I searched the archives on this subject and came up with many different reasons for the downpipe glowing but couldn't find one that related to start up only. This is what happens I have a pettit downpipe with a pyrometer installed. When I first start the car it runs a little rough not bad just some little hiccups out of the exhaust I popped the hood and noticed the downpipe glowing I looked at the pyrometer and it was at 1400 degrees Fahrenheit I let it run for a while watching the temps and all the sudden the idle slowed down and the temp dropped to 10000 degrees Fahrenheit and it idles perfect I don't know what could cause this to go away after about five minutes i have tried playing witht he accelerator and everything with no luck please help thanks

 

During startup the stock ECU runs quite rich. So you're seeing afterburn in the downpipe which is pushing up EGTs.

Since orange-hot is a little extreme, I usually only let it idle for 10-20s and let the car warm up on the road. If you avoid big hills and accelerate gently it warms up within a minute or two and you don't see those crazy hot temps at the downpipe.

Dave

 

That is really extreme!
Your main cat might be starting to clog up too.

 

I dont think its a clogged exhaust because he would see high temps all day long and not just at start up. maybe burning gas in your down pipe, but if i had to guesse I would have to say it could be running lean at idle. Do you have a wide band or know some one?

Also what mods do you have? it might help some of use figure out whats wrong.

 

sorry i got a little zero happy it is 1400 then it drops to 1000 I have no mods but the downpipe and pyrometer and a boost guage i am tryging to keep it almost stock to avoid problems. thanks

 

How many miles on the car?

 

Mine does this every cold morning.. Rough idle, very hot downpipe, idle smooths after ~ 2 minutes, DP cools off, and I drive it happily away. Been doing it for three years, nary a problem (well, blown coolant seals, but that was from the first owner )

 

I called a mazda dealer near me about the temps they didn't know much of anything so they called mazda hotline in japan and i guess from what they say it is all within spec and normal. thanks for all the help