wat are the most common reasons for a glowing down pipe?

 

extremely high RPM and high boost

There are a couple videos out on the net, ie youtube, that show a single turbo FD doing a Dyno run where the pipes glow cherry red they're getting so hot.

 

wat about glowing red at idle?

 

Might be a tuning issue, what are your mods?

 

Are we talking about a stick DP with the pre-cat? If so the cat may be plugged.

If it is an aftermarket down pipe, do you still have the air pump hooked up? I have read that it is normal for the top portion of the downpipe to glow during start up (when the air pump is injecting air into the exhaust stream). And of course after hard driving. Again this is just what I have read so I am not sure if it is 100% correct.

 

Your main cat might be clogged...

 

Incorrect ignition timing will make the DP glow also

 

you should wrap it up with some header wraps to keep that heat in...

 

performance engine mods are aftermarket rx7store.com downpipe with highflow cat and hks exhaust. everything else is rebuild and replacement parts here and there to get the car running straight again. my cat is new so i doubt its plugged. i think NTIMD8 might be correct about the air pump theory. mine has been acting up lately. i know i wont pass emissions but will it mess with the car if i remove the air pump with the stock ecu?

 

I don't have to deal with emissions in my state, but from what I've read, you won't pass in California w/o an airpump. I'm still running my AP but it's never gotten close to that hot at idle. Something is wrong.

 

actually now that i think about it my factory blow off valve has been blowing out a lot of air at idle and start up. iv tried several different bov's and all of them did the same thing. me thinks the air pump scenario might be a winner.

 

The stock BOV will intake a little unfiltered air under vac, and make noise. But it wouldn't have any connection to the AP or cause your exhaust to run hot.
The AP running continuously or malfunctioning somehow, or an obstructed exhaust would be my suspects.

 

i was thinking maybe the bov letting off a crap of air at idle and not just a lil might have been caused by a malfunctioning ap. wasnt doing that before. both started acting up almost at the same time. but i think i wanna get rid of the air pump completely i don't need to pass emissions. has anyone done this mode before with a stock ecu???

 

I had a glowing dp when my injectors weren't flowing right. I suspect the excess fuel was burning in the dp during the cold start sequence.

Dave

 

that makes sense too. congrats on the 8000 post.

 

Id agree maybe your running really rich and its burning in the downpipe... many people have had glowing manifolds because of running rich at idle, dont see why the same couldnt be true for the downpipe as well.

Chris

 

Either running very rich, or very lean......hope for your sake and your motor's sake that it's running rich.

 

Uhh, running rich actually cools the heat down. It's lean thats causing high temperatuure just like heat creats NOx, and NOx are created under heat/load. The air pump could be the culprit. BUT, you might wanna check the AIR-BYPASS valve, if its always stuck open, constantly throwing air down the exhaust port (downpipe), it will create extreme heat which will cause the downpipe to glow.

 

Rich in the combustion chamber tends to bring down combustion temps.

Rich to the point of causing afterburn in the exhaust leads to much higher egts. That's how a downpipe will glow from running too rich.

Dave

 

Can malfunctioning/leaking injectors cause the exhaust canister to glow red inside and blow a small constant fire out the tip, during idle <<<???

 

Never Ever do that!! hedder wrap does not work on rotarys the headders get so hot that after a couple of days it just burns it up! speaking from personal experience, and it messes up your exaust piping if you got aftermarket because its much thinner it weakens the mettal and leaves the headder vonureable (sp) to crakin....
so in other words not recomended....

 

I'm not recommending it to the OP as a solution to his problem....but header-wrap works just fine. I've had my DP and exhaust fore and aft of the cat wrapped for more then 3 years now and it's still going strong. Along with heat coatings, I think it's a widely accepted solution for reducing radiant heat, noise and underhood temps.

 

The only time I've seen glowing down pipes or manifolds on rotaries has been when the fuel and timing were out of whack. Rotaries run fine without air pumps and any other emissions related components. Just look at those with simplified setups under the hood.

+1 on header wrap being OK , it keeps the energy where it belongs - inside the exhaust. If parts of the exhaust system are glowing, header wrap shouldn't be used until the root cause is determined

 

It's not uncommon for the downpipe to glow a little after a hard run, and I wouldn't be surprised to hear that your downpipe glows after simply idling for extended periods of time.


The stock ECU retards the timing when idling, according to the service manual the leading coils are firing 15 degrees after TDC. This will begin the combustion process late, possibly even allowing some of the air/fuel mixture to continue burning while travelling through the downpipe. This isn't necessarily a bad thing, however: if you ran ignition advance at idle, the parts inside of the motor (rotors, housings, etc...) would heat up more. I wouldn't worry about it too much.

-s-

 

^^^my exhaust manifold glows after ~20 min of idle so that's ok then? I thought that there's a problem. I've never seen my dp glowing though.