[1996thunderchicken]

ok now i have a question on this because i have excessive heat comming from the bottom of the thunderbird and i think my cats might be getting cloged cause when driving when it hits third gear it starts to rattle and wants to jerk unless i let off the gas or hit it and when i have it kept at 30 mph and let off the engine will rev up a little but instantly go down but also i keep being told to keep the cats or i will lose power and run like crap and lose gas milage but i was also told to watch out on the cats cause they can catch fire and i dont like the sound of that cause i have my daughter in this car every day i could care less about my self.i am just wandering y would they sell non cated x pipes for my ap if all of this true so i am confused please help

[timothale]

Usually a check engine will come on When you start having ploblems. If you remove the cats for racing you will have to change other parts , reprogram the computer, mabe change to bigger injectore etc ,etc. Most info on this site is for GM products, you probably can find more on a FORD site.

[curtis73]

Replacing them isn't too expensive. You can get the universal ones for about $200 each and then have a shop put them in... probably another $150.

You'll see all kinds of labels on them that say "not for use on 96-up OBD2 vehicles" but just ignore it.

[cleanspeed1]

Keep the catalytic convertors and replace them. After a ton of miles, they do clog up, especially if the engine was neglected as far as tune ups and maintenance, and a lot of stop and go driving where the engine is not running at operating temp consistently and constantly ( highway driving ).

Sounds like there is more going on with the engine than just the cats. Cats only overheat when the engine is running rich all the time.

Has the motor been completely tuned up with all sensors operating properly?

Have you changed the fuel filter lately?

Have the O2 sensors been replaced?

How many miles do you have on the car?

[1996thunderchicken]

the engine i know needs a lil tlc the guy that we bought the car off of said he had replaced the plugs and plug wires i did have to replace one cause of a complete missfire caused by an intake leak from the heater hose nipple at the back of the intake i still have to replace the intake and no shop cost to me i do all my own work im just kind of curious about this i know i can get the mil eliminators from all american muscle that deletes the two down stream o2 sensors what other computer reprogramming would i have to do

[DoubleVision]

I sure know cats get hot and fast as I just replaced the oxygen sensors on my parents `05 mercury grand m. The engine ran a total of 2 minutes so I could put it on the ramps, when I got under the car they were already too hot to operate around. Anyways, if the car goes to jerking it`s not likely the cat converters, it sounds like the EGR isn`t working.

[sbchevfreak]

Cats can cause a "jerking" type of symptom, especially if the substrate has come loose from the converter body. It can move inside the shell, and momentarily restrict the exaughst enough to cause the engine to bog, reducing flow in the exaughst. When the flow drops, the substrate drops back into place, and the flow increases, starting the whole thing over again. This usually only happens on badly failed cats, though. Easy way to tell for plugged cats, is to drill a 3/16" hole upstream of the cat, start the car and stick your vacuum/fuel pressure guage hose on the hole. If you see anything more than 1.5 psi, the cats are getting plugged.

[LATECH]

He said he is still chasing a missfire, one that he says is caused by a supposed intake leak. The jerking he is talking about is most likely why there is a missfire code generated, probably not EGR or Cats, causing it. I doubt an intake leak is causing it either as it wouldnt be intermittent.I would adress the ignition system and check the injector, possibly move an injector to another location to see if the misfire goes with it to the new cylinder that the injector is put into.Quickest way I know to make that determination as the injector could ohm out OK but still malfunction.
I think at this point it should have the misfire issue addressed and repaired, whatever is causing it, then scan live data to check fuel trim and for any discrepencies in the system, then perform a backpressure test to determine if the cats are plugged. It is so simple to do. Just unscrew the upstream O2 sensor and put a combi gauge you know pressure -vacuum...in the fitting and start the engine. Wack the throttle open and bring it to 3000 rpm abruptly. If the pressure is over 1 pound they are plugging or are plugged.
I had one here a while back I tested that way, the drivers side was plugged and the passenger side was flowing freely.
I marked it with a skull and crossbones for the muffler guy, so he wouldnt get confused when he changed it.
In extreme situations you can also lower the crossover pipe at the manifold and see if the performance problem dissapears as a result, it is quick and usually easy to do. It is a good presumptive, the gauge will get to the nitty gritty though.

[LATECH]

This is the gauge I am refering to.A fitting or two and it will screw into the bung where the O2 sensor goes.
I had one for years. I had to replace my old one last year after it dissapeared. I had to go to harbour freight for it.

[1996thunderchicken]

well i cant seem to get it to hit the 3000 rpm quickly i have to put my foot into it for a few seconds to get above 2500 rpm but im kinda thinking i might have a fuel pump going bad it seems like its starving it self going down the road cause when it stalls its at the 3rd to 4th gear change and usually i give a good punch to the petal and it will come out of it but it still has that rattle like the heat sheilds are loose and i will smell a gas and i went over my lines none are leaking and also if i want to get going quickly from being completely stoped it takes a few seconds and then it kicks in like after 20 mph and i have my foot to the floor but no backfire issues or overheating wouldnt my engine overheat if the cats were bad

[badknuckles]

No, your cat might overheat though. Look to see if you can get it glowing.

[badknuckles]

A misfire will cause a bad cat if not corrected

[1996thunderchicken]

i corrected the missfire with an iridium autolite plug but it had been missfireing for a couple of months before we got the car but i dont know caues i was looking underneath the car yesterday after running it all day no glowing from the cat