Hello,

Got a question about replacing the cats in my truck.

1999 F150 V8 5.4
Trans Code U - 4R70W
4WD

background

I had my truck at Ford the other day as I tend to like my local dealership's service department. I had them check out the truck (during an oil change coupon offer) for potential issues due to a road trip I am taking next week with my trailer. I mentioned I wanted the exhaust leak checked out. They found the leak which was located in the area of the Cats. I went into the shop and physically saw for myself the rot. The service adviser said he it would be better to have a muffler shop replace the cats as Ford would not be competitive. We went over a few other things that needed attention and I authorized the repairs so there would be no issues for the drive. The mechanic mentioned to me in the bay the truck was one of the better ones for that age range and can see that it is maintained regularly.

So I am looking up cats for this truck. It seems the cats in stock are for 4R100 trans. I called a few auto parts stores from the big chains to local guys. Everyone asks "Are you sure you don't have a 4R100 trans?" One place said they didn't have a listing for my trans for that model year. One place found them and quoted me about 70% above the cost of what I can find for the 4R100. From my understanding the 4R70W seems to be a pretty common trans like a 5.4 V8.

At this point, am I better off just finding a "good muffler shop" to replace the cats? Also would I not see a code being thrown by the O2 sensor if there was leak in the cats? I have no codes or CELs. The truck runs great and gets descent gas mileage. I just can't stand the leak noise since it is in the cab area. Like I say, performance sound by mother nature!

Please give me an idea of what direction I should investigate. Thanks in advance.

 

Is it something that can be welded or do they need to be replaced?

 

Simple answer, I don't know. The holes appeared to be towards the top side of the cat. I used the mechanic's mirror to view the rot. I would not be surprised the pipes are rotted out as well. I recently replaced the muffler and tailpipe. To be welded, they would have to be dropped to get to the spot in question. The one thing I do know, you cannot weld rot

If it is costly, I may just live with the noise for awhile and work my way to getting it fixed at a later time.

 

Other members have bought the cats online and had muffler shops install them and taken the old cats into the recycler and it nearly pays for the whole deal. Go with the magniflow universal single cat replacement. Look over at summits web site. Replace them both. Should improve performance while your at it..

 

If you want it done right without paying a small fortune, take it to a good muffler shop. The Ford adviser was being honest - for them to replace the cats would probably run you $1600.

 

Look everythng over good.
If there are other places not looking to good you will be back there again soon doing it over again.
A cat assembly for one side is about $300 after market boltin.
There can be issues getting the head pipe to manifold apart with out breaking bolts so it has to be done carefully.
If you go with a whole cat assembly, cut the old one out with a torch so you can work on the manifold bolts without any extra hassle.
Been there. Good luck.

 

I will look for single cats but everything I have found is 2 cats a side. Each part ranges about 250-350 depending on the side plus new hardware and probably some new pipe to the muffler. So top end estimate on parts is 700 to begin with plus labor. I found Walker builds which was 300 driver side and 350 passager side plus hardware, pipe and shipping.

or

Are you talking about getting 2 universal cats and have one of cat on each side deleted?


I don't know if I want to mess with this one. As for bringing the cats to recycling. I am all for that


I am thinking about finding a muffler shop after my trip. I replaced a cat in my Bronco back in the day and it was single universal design. Took a couple of hours I think don't remember. This particular service adviser treats me pretty decent plus it helps to have some history as well. My father was involved with the Windstar rear axle recall a couple of years ago. He is on a first name basis with the service manager who will actually come over and talk with my dad when he comes in for service checks due to that recall. Honestly, I do not know the details of my parent's minivan but whatever transpired I became a benefactor of it. I digress.


Thank you for your experience and advice.


I think I will sit on it proverbially speaking until the cats fail. I cannot see spending the money for the noise currently generated.

 

I've been getting P0430 and suddenly P0420 the other day after my 94106 high flow install 2 years ago. Becareful guys. Magnaflow is all over the place. I have been to 2 shops now and they can't find any leaks. The one I went to today said Magnaflow had quality issues about 2-3 years ago with their universal cats. Apparantly the catalyst wasn't up to the standards that a lot of the engines were requiring and they would destroy the cats. He said they came out with a heavy metal (you'll see HM on the end of the part #) to remedy this and it has more catalyst in the cat to filter like oem. Now I don't know how true that is, but he also said the 94106's are OBDI and he showed me the Magnaflow catalog and they do say OBDI. I looked online; sure enough, OBDI. yet the boxes I had them in said OBDII? Their site lists the universal for our trucks as a 2.25" in/out (I think it was 51355 or something like that) cat which makes no sense. Needless to say I'm not sure what to do at this point. I'm gonna get in touch with the high end performance shop and if the can't figure it out, I'm gonna have to order the direct fit type and be done with this. It's really aggravating. If I do that I'll have to get a real small muffler to make up the sound difference. It sucks.

 

And what about this? When people delete their rear cats... is that better and no chance at a cel or is it too smelly? Cause I could just get the oem replacement style, right?

 

Link

 

Magnaflow website shows specific part numbers for 4.6 2wd, 5.4 2wd, 4.6 4wd and 5.4 4wd.
Front and rears are also different part numbers and have all been changes to the 4xxxxx series for OBDII.
If a vehichle is in CA, the assembly must be replaced as a complete unit to be legal for mounting position, ID numbers and all. The law is a bit crazy but that's what Ca. does.
See the CA law on all this.
The code 420 is bank 1, 430 is bank 2.
Both are failing in about the same time interval.
Be wise to look at the activity of the rear sensor on both sides to verify the codes.
Also consider if anything was done to kill them such as the use of fuel additives etc.
Good luck.

 

I think I'm gonna get a set of the direct fit magnaflow 49 state ones great prices on Amazon and some NBA cat4ward headers to gain some sound back.

 

I got a set of Maggies for my truck when it had a running rich problem. I paid $60/each for them and took it to a muffler shop. I paid $250 for him to cut out the old rears and weld in the news. He welded the new ones upside down (idiot) and didnt even give me the old ones back.

engine/exhaust sounds the same, no performance gain (that i could tell).