So I got a 93 FD Catalytic converter welded into my 3inch exhaust 2 weeks ago, and yesterday I had to make a 2 hour hike in my FC back to the Coachella Valley from San Diego. I expected her to get hot in the desert, but I was still in SD and going up hill I noticed my temp gauge was slightly over the middle mark. So I let off the gas and it went down again. I never really did this before. The only things I've changed on the car since I've been on the freeway was rewiring the fuel pump(which did wonders for my car), and install the Cat. The shop said that I should have 3 cats on the but they said one newer car from the later model would probably work pretty well. So I let them do it. My question is, has anyone experienced engine over heating problems after installing a beefy cat? Am I going to have to remove this thing now? I already have a beefy cooling system. Koyo Radiator with water wetter, stock fan + electric fans.

 

are you feeding the cat with the air pump?

2nd stage reaction on the FC cats need the O2 from the air pump (although most of that is dumped when you get into 5th gear cruising) as the fuel injection is not as tight as later models.

 

I guess that would explain some things. The air pump was removed. and it is capped at the cat. I think I have one sitting around somewhere I can hook up. But on the free way I am pretty much 100% in 5th gear. It only seems to raise when going up hill.

 

without an air pump, the cat can overheat if your mixture is not perfect.

At 5th gear about half the air is dumped out (when compared to lower gears) but there is still quite a bit being put into the cat. This doesn't help the first stage in the cat, but will prevent the 2nd stage from burning up.

Also a dirty or partially clogged cat will over heat easier, as will too rich or too lean of a mixture. What are you using for injection and timing control? The stock ECU? Tweaked ECU?

And your signature picture is about twice as big as allowed (19.5 kB is the largest allowed, yours is 37.14 KB (38031 bytes)).

 

Stock ECU, Brand new Stock Sized injectors. Think I should throw the air pump on there?

I didn't think it mattered if it was hosted off rx7club. I'll change it then.