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I'm trying to start driving my RX-7 again, however registration is expired and I need to pass emissions. I live in Colorado. The car is an 83' GS, originally from California. The engine is completely stock and all emissions systems are intact (and presumably functional). I failed due to CO being over the limit, HC, CO2, and NOx readings were all within limits.
I assumed it meant the car was running too rich. I remember accidentally turning the mixture adjustment on the carburetor trying to set the idle speed awhile back. I tried starting with this. I turned the mixture adjustment clock-wise until the engine started running rough and then turned it counter clock-wise a bit. I've got the car now idling at around 750 rpm as the FSM specifies. The idle still moves around a little bit and it's definitely not rock solid, but it was idling at 1000 rpm prior. With the hood open and the engine running it honestly sounds a bit rough and makes a sound like when the turbos were going out on my 300ZX. The car drives fine though and the throttle seems responsive with a decent amount of torque.
The only other things I can think of is the gas in the tank is from last year I think. I meant to get the car running in the Spring, but they shut down the emissions stations due to COVID and I've just now got around to working on the car. Spark plugs also probably have a good 15k miles or so on them.
The frustrating thing about this is there's literally no way I can replicate the test so it's anyone's guess whether the car now meets emissions or not without going back to the station and trying again.
I can't imagine its your daily so register it as a Classic or Antique and don't worry about emissions testing ever again. Ive lived all over the country and most states (that I've been thru) are set up like this.
The frustrating thing about this is there's literally no way I can replicate the test so it's anyone's guess whether the car now meets emissions or not without going back to the station and trying again.
And that's why I went through our testing station 11 times before I passed. Literally would pull through, fail, then pull around into their lot, adjust a couple things, and pull through again. Rinse and repeat. Thankfully in Oregon we only get charged if you pass so it's only time and gas you're losing by doing laps.
I would definitely try some new gas. 8+ months on today's fuel without a stabilizer is certainly pushing the limit. Spark plugs and general tune up items would also be worth a shot, although replace the gas regardless.
I passed just a couple weeks with a lightly ported engine and a lot of other mods. Sounds like something in your car is just a little amiss - definitely start with new gas. While our cars are dirty by today's standards, a stock example should certainly be able to pass, although it might require a bit of poking around the engine bay. What's the mileage on the car?
I'll try replacing spark plugs and changing the gas, spark plugs are probably due for a change anyways. The car has around 70k miles on it. I'll look in the manual for how to check the air pump and check the ACV. I was honestly surprised I failed, because I passed with no problems the first time around. I'll need to probably drive it around a bit as it has quite a bit of gas in it right now. I suppose I could just empty the tank, but that makes me a bit nervous.
Unfortunately classic car registration in Colorado means that you only have to do emissions every 5 years, versus every 2 years.
Last edited by hcaulfield57; 08-26-20 at 06:32 PM.
Make sure your car has reached normal operating temperature before doing the emissions test. Besides what's been suggested above, check your air filter and O2 sensor.
08-25-20, 06:11 PM
