to show off in their warehouse of a garage, yeah he wrenches, but a lot less than people think he does) to bring back to life. we name laws after dead children too, those naming conventions i respect a little more though.

the fact there is a lot fewer 80s cars still resurrectable in california is why it had less resistance to passing. folks who managed to keep their car passing emissions for the last 30+ years both have my sympathy and my respect.

 

I failed twice but managed to pass on the third attempt! I got help from a guy in the NorCal RX7 Group and found the MAP sensor unplugged. I plugged some of the exhaust leaks(albeit, it still sounds and smells like it's leaking)with JB weld and just did a tune-up. It took me a long time because of some other issues(like the clutch master cylinder going bad), but I was able to get her on the road after 5 months, haha. I'm just glad it passed. This past half of the year has been a rollercoaster because this is my first time working on cars and manual car, but it's been a great experience and I'm loving every second of it.

 

Congrats! Me too! Took me over 4 months and two failing tests. My problem was a plugged fuel return line jacking up the fuel pressure and HC and CO. I’ve never been so happy passing smog and getting registration/plate.