I have a 1991 ranger with a 4.0 I was wondering if it is suposed to have two catalytic converters on the single pipe and if it matters if i gut them.the truck has a single glass pack muffler and a y pipe after that with duels and i would like a little more sound out the back because it still sounds like a grandpa truck.

 

My '91 had the same 2 converter setup. I cut them off, welded in a section of pipe, and never looked back. The truck is slightly louder without them but not bad. I have the stock muffler though.

Technically you are supposed to keep the cats in place but as long as they do not do emissions testing in your area you will be fine. Chances are that the converters arent doing much anyways since they are so old. My truck even seemed to run a little better after I removed them.

 

Johncfox:Chances are that the converters arent doing much anyways since they are so old.

And just what authority do you cite for this??? Do you know what the word catalyst means? If you don't kill it, a catalyst will outlast the rest of the vehicle. Read up a bit before you opine... They can still be good after 250,000 miles, as a catalyst is not consumed in the reaction it promotes.

tom

 

Agreed, my dad has vehicles with much higher mileage than that with the original catalysts still working perfectly. Mileage doesn't kill catalytic converters, ignorance does. If you keep the engine properly maintained (meaning you don't just change the oil and replace stuff when it breaks) then the cats will outlast the 20+ year life of the chassis. They can still be good with over 1 million miles. To an average driver, that is one hundred years of driving to and from work each day.

Properly functioning cats are induction devices, which means when they are warmed up, they assist the scavenging process to remove as much spent exhaust from the cylinders as possible. So a car with a properly functioning catalyst should produce more low end torque and get better gas mileage than a car without one.

 

When I first read this I thought "What a bunch of Taurus poo! " I thought the piston on the upstroke removed as much spent exhaust from the cylinders as possible.

 

Who took a poo in your cheerios? As a matter of fact I am well aware of the meaning of the word catalyst. As a mechanic I have repaired the emissions control equipment on numerous vehicles.

The converter housings have a habit of rusting out ESPECIALLY on ford rangers for some reason. The converters used on many older fords also have a problem with breaking apart internally. A busted and rattling converter isnt of much use. A properly maintained engine can help a converter last a long time but they do not last forever. The catalyst can wear out over time. I have replaced dozens of converters on vehicles due to the catalyst being below minimum efficiency. The only reason downstream oxygen sensors are used is to monitor the converter and throw a code when it fails. Even if the honeycomb looks intact it can still fail to perform properly.


Also btw the authorities I cite are the guys at Cotaco Creek Converters here in north AL. They are one of the leading recyclers and remanufacturers of catalytic converters in the USA. I have had several conversations with them on this subject and said my assumptions were correct. Then again who do I believe, the professionals who are licensed by the Epa or some idiot on the internet?


On some vehicles the converter is large enough that it does not restrict exhaust flow. When it is, you can have better performance and mileage as a result of the increased exhaust scavenging due to the chemical reactions. However on many vehicles the converter is the bottleneck due to small honeycomb and outlet pipe size. If you modify the engine at all it will make the restriction even more apparent as it will try to push even more air through the converter.


Believe me or not, I dont care. I am tired of typing. The original poster simply asked whether or not gutting the cats would increase the sound of the truck. It will, plain and simple.

 

jcf: Read what I said. Converters do not die, they are killed. Period. Your stories about whether a converter works or not come from someone who has a buck riding on the myth that they wear out. If they wear out, how can you 'remanufacture' them? SOMETHING in the vehicle killed those converters that died.

Blanket statements, such as the one you made, will sell to some, but not to me.

Your comment about breakfast foods is rude and childish.

I have a vehicle about to reach the moon in mileage, and the original converter still works. as does the one in my Ranger that is 25 years old.

Have a nice day.

 

Not to be rude, but your statements prove that you don't know as much about converters as you think you do. For example, your statement that they do wear out referring to the P0420 or P0430 code catalyst efficiency below threshold. I bet you have to warranty a lot of converters because
you are assuming that the converter has just failed because it wore out. It has failed because the vehicle is running too rich or to lean and has either overheated the catalyst or has coated it with carbon. Those two conditions reduce the effectiveness of the catalyst, and it was not the converters fault. It did not wear out, it was destroyed. All it takes to prevent this is a little maintenance. The owner just has to have a tune up at regular intervals, and to replace the O2 sensors before they completely fail. The manufacturer recommend at 60K - 80K miles. If you replace them before they fail, you ensure the computer gets accurate information, and that improves gas mileage, and helps ensure that the vehicle doesn't run rich. If you look at these cars that have bad converters, most of them are still running the original spark plugs. As I stated earlier, mileage doesn't kill the converters, ignorance about maintenance does.

Your statement about earlier Ford breaking apart is also not really true for Rangers. Any converter can break apart, but most are related to overheating, and defective OE designs. The large converters used on the 3/4 ton and larger often failed due to a combination of defective design and bad thermostats. These problems are not found in the Ranger.

The guys at Cataco Creek build low quality junk, and most of the stuff I have bought from them failed. i have spoken with them before, and its not just them, the entire remanufactured converter industry is stuck in the stone age. They use outdated test equipment, the test procedures are outdated, and they sell a lot of units that marginally passed their test, units that don't work in the real world. I have sold many remanufactured cats, and I know form experience that the track record or remans is abysmally poor. Some units have warranty return rates as high a 4 out of 5. I only buy remans when there are not aftermarket alternatives.

The biggest performance bottleneck on most cars is the muffler, followed by the stock manifold, with the poorly made y-pipes and the converter being a close tie. As the cars get newer, the converters become part of the total performance package. Most newer cars will not run properly without them.

To the original post, your truck is old enough that the converter was not part of the fuel management system. It is more of an afterthought. It probably doesn't flow the best, partly because it is too large. If you want to eliminate it for more sound and performance, don't gut the old cat out. Do it properly at replace it with a piece of pipe. A hollow can acts as a turbulent expansion chamber that catches and slows the exhaust coming out, robing potential power.