gwh

Hello all,

Our family has owned a '79 rx7 for 27 years now, and she's certainly served us well.

Recently we have been having problems with the catalytic converter, however. My dad noticed that after driving it home one night the converter was so hot that it was literally glowing red.

In a panic, he took it in and had the entire muffler system replaced. Now it sounds like a dream, but sure enough tonight he checked and the catalytic converter is STILL glowing hot!

I've done quite a bit of reading online, and discovered that common causes of this problem (aside from the converter itself) can include: faulty oxygen sensor, an incorrect fuel mixture, worn spark plugs or plug wires, a faulty check valve, incorrect ignition timing, sticking float, faulty injectors or other ignition malfunctions.

I'm just wondering if any of you have experienced a similar problem, either with your rx7s or with other vehicles. And if so, how did you resolve it?

In fact, right about now I'm willing to hear any of your theories. What do you think we should do about this problem? What would your next steps be?

Any help or advice would be greatly appreciated. You can reach me readily through email - ghoekstra@gmail.com, or otherwise I will be checking back in with this thread in the coming days.

Thanks everyone!

-gh

DriftFB

Besides throwing gasoline on it here are my ideas

- You can narrow odwn that list of things to check a bit, the RX you own does not have fuel injectors, so now you know you are dealing with a carb problem if it is on the intake/fuel side
-I am also not sure if the RX would have an oxygen sensor, seeing how it isn't fuel injected.

I would say start out small and do some work yourself to save money. Do the spark plugs and air filter, and if that doesn't solve it get a "colortune" engine tuning kit. These should let you get the air/fuel ratio right and let you know if the problem is more serious.

-I doubt it is the timing since rotaries only have to worry about ignition timing and that is controlled by a chain

85-GSL

yah you hit the causes right on the head, theres plenty to cause it. a good start would be search the forum and see what some other members did to fix it. also a full tune up would take car of it as well.

cdrad51

retarded ignition, and/or no air supply from air pump.

vipernicus42

iTrader: (4)

In my experience there are 2 reasons for a cat to glow red.

1. It's clogged. Replace it.

2. Your fuel mixture is *way* off.

In my case it was #1 AND 2.

You've replaced the system, so you know it's a fuel delivery problem. Do a tune up anyway because it can always help and your car probably needs it if it hasn't been done in a while.

Spark Plugs and Plug Wires, Dist cap and rotor

And then turn your attention to the carburetor. Where in Canada are you? If you decide to rebuild the carb, look for your nearest CarQuest parts store, they're the only place I've found that have 'Hygrade' or 'Standard' rebuild kits for our cars. Those are the best quality kits to use in rebuilding the carb. It isn't that hard to do if you have time and patience (it's akin to building a model car when you were a kid. You figured it out somehow, it just takes time and patience).

I can help you out, and heck if you aren't too far away I might even be convinced to come take a look-see (I'm in Ottawa).

Jon

trochoid

iTrader: (6)

Lets clear up a few misconceptions here.

Carbs can have a an O2 sensor, they work in closed loop mode and generally only affect afrs during a steady state cruise.

Timing is driven by a gear on the e-shaft, not a chain. Timing can be adjusted like any other older style distributer engine, It cannot be controlled by the non-existent chain, hence the dizzy.

Timing can greatly affect exhaust gas temps. Which may be one of your problems. Check the timing, it may be retarded too much.

If the spark plugs are old, a fresh set wouldn't hurt.

The SAs, 79-80 models, do not have cats, they have a thermal reactor. These tend to collapse over time and plug, causing a noticeable drop in performance.


If the car will run through the gears with similiar acceleration as before, limit the initial checks to timing and carb. Timing doesn't change by itself suddenly, but as the points style system in the SAs wear it will change gradually.

I would start with a fresh tune-up and look at the carb. The floats may be sticking, the choke buttefly may be sticking, etc. Run a can of Seafoam though the tank, it will help clean the internals of the carb.

gwh

Thank you all for your help. We have been tinkering with the car all day, and it's doing a little better, thats for sure. For some reason rotating the distributor 180 degrees has kept it from glowing red...on a short term basis at least.

We're still looking in to look into other things though. Something funky is certainly going on.

Again, thanks for all your advice -- it's appreciated!

rOtAryIsbEttEr

get a long screwdriver and a decent size rubber mallet and whack a hole through it. it'll prolly stop glowing