so my mom has a 2001 ford taurus dohc. also some newer buick. well the buick was totaled a cpl weeks ago with only liability and it was her fault. she was not hurt though. so i ask her about the taurus. she says my step gpa let some kid work on it. after countless attempts i couldnt get ahold of him. i knew where it was and went and pulled it onto a trailer and did my own repo. get it home to find **** missing and layin all over. first thing is plugs and wires layin in the seat, no battery,and no air box, and no front cat or o2 sensors. finally got ahold of the punk and got everything but the cat(of course he wouldnt meet me and had his lil 18 yr old bro do it). picked one up on ebay. he tells me the cat was getting red hot thats why he pulled it. put the new one on and still getting rewd hot. pulled off the very back converter to hollow and put back in. i just assumed it was plugged. started up and front 2 cats still get red hot. i hear that a non firing cylinder will fill the cats with gas and burn there instead of in the cylinder. thats what causes the red hot. is this true? its not showing a check engine light. will a code reader still pick up a misfire or does there have to be a check engine light on? any help would be appreciated. that punkbeat my mom for 450$ and didnt do **** but tweek out on it. she doesnt have much money and i dont want to start just throwin parts at it cause im footin some of the bill. any advice would be greatly appreciated. i cant wait to run into this punk.

Timming might influence the heat in cats.

But if its not throwing check engine light those odb reader wont pick up anything.

it should have codes stored on computer, light goes out sometimes when battery is pulled.

You you have a good one it would pick it up.

Thanks for the feedback fellas. . I can't really take it anywhere cause the cats get so hot that I worry it will burn something. I'm goin to try to get my hands on a reader. Does anybody have a suggestion on a descent fiarly cheap reader?  Im thinkin I may just buy one. I just get tired of throwing parts at cars and hoping that is the fix. I may also just pay the $80 bucks to have it diagnosed at a shop and I will do the work. Idk. It will habe to wait til the weekend.

so i checked the intake for leaks. sure enough there was. pulled intake off. find out its still got the back 3 factory plugs and wires. changed all them and fired right up. cats dont get hot now!! only thing is that it idles at about 1100 to 1200 rpm. shouldnt it be around 900 or so? im thinkin vac leak or tps? what do u guys think. oh and thanks for the pointers guys

First, If you pulled the upper intake plenumn, They have preformed "o" ring style gaskets, the other common intake leak on the DOHC motor is the PCV hose assy. It's very hard to hear a vacuum leak on these motors because they have a plastic upper plenumn and we call it a loud intake, meaning they all sound like an intake leak because they are noisy and sound like a vacuum leak.
Was it misfiring? another issue that Fords had was an injector staying open, dumping fuel into the intake.
One trick to see if the injectors are firing, take a long screwdriver and hold one end to the injector and the other end to your ear, you should hear an amplified "ticking" noise...if not you have a shorted fuel injector.