ive got a friend who just bought an 84 gs equipped with a full racing beat exhaust. to my knowledge everything else on the car is stock. my only question is that when the car is first started up (with the choke on) the headers will glow red within maybe 15 seconds and stay that way untill it comes off the choke. is this normal / ok? i know my turbo used to glow when i was really on it hard, and my pre-cat glowed when it got clogged, but other than that ive never had anything glowing. it seems to be fine other than when its on the choke. my only thought was perhaps its getting super rich or maybe lean or something... maybe burning in the header as well as inside the engine. anyone know more about this?

 

ok i apologise for not searching bafore i posted. god youd think i was a farging noob.

hes replacing the coils this weekend. checking timing and other tuneup stuff this weekend also. if i cant figure this out i may repost.

 

Wow,

Well Vash, I must say I'm impressed. Good search job. This isn't a topic that comes up often, so chances are we probably wouldn't have said "search it up"... I know I only really tell people to search when they ask things like :
- what kind of spark plugs should I use
- is synthetic oil okay?
- how much hp can I get with this setup?
- What kind of fuel should I use

and other things that come up at least twice a month... but I can't say I've seen glowing headers on here often!

Keep up the good work

Jon

 

Choke causes rich mixture; this is to help the engine get up to operating temperature faster so that the cats can start working (when they're installed), and so that the engine will have enough compression to keep running in cold conditions. The choke effectively caps off airflow into the engine with the same amount of fuel going in, therefore you have an overly rich mixture to burn, which keeps the engine running when a lean mixture would cause the engine to hunt and then die.

The reason why the header is glowing with the choke engaged is because this excess fuel in the mixture is not getting burned in the combustion chambers, which leaves unburned fuel flowing through to the exhaust where it's burned against the hot walls of the exhaust tubing. This is why the header is glowing red.

The only way to fix this is to either 1) not use the choke, or 2) change the idle mixture adjustment for fuel and/or cut back the amount of 'choke' used, i.e., adjust the position of the choke baffle so that it doesn't block off as much airflow.

Cat's glowing red hot is usually due to clogged cats and overly rich mixture. Since catalysts are designed to burn unburned fuel, you can expect that they're going to get hot, and hence the reason why Mazda installed a temperature sensor under your passenger seat to alert the driver of this condition when it gets out of hand. Also is the reason why you should never drive over or park your car on top of dry weeds or other flammable materials - those cats stay hot.

 

Thanks LongDuck, or Do you prefer to be called Mr. Dong

That seemd to clear that up. When I read the post I went and did a search, and the search resaults were less then diesireable.

But your answer has cleared any confustion generated by the search