[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.

[coolwaterblvd]

Find some 99 and up cats to replace yours they flow much better and don't get clogged like the old ones. U should be able to find a set fairly easy from peoples take off parts.

[coolwaterblvd]

Also u will be legal! the new style cats only have a 200cfm drop and 2 should be fine and not trip your computer CEL.

[carnutz]

Yes I replaced with h-pipe with high flow cats. I live in NJ and they like cats on new cars. I like old cars with side pipes like my old 69 firebird I sold about 15 years ago. But the mustang goes around corners, gets much better gas mileage (the firebird got about 10mpg), not much rust, and most of the bushings are still good.

[pkstanger]