I have a 2001 Mustang V6. I lost the catalectic converters in it, and cannot come up with $1500 to replace them. So I had my exhaust guy simply gut them out. Well that worked on our Jeeps, and on my S-10, however on the Mustang it is not working. It sounds like crap, and is eating fuel like you would not believe. We are not sure what the exact problem is. I know that it has an 02 sensor that reads the exhaust and will change the a/f ration, but that is supposed to trip the Engine idiot light. That is not on. Does anyone know if that could be the problem with out hitting the idiot light, or is it maybe too much back pressure that can be fixed by running straight pipe??? Help, I want to drive my car again.....

 

Some trucks have to have the computer reprogrammed or flashed to recognize the change, some have tweek boxes you can plug in, I had to put new O2 sensors in my truck when I did it and all was well.

 

How many miles on your car? If less than (I think) 80k, there is a federally mandated warranty on emissions which would include catcons.

You should have O2 sensor in front of the cat con and one after it. The one after it is reading way out of its parameters since the honeycomb has been gutted out. More than likely it is causing the computer to default to full rich mode which would account for the poor fuel mileage.

If that is the case, I have a guy up here in Salem that might be able to help. PM me.

I don't know if your fuel mileage started to drop off before the catcons failed but it can be the proverbial chicken or egg. If you have some other problem that defaults the computer to full rich, it won't take very long for that to melt the catcons down and plug them up. You will want to plug a diagnostics computer into the car to make sure you don't have any other codes or fixing catcons won't help. You will just take them out again.

When are you up for emissions testing again?

Ron

 

CA emmission laws are really crappy and is the biggest problem in all of this. The car has 110,000 miles on it now, so none of that will work. The car ran perfect up till it plugged up the eshaust. Crash has been talking to people that race them in Sac, and they said if it were running rich because of the 02, then the engin light should be on.....I know there are performance pipes and such out there that I could get to gain alomst 20hp and the only state they won't pass is CA. And the next emmission test is the problem....It is due this coming Oct.

 

I recently experimented with my race car ('96 corvette) on exactly what you did. I had one cat that had broken up a bit, so I hollowed both of them out to see if I would get a performance gain. Based on testing before and after, I actually lost performance. In theory, the oxygen sensor was reading inproperly because of the missing cat and was telling the ECU the wrong info. Since the ECU had the wrong info, it delivered the wrong amount of fuel. Based on the info the ECU is getting, there is nothing wrong so it will not trip a check engine light. I put new (used) cats back in and got my performance back(13.5 at 105MPH- it's an SCCA Solo car, not a drag racer).

Your best off putting the cat(s) back in. Check a junk yard for replacements, or look on line for replacements. Since your car is 5 years old, you can install aftermarket cats that are cheaper and flow better than stock. They will cost a bit more to install because they have to be welded into place. You can get OEM style, bolt in cats, on-line for less than 1/3 what dealers want for new ones. Some states don't allow junk yards to sell used emisions equipment, so if you go that route, tell them you want the "exhaust", not just the cat.

 

As a side note, my '96 Dodge truck recently plugged up the cat. Strange thing though, about two months prior I had recieved a letter from Dodge saying that they were extending the warranty to 100,000 miles (my truck has 154,000) or untill the end of '06, what ever is later. It felt strange getting warranty work done on that old of a truck, but they did it with no hassles.

 

check to see if you have OBD1or2 (onboard diognostics) on your car... it will say on the tune-up sticker under the hood..
if you do, the car has 4 O2 sensers .. one on each side of the convertors.. maybe more.. if you hollowed out the conv.
chances are the O2 sensers arnt geting hot enough to work right.. and there going lean and telling the ecu to go full rich....
if you dont have OBD 1or2... the O2 could still be driving it rich, and the check engine is not coming on.. the old systems
didnt always work the best ...
just a thought......

 

You might try something simple like jsut resetting the cars computer. I believe if you disconect your battery, just the ground is fine, and then turn your key on for a minute or so, then reconnect your battery. This should reset your computer and let it relearn with the cats missing. It can take up to 250 miles or so to fully get is settings.

Worth a shot, and its free...

 

Well a little update on the car. It appears we have her running for now. Picked up some M.I.L. Eliminators, and threw those on to trick then 02 scensors. We had to reset the computer, and she seems to be running alright now. Sounds pretty good with the Cats gutted out, and a flow master on the end. I am going to through a K&N filter in her next weekend, and having a performance chip from a 94 Ranger reprogrammed and going to get thet on in the next week or so. Then a full X-pipe exhaust, and ......... Crap, I was being so good and only adding things to my quad. Now the bug has a hold of me on the stang also. I need another job, or 2 or 3......Grrrrrr