Red Hot Cats?

[Mentat]

93 GT, 5 speed.

Tonight upon starting my car, it hesitated and I heard what can only be described as a swoosh or a sucking sound. A few cranks later, it started and had an intermittent idle problem.

I made it home no problem, but I did smell either oil or plastic burning. Upon inspection, I could find nothing under the hood out of place. With the car running, I went to the back of the vehicle to see if I could smell if it was running rich or not.

The only thing I could see were my cats glowing red hot. Is this common? I'm pretty sure that I've seen my cats at night and they were not that hot.

Advice?

edit: I'm running the stock cat with some Flowmasters.

 

[dcurtis]

I think when they glow it means they are clogged.

 

[ID89GT]

Do you still have the air pump

 

[HISSIN50]

You can use a manifold vac gauge to test for an exhaust restriction. Hold the RPMs very steady at 2500-3000 (in that range, but pick one and hold it rock steady) RPM and watch the reading. If it starts to fall after anywhere from 10-60 seconds, that suggests an exhaust restriction.

 

[FORDBOY1516]

do you have the stock dizzy on it? do you have an exhaust leak? by the headers?

 

[GreenDragon]

I had a similar issue with my 92 after leaving it parked for several months. I started it up, and it idled erratically. I left it running in the driveway for a while to charge the battery, and noticed that my cats were soo hot that they were melting the underbody coating onto the ground in puddles. After changing all the wires/rotors/plugs and cleaning the MAF, it still didn't fix it. I then pulled codes and saw my ox sensors were all pegged at zero. Read about that condition on this site, and one of the reasons was too much air going into the engine unmetered by the MAF. I started it up and really listened around the engine, and heard a sucking sound which I identified as coming from a broken hose connecting the charcoal canister to the underside of the intake. When I plugged this hose, the idle smoothed out, and the cats cooled down. So your sucking sound may be coming from a broken hose letting air in. You can either poke around up front while it's running, or buy a can of starter fluid to spray around the engine to locate a potential vaccuum leak. Good luck!

 

[Mentat]

Thanks for the replies.


I have the stock distributor, air pump hardware all in place, and no exhaust leak. I will try the restricted exhaust test this weekend and will also start tracing vacuum lines (this time in the daylight!)

The sucking sound I described only happened right when I started it up, almost sounded like something got sucked through a pipe or some ****.

A buddy of mine said to check the AIR pump diverter valve, as a faulty one could cause a lean running condition. Any credence to this?

:SNSign:

 

[HISSIN50]

The diverter doesnt cause a tangible lean condition but it can deprive the cats of the air they need.

 

[Mentat]

Well, I spent the better part of two hours checking vacuum lines, connections, you name it to no avail.

No chance to do the aforementioned exhaust pressure check, but I have another question: would not any other problem leading to a lean condition that creates exhaust hot enough to make the cats glow not also make the headers glow?

The car does not smell like its running rich at all.