Reprinted with permission from the Alamo Area Fiero Owners Newsletter August 22, 2001
The underside of a Fiero can be a hard place to get to considering the fact that it sits a mere 6 inches above the asphalt. But every so often, I tend to find myself performing an oil change or troubleshooting a leaking fuel tank (talk about a reason to go BOOM!). Anyway, in the knowledgeable words of AAFO member and tech expert Glenn Anderson "My gosh Rob, you still have the old catalytic converter?!?!?!" Fact of the matter is, (and yes, I did come up with this myself) how much better would the car run with a new one? I would imagine that it is like the brakes on a vehicle, you really never know you need them until its past time to need them. This is possibly the same with the converter, but with less drastic results than brakes. A worn converter can rob you of power and torque at such a gradual state, that it may not be apparent until you replace it.
Case in point, I recently acquired an 88GT that ran fine, but didn't quite seem to have the edge that other six cylinders that I owned had. A casual inspection revealed-the stock converter was still in place. Subsequent replacement restored that edge that it had been missing and I once again was able to drive with a big smile on my face. Converters typically will last anywhere from 50 to 100 thousand miles before they become more of a hindrance than a help to the performance of the engine. I have been counseled by several muffler shops that in actuality, the converter should last the life of the vehicle, but that only occurs if the vehicle is in perfect running condition ALL the time with regular tune-ups, regular replacement of the Oxygen sensor, and things like that. Well, unless you are the original owner of your Fiero, chances of this are slim to none. So, what is the job of a catalytic converter, and what causes it to go bad? Well, the job of the converter is to burn the residual fuel that the engine did not manage to burn. This boils down to factors from how recent your tune up is to how clean your air filter is. Over time, the converter begins to clog up with this residual by-product thus restricting your exhaust flows, which in turn causes, your engine to work harder. So, how can you tell without a doubt that your converter is bad? Well, most any muffler shop can take pressure readings from before and after your converter to ascertain how much blockage exists. Newer style converters can easily be diagnosed with sharp rapping on the underside of the unit. Replacement converters have a honeycomb interior construction and when worn, this honeycomb breaks into pieces and will rattle on the inside of the converter. When you decide to replace your converter, here is a very important hint. There are several replacement converters out there on the market, from the relatively inexpensive universal type to the all out racing style, both of which are smaller than the original stock units. Either way you go, be sure to ask your installer to nestle that baby as far to the driver's side as possible by making a small extension pipe on the passenger side. With the additional access space you get, you will thank yourself later when it comes time to replace that starter or A/C Compressor; believe you me!