I recently bought a 1981 RX-7 GSL with an NA 12A (obviously), 102k miles. All stock. I live in Portland, Oregon. This morning I took it in to DEQ for the mandatory emissions test (required before I can register it). The HC standard is 220 PPM. I failed with 237 PPM on my first idle, and 267 PPM on my second idle (2500 rpm).

Since I was so close, I wanted to give some of the old standbys a try. I had already replaced the air filter and the plugs. I decided to buy a couple bottles of Iso-HEET and a bottle of Chevron Techron. The car had a full tank of gas, so I ran it down to about 3/4 tank and put in all three bottles.

Then I drove the crap out of it for about 30 miles back to DEQ. By the time I got it there, it wasn't running very well (idling at 3000 rpm), so I swung into the gas station and topped it off with 87. Idling came down to 1000 (normally between 600 and 700) and I drove into the testing station.

MY HC CAME DOWN FROM 237 AND 267 TO . . . 32 (thirty-two)!! They didn't even make me do the second idle at 2500 rpm.

On the drive home I think the 1/3 tank of fresh fuel mixed in pretty well and the idle came back down. In fact, now it's idling a little lower than I like and died once. But the moral of the story is, before you go replacing your cat, give a little alcohol a go. It might just do the trick. I probably should have only used one bottle.

Now the question is (for those of you who've read this far), should I siphon that gas out and replace it entirely (run that stuff through the lawn-mower instead)?

 

dont worry about it...

 

what is ISO HEET?

 

ISO heat is alcohol for pulling water or ice out of your gas mainly in the winter time.

I'd just keep driving it the way it is. You can push anything through the rotary and it will run fine. You must have sticky throttle plates or cams if it stuck at 3k. maybe the choke was stuck. That would explain the higher numbers on your test.

Seems like maybe the heat worked for you, but next time try Seafoam

 

Seafoam ftw

 

interesting

 

I read on the website that makes iso HEET has methanol and isopropyl alcohol. So pretty much it worked for the OP because methanol is not a HC aka he did the "alcohol trick" to pass the smog test.

 

works for me, use it everytime. 4 bottles in one gallon.

 

do you guys think you could pass using heet with no cat's?

 

I doubt it. w/o cats all the measurements are through the roof.

 

You also probably heated the hell out of your cat while running the **** out of your motor for the 30 miles back to the testing station. Hot cat = cat that works really well.

I had a professor at school that used to live in Boulder, CO. He knew that his C4 Vette wouldn't pass emissions w/o an extremely hot cat. He would drive the hell out of the car and make sure he rolled straight onto the dyno, with barely any idle time. His cat was hot and he passed with flying colors every time.