Clogged Cats

[carnutz]

Well I thought that I was a good mechanic and troubleshooter having worked on cars, and motorcycles for 20 years. But I was stumped when I had clogged cats on my 94 mustang.

The mustang is a 94 GT with (76mm mass air, 70mm TB, cold air in fender, ported intake, flow masters, 3.73 rear, Tremec 5 spd trans, aluminum drive shaft, lightweight alloy wheels, 2” lowering springs,…) The car was very fast, then one day it started getting slower and slower.

In the end the car would not go over about 4000 RPM and if you went WOT at high load it would sputter and buck. I did a full tune up and replaced everything including: (1. new plugs cap rotor, 2. new plug wires, 3. Fuel pump), and could not find the problem. Finally out of desperation I replaced the h-pipe and almost hurt my neck when I went for a test drive expecting the same slug like acceleration and it took off like a rocket.

I am writing this because it took me about 3 weeks and a lot of work to find the problem and am hoping this can help someone out there. The car had the stock cats on it and one of the pre cats had melted gone down the exhaust and clogged the next cat real bad. Also the car is faster then ever the stock cats must have been having problems for some time, Talk about a HP gain.

 

[86bluecobra]

Yes Cats are a funny thing sometimes it can take a long time for them to go while in my case it was quite literially over night that they clogged. I started a trip about 1 1/2 hr in i blew vacuum hose off my engine because the exhaust had no where to go. I got them cut off when i arrived in the next town. A trip that would have usally taken me 45 min from where i was took me 1 1/2 hr and I also went through 3/4 a tank of fuel in that 1 1/2 hrs. The vacuum line going to my maps sensor melted off. The ford guys said my maps sensor was no good wanted around 500 dollars to fix my car. I asked how much vacuum line was and bought 2 feet of it. I hooked all the lines back up and it ran like a top. Stupid cats anyways.

 

[cardudeusa]

What exactly is a cat?

 

[jrichker]

What exactly is a cat?

A cat is a furry four legged creature that sits by my home computer and fusses at me because I am ignoring her.

On my Mustang, a cat is the catalytic converter that helps reduce exhaust emissons by chemical catalytic reaction. It uses the catalyst, air from the Thermactor Air System (smog pump) and heat to break down the harmful components of the exhaust into CO2 and water.

 

[cardudeusa]

Yeah, that was my reaction when pulled over and the officer says "I bet you dont even have cats do you?"

 

[4G-KDMP]

this is good information to know.

 

[bloopbloob]

platinum! mmmmmmmm

 

[jimdrechsler]

i was told that if i hollowed out my cats that i would be slower than if i didnt. i have a h-pipe with cats on there. i was questioning whether or not they were clogged or not. shouuld i gut them or leave them? can it hurt me gutting them??

thanks

 

[Red88 RICK]

i dont deff know if gutting them hurts them but when i bought my car it came with BBK off road H-pipe (no cats) and what i thought was a stock catted H-pipe i was worried about emmisions and or inspection and thought about putttin my "stock" hm pipe on and notived that very professionally welded a tag saying off road use only and then finally noticed soemone welded up teh cat also so someone must have gutted them looked professional so idt it would hurt or at least i dont thihnk it would make sence that it would hurt you in HP

 

[jimdrechsler]

maybe ill have my mechanic gut them. may be too loud though?