j9fd3s

iTrader: (3)

yes. back in the old days, we played around with an 84 i had on a gas analyser.

when you set the mixture so the engine ran the best, it barely failed. leaning it out make it worse. richening it up made it pass.

if you were to put an o2 sensor right before the cat, on a stock, functioning car, you would see that the mixture is about 16:1 (it'll vary a little). this is due to the air pump supplying air into the exhaust ports. the cat works best with a mixture closer to 14.7, so running the engine a little richer than normal lowers the smog numbers.

running the engine lean creates misfires, which is like a full chamber of unburned fuel going into the exhaust. misfires will basically spike the hc's way up.

the evap test is pretty simple, they just pull the line from the charcoal cannister to the gas tank and see if it holds vacuum. it actually should, theres not many places for it to leak.

i'm in CA too, ive been smogging these things since like 1993, they all pass leagally too.

bliffle

The PnP ACV I have is from a CA PnP so I'm guessing it's CA rather than federal.

Those ACVs cost about $400 from mazdatrix! I'm guessing that just the diaphragm (are there 2?) ruptures, or something. What else can go wrong with it?

I wish I could pinpoint the problem a little better. Right now the possibilities seem to be:

1-leaky carb
2-bad ACV
3-burned out cat
4-bad rubber tube under the carb

I need a way to eliminate some of those so I don't go replacing unnecessary stuff.

I put a new Bonerz in my 85 about 5 years ago, and I think they last long as well as flow well. Maybe I should do the same on the 83, just on General Principles.

Carb rebuild kits are about $50-60 but maybe I need floats, too. I suppose I have to remove the carb to rebuild it, which is a hassle. Do I have to remove it or can it be o'hauled from the top?

This is the 'smogtips' analysis I paid $20 for:


SMOGSMART VIR REPORT - 1983 MAZDA RX-7 1.1 LITER

SmogSmart VIR Report #154366



Your vehicle's emissions results: High CO at 15/25mph. High HC at 15/25mph. Possible rich fuel mixture. Vehicle failed CO with very high numbers. This condition is called a "rich fuel mixture". The diagnosis for this failure should include close inspection of your vehicle's fuel management and control systems, with heavy emphasis on the carburetor.



What causes a Rich Misfire, and how does that create high CO: CO stands for Carbon Monoxide. It is a by-product of incomplete combustion, more then often related to the presentation of too much fuel to the combustion chambers. The spark created at the sparkplug can only burn a small amount of fuel, the fuel it cannot burn is sent out the tailpipe and will normally contain high levels of partially burned fuel(CO) and un-burned fuel(HC). Let's look at two primary causes for excessive fuel presentation to the combustion chambers.



Fuel distribution in your vehicle’s engine is primarily controlled by the carburetor. If any component within the carburetor is defective air/fuel ratio can be disrupted and result in incomplete combustion. The presentation of too much fuel will produce high CO emissions. The presentation of not enough fuel will produce low CO emissions. If your engine's carburetor is defective you have two options. You can ask a local smog tech to try and adjust the carburetor (if possible) or you can ask to have the carburetor rebuilt (a little more expensive but the performance increase will definitely be noticeable).



On computer controlled engines, fuel distribution is also controlled by the vehicle's computer system (ECU). The engine has several emissions sensors such as the, TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature Sensor) and the MAP or MAS (Vacuum/Pressure Sensor) which send vital engine information to the computer, and which the computer uses to determine proper air/fuel ratio.

Your vehicle's engine is NOT computer contorlled. Your vehicle does not rely on any electronics for fuel/air control... getting it to pass the smog test will be a simple matter of adjusting the carb or if need be getting it rebuilt.



Final Comment: There will be a few steps involved in finding out the root cause for your vehicle's failure/s. The emissions system/s responsible for causing high CO & HC will have to be individually diagnosed, and step-by-step eliminated as faults. Please Remember: California law only allows State Certified Smog Repair stations to conduct smog inspections and smog repairs on vehicles being driven in California. We highly recommend you search our database of SmogTips State Certified Smog Repairs stations. SmogTips Certified Stations are pre-screened for quality repairs, fast friendly service, and reasonable prices.



SMOGTIPS SMOGSMART VIR REPORTS - Save Money. Smog Smart. SmogTips.com - "California's Leading Smog Check Support Group" - 1-877-SMOG-TIPS

bliffle

Aha! So maybe I should richen it a little and retest!

