F250 running like shit!

[BigOlPig]

Okay my dad has a 93 f250 with a 460 EFI. It has been acting up lately, once the truck warms up it starts to miss and backfire and basicly just run like shit!We checked the o2 sensor and its good..uhmm all the injectors were just cleaned about a month ago, new fuel filter..(put in tonight) after we put in the new filter it ran good for about 30 mins and then it ran like shit after. We took it out..dumped the gas and the gas looked fine. If anyone has any ideas or has had this happend to them let me know, help would be aprciated.

[JJS]

sounds like your ecu may be junk.

[BigOlPig]

ecus fine, we reset it and stil the same. i think the cat might be clogged.//right before this happend the cat gaskets blew for some reason and then it starte to run like ass. Any idea how to unclogg int? or how i can gutt it.

[JJS]

ecus fine, we reset it and stil the same. i think the cat might be clogged.//right before this happend the cat gaskets blew for some reason and then it starte to run like ass. Any idea how to unclogg int? or how i can gutt it.

you can gut it by removing the "brick" inside the cat. once it's clogged, the inner element is junk. my buddy had this problem in a cherokee a few months ago, and it ended up being a junk ecu.

[BigOlPig]

How do i get this"brick" out?

[rabidranger]

Cut bottom off cat, remove brick, reweld cat closed. Or just remove the cat, plug the air pump line (or remove the air pump altogether) and weld in a straight pipe.

[demonranger]

How do i get this"brick" out?

Remove cat get 1/2" iron pipe about 2-3' long big hammer start beating it until you punch through and repeat until all is knocked out.

I recommend removing the cat from the truck first and holding it upright on a 2X6 or something like that while busting out the guts.


IF the cat is Clogged you have some other problem causing the truck to run rich in the first place. The cats on that truck were designed to run 100k+ and if the engine is running correctly you will never need to replace it.

[BigOlPig]

Hey guys thanks for the ideas, we will be trying them soon.I am more so thinking of just welding in a straight pipe. How much louder would it get guys? any ideas? any the air flow tubes is tehre anyway i can just unplug the airpump so it doesnt work? Thanks for your help!!

[murrow68]

It will be a lot louder. If you don't want it to be so loud you can cut the flanges off the cat and weld them onto a cherry bomb or glass pack. I removed the cat on my dodge and it was to loud for me to handle. It isn't so much the noise but the resenation once you remove it. But that is up to you as far as that goes.

[BigOlPig]

Cool, well were gonna take a look today,see if we can find a pipe that goes 2-into one. Thanks alot guys, verry aprciated..im sooo hoping this is the problem
Jon

[chrono4]

have you pulled the codes?

[BigOlPig]

Pull the codes? the check engine lights not on what do you mean.

[n9emz]

My 95 F-250 w/5.8 EFI started running crappy and it was an oxygen sensor. $80 part. If codes won't come up, pull a plug wire to bring up the check engine light and then run the codes. All that work for the plugged cat? Go true duals. A couple of places locally do it for under $200 and it really makes a difference. Good luck.

[BigOlPig]

Yea we'd goo true duals, just cant afford it right now, eventualy well throw some headers and flowmasters on there..jsut need the cash and it running good first:P

[PONY_DRIVER]

The CEL does not have to be on to pull a code as not all codes trip the CEL.

[n9emz]

The CEL does not have to be on to pull a code as not all codes trip the CEL.

True, but pulling a plugwire affects mixture, exhaust gasses, TPS and other components which may cause a defective item to code out that previously wouldn't. Several problem components acting in concert that are within margin can radically affect performance yet not code.

This is not a common problem with Fords, but a possibility....somewhat along the lines of the GM "random missfire" syndrome. You could spend a grand replacing parts and still not cure the missfire; but, pull a plugwire and you might then get a "coil cyl #8" code.

Hope this is of some help.

[f250crawler]

I had my cat in my 89 f250 clog up, it wouldnt go past 15 miles an hour, soi cut the cat off, and it is loud, if youve ever been to a drag race it will sound familiar. if u replace the cat though make sure you get the right one see if you have two air inlets or one. The price for the dual air inlet cat is around 500 just for the cat, and about 200 if you have the single air inlet. scrap the whole exhaust and just put on a new cat, and run 3 inch single pipe and it will run better then new.

[NetBSD]

i never ran a cat as my truck doesnt need one for inspection but i agree with 1/2 the board, weld in stright pipe on some cherry bombs or glass packs, im currently running 2 1/2" stright pipe dual cherry bombs on my 78 f150 400m and she runs mean, a lil rich but mean :flipoff2:

[BarrelRoll]

Do 460's have an ignition moduel like a 300, i know mine went bad and it ran like shit, the back was coroded and would heat up and not ground right.