What's up everybody! So it seems that not a single person had had a problem with a glowing DP since the big market crash of '08... All of the search results are old and stupid. All saying different things and not even getting to the bottom of the problem... So hopefully in 2013 we can tackle this damn question.
Is it normal, or is it NOT normal for your downpipe to glow at idle?
I have a 93, and I JUST got my motor rebuilt and streetported by Banzai, and finally got it to run a few weeks back.
Mods are: streetport, intakes, downpipe, and catback.
During the rebuild I sent my injectors out to RC for cleaning so they should be fine. I don't think they would send them back to me and not tell me anything if they were sticking or leaking..

The Problem: Fired up the car and drove it around for an hour or so. No boosting since i have to break it in after the rebuild, and not driving hard at all. Then I parked the car and left it idling for 45 mins-1 hour. That's when I noticed my Turbos on the exhaust side, and my downpipe glowing bright red. It was eveningtime so it was easy to see them glowing bright red. I shut the car off, waited about 30 mins, and started up the motor again. After about 15-20 mins of idling it was glowing red again.
SO. Is this normal or not?
If it is not normal, where do I start in order to diagnose and fix the problem??
Thanks guys.

 

Clogged cat? Still running OEM?

 

Sounds like a clogged main cat (mid pipe...).

 

Also could be a bad leading coil.

 

To answer your question, it is NOT normal.

First thing came in mind was clogged cat.

-AzEKnightz

 

Don't assume those injectors are ok. I've seen it happen where the cleaning varnish causes them to stick closed, usually when they sat for a while after cleaning. For this reason I always run voltage through cleaned injectors before installation.

 

have you checked your timing? assuming you have some kind of ems....

 

I would say coils.

 

Did you ever fix your idle and plumbing problems from this thread? https://www.rx7club.com/3rd-generati...2A%2A-1023285/

A 3K idle and bad vacuum leaks will cause your turbos and DP to glow.

 

Check timing too.

 

So a lot of you guys are hinting at a bad cat huh? I suppose it could be that. I have a DP so flow shouldn't be too restricted. But my cat IS really old, probably had never been changed and is probably at 100k now.
Timing on FD? How exactly would I go about to checking that? I have the stock ECU, no ems, and I never messed with the pin on the crank pulley, and the crank angle sensor is good.
Hmm, Why would coils affect this?
That's funny because in none of the other threads did they mention coils, but people would constantly bring up injectors.
And yes Banzai, I took care of all those other problems.

 

See it doesn't glow while driving. Only after I come back from a drive and the motor idles for 20-30 mins or so after that.

 

Is that 20-30 seconds or minutes of the motor idling?

 

I believe minutes.

-AzEKnightz

 

Yeah, it's definitely minutes.

 

Buy an OBX resonator to bypass your cat. Order the correct flanges, weld them on and enjoy the best sound a rotary can make. $39 for the pipe $14 for the flanges.

Not very many people appreciate the sound of a rotary but since I've bought this pipe many have complimented me.

 

Back in the day of playing with Mopar engines (think 383, 440, 340, 318 etc) retarded timing and rich fuel ratios could cause exhaust manifolds to glow.

Reason being, unburnt fuel is making its way through an engine and then combusting in the hot exhaust manifold, which heats it up and causes it to glow if left to sit at idle like this for a while.

Back before the days of electronic data logging, people used to use the crude method of painting a paint strip over each header tube out of the side of the heads. The header tube that cracked or blistered the paint was not running correctly in that cylinder and the mixture/timing needed looking at.

Why would I be bothering to tell you all this seemingly useless cylinder-related malarky?
Because running rich and having the timing too far retarded is not just a piston thing. Its completely applicable to a rotary as well. Go check your timing numbers (degree advanced/retarded at idle and off boost) and check your AFRs and see what you have. I'll put my 2 cents in that this is whats wrong. Because I've seen it on other engines, and most of them werent running cats either.

 

I'm curious, why the car would be idling for 20-30 minutes? You'll have no airflow into the car so it will run hotter.. The stock based ECU's run fairly rich at idle so you'll likely see the worst case of unburnt fuel/rich running during that time.

 

Sa3r is right.

Also make sure u check all ur coils. This could be adding to incomplete combustion. A quick way to check is with a trimming light. Look into replacing ur stock leadin igniter with a MSD box.

 

Yeah I think you guys might be right. Because my car even sometimes idles weird too, like its misfiring randomly or something.. I will check on the leading coil. What should I do to test it?
Mahjik, its because im just trying to let the engine run as much as i can right now to let it get all settled in right after the rebuild. I just got it running..

 

the cat that get clogged is it the one closer to the back of the car?

 

a rebuilt engine will run the exhaust hot for a short while, but it shouldn't last for more than about 30 minutes to an hour max until the seals seat in initially

a faulty leading coil or plugs/wires would cause the engine to run retarded and off the inferior trailing ignition, running the exhaust hot and lacking power. the timing is locked and cannot be tweaked but if the plugs aren't firing properly or wires crossed then this could also cause it

a plugged up pre cat would also run the turbos/downpipe hotter, a plugged up main cat would do the same but to a much less extent and only really after boosting it

vacuum leaks cause the map sensor to correct fuel requirements, running the engine richer, causing the exhaust to run hotter. with a stock ECU you can only fix the vacuum leaks to correct the problem, with a standalone equipped car it can be tuned out which makes it a little more difficult to know there is a problem besides the vacuum reading low on one or both rotors