I can probably check that cannister hose with an airpump.

boyee

iTrader: (3)

Well richening it up makes sense. I would have leaned the fuel out like you did but now I know it might have a reverse effect.

Anyways, sounds like you have a good start at where to look to troubleshoot your car to pass smog. Hope it passes on its next test! Make sure to drive it pretty hard for a good 20-30 minutes and get the engine real hot!

bliffle

I'm going to try getting someone like Ivan to tune it before I start pulling parts out. If I do that then it's the carb first (which shows no sign of ovehaul otherwise), then the ACV, the the cat,....

boyee

iTrader: (3)

If you still have your stock heat shields underneath I'll be crossing my fingers that you won't need to cut some of the hangers because the tiny bolts don't budge even with PB Blaster and get rounded lol.

j9fd3s

iTrader: (3)

if the car hasnt sat around long enough for fuel to turn solid (3-4+ years) then its not the carb.

ACV is a common failure, really easy to check. theres a big hose from the side of the acv to the side of the air cleaner, if there is air coming out of that at idle, ACV isnt working right.

bliffle

The ACV seems to be working right.

I'm starting to think that replacing the cat might be the best. Even if it isn't the actual problem it should cleanup the HC.

I can't believe it's the carb, since it has always. like now, run smoothly.

boyee

iTrader: (3)

Since you were just a tad off from passing a new cat should do your car well! They do go bad over time and since the rest of your car is running smoothly hopefully your car will be passing the next bunch of smog tests!

bliffle

The cat on the 83 was put in 4 years ago, but it was only $200 installed, so it may have been just a cheap aftermarket unit.

DivinDriver

iTrader: (15)

Sure wish I knew how this turned out: Bliffle, did you ever pass?

boyee

iTrader: (3)

If he put a new catalytic converter, he should have since he was just barely producing a little more over the limit.

petex

HCs are high when ACV is dumping out air from air pump

ACV directs air 3 directions. port air, split air (cat) and relieve (dump)

the problem can be vacuum or switching or relieve solenoids on rats nest.


so a simple test. remove the dump hose from ACV. rev the engine to 3-4k rpm. there should be no air coming out.

kashe

I am having the same problem air is being dumped into my air cleaner. Can anyone till me which solenoid controls this? Ihave a another on to check it with .I will also put on a different acv and see if that helps. Cal smog is ruff

DivinDriver

iTrader: (15)

Wear points on the ACV are diaphragm rupture, port clogging, spring failure, and wear on the bypass valve bushing (round valve on the spring) where the shaft goes thru it. The hole wears larger, starts leaking progressively larger amounts of air, which prevents it from opening right, and from building enough pressure into the injection circuit.

It's useful to re-grease that shaft on occasion, even though it's not a maintenance item. Once the disk wears away sufficiently, the valve's done. No replacement available, as its retainer is swaged in.

thunkrd

iTrader: (1)

does this only apply to 12a?

boyee

iTrader: (3)

all rx-7s had air control valves if that's what youre asking

DivinDriver

iTrader: (15)

My info was specific to the SA ACV's, though the design concepts appear similar on later units.

thunkrd

iTrader: (1)

i can't wait till our cars don't have to be smogged

boyee

iTrader: (3)

i thought in cali they changed the law that only pre-1975 cars are smog exempt so our cars will have to be smogged forever

DivinDriver

iTrader: (15)

They did. Thank you, Arnold "my ***** are in Maria's eco-friendly recycled purse" Schwartzentraitor.

MattG

iTrader: (2)

Man I hate to hear abot this smog mess. It seems like such a pain for a car that is almost 25 years old. The technology was not top of the line back then, so I dont see how they think all of a sudden its just going to conform to todays standards.

DivinDriver

iTrader: (15)

They are not particularly interested in it complying at all; the government would much rather see us all driving brand-new cars, partly because they are cleaner, and partly because that generates the maximum in tax revenue for them, and makes their union taskmasters happy.

The fact that it is our money, our cars, and our state, does not concern them overmuch. They are interested only in the "greater good..." greater, for them, that is.

my1st7

Could you explain your post starting out " wear points on the acv ...." ? It was way above my limited knowledge but sounded relevent to my problem. My cat on my FB is shot and so was my Shutter valve. Replaced shutter, haven't tested the acv at the air cleaner yet, Boyee is helping me.

j9fd3s

iTrader: (3)

it did pass. it needed an intake gasket. my friend who did the work also has an N249 acv on his toolbox, so i think it needed that too.