Help, my downpipe turns bright red
 

Where my Downpipe meets the rest of the engine it becomes bright red when my car is running for a minute? I have been told I need a new computer? Can anybody help me

Is it the stock down pipe?

It is fine. They all do that if they sit with no air flowing over them for a few minutes.

Are you sure? It looks like it is pissed off engine blowing red!!! yes its stock sir

It's probably ok, but you should get rid of the stock precat as it may be clogged and causing this to happen.

How does the stock precat cause that to happen?

It is restrictive, rescriction allows the heat to absorb into the pipe. If it is clogged it will be even more restrictive and thats bad. Worst case scenario they can break up and clog the main cat causing the exhaust to be blocked off completely, this very is bad.

It will even glow with a down pipe on it and no restriction. Ditch the precat if you haven't already.

my engine blew when my pre-heater got clogged. Car wasn't running right, opened the hood, pre-cat was glowing red and motor was blown.

There seems to be a lot of misleading info in this thread!

First of all, what mods do you have?

Are you talking about the stock pre-cat glowing, or do you have an aftermarket downpipe that is glowing?

If your aftermarket downpipe is glowing, it could be that your main cat under the car is clogged. This happened to me before on my old FD. I bought a used, low mileage main cat and the problem was solved.

The downpipe should NEVER glow red if the car is just sitting.

This is one of the major reasons the FD was not continued in US markets. The precat clogged too often, causing premature motor failure, yet Mazda had trouble passing emissions w/o the preact. So long story short, SAVE YOUR MOTOR. DITCH THE PRECAT.

~Ramy

ditch the main cat while you're at it

no matter what kick ass super unobtanium cat you think you have now, it will be toast within a couple of years with 11.5 AFR @ 1400F

resonated midpipe, heh heh....the car sounds downright mean with that, and the Pettit cat-back

I'm getting ready to terrify some rice very soon :)

If you still have AWS it will cause the downpipe (straight thru one not the pre-cat) to glow red as the AWS was designed to heat up the pre cat right away. It scared the piss out of me the first time I noticed it too. Now I always start my car in gear so the AWS doesn't come on.

start your car in gear? that really will stop the AWS from kicking on? hm, i'll have to try that because that stupid system pisses me off...

Dont laugh, what is a AWS. ANd to the questions earlier, everything in my car is stock. I guess I need to ditch the precat from what I am reading, So do I put it back on for emissions?

It depends how healthy your car is. I've passed emissions before with no pre-cat and just my main cat.

no you don't need to put it back on for emissions. Just make sure your car is warmed up or still idling before you take the test.

Also, you might want to spend some time reading the FAQ's (Stickies) on the top of this forum as this has been discussed before. I would focus on the "reliability upgrades".

AWS - "Automatic or Automated Warm Start" where the engine revs up to 3000rpm to warm up the precat.

You should be able to pass emissions with a main cat only. Ditch the precat and get a downpipe.

AWS = auto warm-up system (maybe? I don't remember what it stands for). When you start the car in neutral it revs to 3000 RPM and stays there for a bit to get everything up to operating temp. faster. It will start normally if you crank it over in 1st gear.

*edit* Damn, too slow :)

I wonder how they solved this issue with the rx8?

AWS = Accelerated Warm-up System

Me too :dunno:

The pre-cat is used to aid the main cat while the engine is cold. This is why you can still pass emmissions with the pre-cat replaced with a downpipe as long as your engine is warmed up. The Renesis engine is a sideport engine versus the RX-7 being a peripheral port engine. Due to this fact, the RX-8 has about 1/10 the emmisions of the RX-7. If you combine that with a much better understading of combustion and fuel injection, and a better fuel injection and engine control systems, it may be possible for the RX-8 to not even require a pre-cat. The elimination of a pre-cat could also be eliminated by using a heating element to heat the main cat to operating temperature rather quickly. This could also be aided by a better understaing by the Mazda engineers of catalytic converter functionality, efficiency, operating conditions, and designs that allows the RX-8 main cat to be moer effective than they could have been in the early 90's.

These are all just possibilities though and the only ones who really know are the Mazda design and test engineers. For all I know, the RX-8 may even have a pre-cat.....but I could see where it would be possible to engineer one out of the equation though.

Not a good idea.

YZF, it not's nice to set someone up for motor-blowing boost problems without at least a LITTLE warning.

Rickylil, there are several reasons why the precat or downpipe can get very hot:
1) super-rich AFRs, often caused by a leaky injector
2) a clogged main cat or precat. If the precat is original, replace that first with a downpipe. If the main cat is clogged, then replace it with another stock main cat. A clogged cat or precat will have loose stuff inside that shakes out when you remove the cat from the car.

If you open it up and install a through pipe or high-flow cat, you should have a boost gauge installed and carefully observe the boost levels. The midpipe is known for causing boost to creep above maximum settings, and it can even happen with some high-flow cats. Run a search for 'boost creep' before going to any kind of full exhaust.

Dave

That's what I thought, but I didn't want to say something I was unsure of. Thanks for the info :)

~Ramy

dgeesaman, you are the man