EEC + 180* T-Stat + Cold Weather = Bad Cat Conv

Gentlemen,

I've recently moved from the heat of Texas to the rain and cold of the Northwest. Since getting here, my gas mileage has plummeted (18 --> 13 mpg in city). I eventually burned out a catalytic converter (Magna flow Hi-Flo Cat).

I suspected that my T-Stat was stuck open and it was. Replaced it with another 180 T-stat, changed all of my spark plugs (I was running the Autolite 24s for Texas, now back to the 25s and BTW, two plugs were fouled), and got two new O2 sensors.

I got a new Hi-Flo cat welded in and here we are 6 weeks later and it's toast.

Here's where I need you Tweecer Dudes' help:

The T-stat is working perfectly. It just takes a long time for the engine to warm up. By warm up, I mean barely to the N in NORMAL. The cold weather here is also not helping the situation. I suspect the EEC is saying, "Hmm, it's cold, more gas". This is causing me to run extra rich and that has lead to burning out the cat.


If I had a Tweecer, would there be a way to tell the EEC that you have a 180 stat and you don't have to run so rich?

I think the fix in the meantime is to go back to the OEM stat and change my plugs again.

Thoughts?

Gracias,

Bchilt

I'm not sure that I've lost a cat anymore. I'm not smelling rotten eggs like before. I need to isolate the tapping sound. It could just be an exhaust leak.

A Tweecer is next on the purchase list. I need to see what's happening.

Hey '87 Rock,

Thanks for the response. I have reposted this in the tech section but, yes, I'm thinking along the same lines as you. In fact, I ordered a new ECT sensor but am holding off until I pull the codes.

A tweecer or TwEECer, as the tuning dudes write it, is a tuning device that allows you to read and adjust the Electronic Engine Controller aka "the computer" in your mustang. I really should type it this way: TwEECer, to avoid confusion.

Thanks again!