Hello all,
I hope some one can help me with this. i am not a mechanic and have just started getting into this stuff. I appreciate any help or advice so I can try diagnosing this issue. Thanks

About the car:
1990 Firebird Formula 305 (F) TPI sitting for 10 years (only started occasionally)

So here's what's happening:

The cat is fine when the car just idles. I let it run for 20 minutes and it did not glow at all. The cat glows red and the floor pan gets hot when driving 10 minutes or so. It also does it if I'm idling and I rev the motor a few times. Now when I rev, it backfires pretty loud when I take my foot of the accelerator.

The exhaust manifolds are not glowing, but they do seem pretty hot. There are pinging sounds from near the valve covers and under the car when I shut it off.

The car is not overheating. The temp after driving around for 10 minutes is about 200. It's like 90 degrees outside here.

There is no check engine light

The idle is a little rough especially out of park. It doesn't stall, but it hops around a bit. Even when driving it feels a little rough. Almost sounds restricted

I know the most common reason for a glowing cat is that it's clogged. This cat is brand new and the old one I took off was not clogged either. I put the old back on for now until I get this figured out. The muffler was a new Flowmaster 10 years ago I had installed just before I took the car off the road. Could that be clogged and cause this? My friend told me animals like to nest up there and cause all kinds of clogs. I haven't noticed flaming chipmunks flying out of my tail pipe yet.

Here's a video of what it's doing with the backfire.

Here's what I've done so far that's related to the issue:

New catalytic converter
New spark plugs and wires
New distributor cap and rotor
New O2 Sensor
New coolant temperature sensor
New air filter
Coolant flush
It's worth mentioning that I had added fuel injector cleaner and dry gas into the tank. I have about 7 gallons of gas in there now.

 

Glowing usually indicates lean, so could be low fuel pressure due to a failing fuel pump. I'd also look at injectors and/or fuel pressure regulator.

Got a fuel pressure gauge?

Can test injectors with multimeter, sometimes will test ok and still be sticky though.

 

Thtanner,
Thanks for your reply.

I was afraid it might be the injectors dumping too much fuel, causing it to be rich and burning excess in the cat. I didnt know lean could cause this also.

Never did the fuel pressure gauge test. Guess I will pick one up and start reading.

I bearly had any gas in the tank when it was not running and had put in a stabilizer. When I worked on getting it running I put in about 7 gallons of fresh gas, injector cleaner and dry gas to kill any moisture. I should proabaly replace the tank, pump, sending unit (its bad any way) and filter in one shot.

 

Hate to be contradictory but if you google "catalytic converter glowing red" your gonna get about 1K responses that it is too RICH , the excessive hydrocarbons literally burning in the converter .

 

Sticky injector could do that for sure. Sat for 10 years, probably stock ones.

Swore I read it was 'red before the cats', but a re-read of the post proves otherwise.

 

Yep. I had done that. Now I have to figure out why. Timing, temp sensor (even though mine is new) ignition control mod, injectors. Keep in mind it backfires too which I though would be timing or vac leak somewhere. Not sure if any of that would be related to it running rich

 

Done it plenty of times myself , respond to something I would swear I saw in a post only to find I read it wrong . Anyway , another possible reason for raw hydrocarbons making it into the converter in sufficent quantity to cause it to glow could be retarded (late) ignition timing . If the spark happens too late , the still not quite fully burned fuel ends up pushed into the exhaust and finishes it's burning in your catalytic converter .

 

I've had this happen with my Lumina when I lost a coil pack and had to drive 15 miles to get it home. It was enough to fubar the converter.

 

Would late timing explain the miss fire? I was thinking it was a timing or other ignition issue first because of the miss, rough idle, and hessitation.

Again I'm not great with this stuff (yet) and I'm sorry for the dumb questions. I'm learning some of the comon sense around eveything.

 

Yes Sir , Late timing could cause those symptoms , but here's the thing , I'm gonna let you in on a little known mechanic's secret here ;

As long as the hold down bolt (or nut) for the distributor is tight , the base ignition timing NEVER changes by itself ! In other words , if no one has dinked with twisting the distributor in an attempt to fix some running issue or other the timing will be correct and your problem will lie elsewhere . Now , it will take literally five minutes to rule out the timing , hook up a timing light , unplug the EST connector , and check the base timing . If no one has moved the distributor it'll be fine , but just to eliminate that possibility that someone has messed with it , check it . Now if the timing is correct and not late , next you go looking for a leaking injector or regulator . How ? Simple , you check the fuel pressure both running AND sitting shut off . When it's shut off , the system still must hold pressure , if it bleeds right to zero upon shutdown that's a good indicator of a leaking injector or regulator . The bottom line here is , you have a very definitive set of symptoms , there are only so many malfunctions that could cause those symptoms and in proper troubleshooting technique the real problem will reveal itself if the tests/checks are properly done . So , it sounds like a timing light and a fuel pressure gauge are in order here , and a cylinder compression check wouldn't be a bad idea either , if for no other reason to assure a weak cylinder isn't contributing to your lack of power issue .

Good luck and please report back the findings of the fuel pressure / fuel rail leakdown check as well as the timing check . And note that I said check , at this point your checking things , and not changing things , throwing parts at a problem without a test indicating that part is in fact bad is a good way to spend a lot of money and still end up missing the actual problem ...

 

I will definitely post my finding. Thank you for your help

 

Your welcome , and BTW ,

I never usually use the expression LOL cause I feel it's SO overused as to have lost a bit of it's kick . But when I read this , and got the mental picture of Alvin , Simon , and Theodore flyin outta that tailpipe deep roasted to a crackly crunch , well yea , I'll admit , I LOLed all over the place !

 

The converter is glowing since it has WAY too much fuel to burn. Your converter is definitely working. The backfire on decel also proves this...excess fuel in the exhaust. I just had a set of 2300 mile reman injectors do the same thing. AND I couldn't get warranted since it's a street rod that sits. 2300 miles in 3 yrs. Just put in a set of Summit AFIS USA made injectors. Problem solved...I'd change as a set a do new unless you can't afford it. OHM meter across the injector should be 15-16.5 ohms.