Car running rich and can't pass Ca smog
 

My 85 RX7 (I'm the original owner) with a 12A engine barely failed California smog as it was too high in the CO's. I took it to the Mazda dealer as it was idling kind of rough although it runs great at highway speed and seems to idle better after it has been run awhile. Thus far the dealer smog tech has made little adjustments to the carburetor and has come close but has not gotten the car to pass. He indicated to me that the engine is running too rich, but has not been able to figure out why.I have had all 3 cats replaced and we put in a new carb kit 2 years ago along with all the basic tune-up parts (plugs, etc.) Before taking it to the dealer we tried running carb cleaner and driving the car like crazy but still no pass. Does anyone have any thoughts on what else I can try? I suggested the O2 sensor but the head of service did not seem to think that was a likely cause of the problem. I admit that I am not a car expert, but want to keep my baby on the road in California if I can and would appreciate any thoughts on other possible fixes to my problem. I am also a newbie at using this forum and apologize in advance if I have not articulated my problem clearly or if I have broken any rules!
Thanks a bunch!

CA Smog
 

I was having the same trouble as you and here is what I did. First new plugs, wires and cap, and then tested all the solenoids, the air pump, and shutter valve. Once I verified that all of these were good my next step was to drain as much fuel as I could, then fill up with two gallons of 87 with two cans of iso-heet. I took my car to a facility that does repairs as well as smog, and explained my problem to the smog tech. He adjusted the fuel screw and the idle and was able to get my HC from 300 ppm down to 8 ppm. We actually had to richen the fuel screw, then adjust the idle and it passed with flying colors.

Not sure if this will work on you car, but It cured a car I had to smog with the same systems as yours.


78-80 12A Rx7 Air Control Valve (8342-13-720)

is it safe to assume "carb kit" refers to a carb rebuild?

new plugs are definitely a good idea right now. they may start and drive just fine after two years, but for emissions testing, they really can make a difference.

well, obviously, you want to run things a little leaner - even if you readjust after the test. you can also manipulate the timing a bit to suit your cause, and again, readjust after testing.

question: do you guys test at idle or is it one of those dynamometer tests?

in the past, I've had friends that swear by the efficacy of adding alcohol (products like Iso-Heet mentioned above). personally, I have no experience with them as far as emissions testing, but it is an option open to you.

as far as I know, none of the 12A cars came with an oxygen sensor - not even California spec. so I guess he was correct in stating it wasn't likely, but that sounds a lot to me like someone faking a clue.

stay away from dealers! they have one function/mission - to get as much of your money as they can, and they don't care how they do it. I wouldn't be surprised if after you paid, and the car failed, they didn't say the car is terminally broken so you should "talk" to [insert scumbag name here] about getting a new Miata or something.

you live in California. there are very knowledgeable - and moreover, HONEST -members all over the state. Gen I guys are arguably the most down-to-Earth of the 3 generations. you should spend some time seeking some local to you. they can help you out in times like this. they can also put you in touch with somewhere to have work done because taking it to a dealer is really a disservice to yourself.

Yes...the carburetor was rebuilt because new were not available anywhere we could find. I'll look into the new plugs based on your suggestion and someone else suggested replacing the air control valve so might try that, too! Found out that you are right...no O2 sensor on my 12A so rats on that!! I would love to find somewhere else to take my car than the dealer, but have been unable to find anyone else anywhere near my area so went to the dealer in desperation. Not at all impressed with them so far and they have had my car forever!!! I will try to keep looking for local help in the Sacramento area as once in awhile I see another RX7 so there must be SOMEONE out there I can link up with as I am not mechanical enough to do all this on my own!

Great suggestion on the air control valve! I will pass this on to the mechanic as I just saw that someone else had luck trying this. Thanks!

Car won't pass CA smog
 

Lots of good ideas...thanks so much!

nothing wrong with a rebuild. I just wanted to make sure that I understood what you meant by "kit". :)

yes. take some time and browse the CA Regional Forum. you should be able to find guidance to a reputable shop local to you. Mazda built the Rx-7 but didn't seem to give two craps about making sure their dealers knew what to do with them after the sale. I know ALL dealers are more expensive than they need to be, but for someone like you that may not be able to do things for yourself, you should at least be able to have someone that knows a little something about your car so that YOU get something out of the money exchange as well.

Car won't pass Ca smog
 

Hi there again! The mechanic says that the diaphragm on my secondary air control valve is hard as a rock and is not allowing enough air to the cats. Said the 3rd cat is not even getting hot. The link you provided shows it is for 1st gen cars thru 1980, but mine is an 85 and I don't know if this part will work. I also don't really know if the part you suggested is a primary or secondary air control valve. I actually do not have the correct part number at this time, but the dealer said he could not find one except maybe a reconditioned, which frankly i would take at this point! I don't think I have enough posts to go to the classifieds yet so I will keep trying to search. I really appreciate everyone's suggestions here...this site is amazing!!

For anyone else have problems like this. I'm using a electric air pump 3/8 one way metal check valve between pump and cat, single 18" cat and a laser temp gun to see if the cat is getting hot. Everything I bought cost about $250.

The cat is useless without the extra air from the air pump to make the unburned fuel burn.

where in CA?

Still trying to pass CA emissions
 

I live outside Sacramento, Ca in the North State so I am looking for other enthusiasts and their mechanic contacts up here. Supposedly there was a great guy in Yuba City, but he moved to Las Vegas, dang it! On the other hand, I guess the emission rules are much kinder there! :) So...on another note, I have learned that my secondary air control valve ( actually called a diverter valve) seems to be the culprit so I am trying to work through that issue. Like almost everything else on my baby it seems that SO many parts for 85 RX7's have been discontinued or are otherwise almost impossible to find. Wonder what it is about this year??? Anyway, I am pressing on and trying to not give up on my car eventually passing the emissions test although after almost 2 weeks at the shop it is hard to remain positive!!! I still believe it will all work out and I DO NOT want to give up my car!!
Thanks to everyone for their ideas and helpful info....