1998 F150XL SC SHORTBED 4X2 4.2 V6 4SPD AUTO
78,000 miles stock except for the "dual" exhaust.
16-17 mpg.

Got it from my Dad last month. He had a "dual"system put on by a shop he uses. bugger is rusting out on the chrome tips and sounds like a school bus. Drones like crazy on the open road. No bottom end, but seems to pull fine when the revs are up. The engine light indicates a lean condition on bank one and bak two. It came on the second day I had it. My mech replace two O2 sensors and the light went off then came back on that night. it now has a shudder on idle.

Muffler looks to be some sort of tubular glasspack thing and has smooth, rounded ends with no markings. After the outlet is a Y connection that splits to the dual tips coming out under the bumper. On the inlet side of the muffler, there is an expansion adapter that flares into the inlet. Pipes look to be 2.5 inch. We suspect the muffler has blown out it's packing and is contributing to the lean condition.

I have purchased from my local Carquest, a Vortex system from the cat back. It is a 3 inch single system. $185.00 which is fine as I'm not building a show truck for now and am looking to get the nasty mess that's on there off.

So, the question is: Will I get the bottom end back and do you think this will help with the lean condition we are hunting down?

 

if it's a glasspack, it may likely be the problem. if it's broken, or blocking the exhuast, hell yeah that'll make it run like crap.
could be a blocked or broken cat too. i shattered the cone in one of my caats on my old ford and it shuttered at idle a LOT. took the cat off and replaced it with a high flow and it ran like a raped ape.

you've alreaday got it ordered so i guess you'll find out if it fixed it!

 

3" single might be a tad large for the 4.2, but, IMO, it'll be better then the setup you have now...... I'd think a single 2.5" system would be best for "low end" on a 4.2....

The trade off in "all out HP" and "low end" is that you can't go too big on the pipe size..... For low end, you need to keep the pipes kinda small.... But that hurts the high end..... Get big pipes and it'll be a screamer at 5000 rpms, but the low end will suck!

There's debate on what backpressure does to a system and I don't claim to know anything about it, but from my own experience with my setup, I can say, the muffler itself makes a BIG difference in any exhaust system.....

I'm probably not the best judge of what's best for the 4.2, as I have the 5.4, but for what I use my truck for, LOW END is all I want!

With the stock setup, I could barely get a scratch out of the stock (bald) 235/70/16 tires. I replaced the tires with 255/70/16 tires and it was even worse! I then got a K&N drop in and a 3" Gibson single exhaust setup. I could now get the tires to scratch again, and it seemed to have better throttle response. 30 days later, I decided the 255's were still too small and got some 265/75/16 tires! Oh, that made a difference in the looks, but now I was back to square one again (could not scratch the tires and it kinda bogged on the hills now).

I then picked up the travel trailer in my sig and it towed ok, but still downshifted alot on the hills.... After a couple of tows the Gibson muffler developed a rattle, so I got that replaced with a Flo-Pro.... OMG, what a difference that made! I still had the same K&N and the same 3" Gibson tailpipe, but my low end seemed to increase a whole lot! I could actually SPIN the big 265's and on hills that would bog me down to the point of downshifting, I could now cruise up them in third! Towing was the same deal...... Where the truck would bog down, I could now maintain speed and stay in third gear! I'm talking LOCKED third too!

I've still got the stock Y pipe setup, and was all ready to swap it out for the Flowmaster one, but when I took it to my muffler guy to install, he said it would "kill" my low end and probably set off the CEL...... Well, since he basically talked himself out of a $50 welding job, I figured he knew what he was talking about....... I've been very satisfied with the trucks low end and to date, no CEL..... Other's have said they gained low end with the replacement of the stock Y pipe, so I guess it's just up to you what you do and "your results may vary"!!

That's my story, so take it for what it's worth (it was free for you) and compare it to other stories you are likely to hear and go from there!

Good luck!

Mitch

 

Mitch- I have a '97 F150 4x4 w/ 4.6L. I was courious as to which Pro Flo muffler you got. I looked at their site
http://www.flopro.com/FloPro.htm
and there were numerous types there. I would like to try the one you have. I am planning on installing 285 size tires and I want to improve my low end. Thanks !

 

I got the MX502. Oval, offset/center.

On mine, the muffler guy put the center as the inlet and offset as the outlet. He left the 2.5" inlet to match the existing 2.5" pipe coming off the Y pipe. He then also left the 2.5" section of outlet pipe and placed the 3" tailpipe over this...... He said it'll create a kind of "chamber" where the pressure will be different and that'll help keep the cab drone down and it should help with additional low end power.....

I don't know about all of that, but it does have more low end now then before! It also sounds a lot better then the Gibson ever did! Not loud at all, but that good ol' V8 rumble that lets you know it's not a vacuum cleaner!

Even towing, the sound is not that loud in the cab. At least the wife does not complain! And she would if it did too!

Mitch

 

Well, the new system is being installed this morning. Should be done by noon Eastern time. best guy in town is doing it and said it would be about 40 bucks.

I've got some driving to do this evening so I'll know by then if we've had a successful operation.

Question: Will the CEL have to be reset or will an effective repair take care of it and snuff that puppy out?

 

Dang! I wish I could get the 71 mpg that you do!!!

 

"Dang! I wish I could get the 71 mpg that you do!!! "

Man! I been doing that a lot, lately.:o Whoopsie!
I changed it. Thanks!

Anyhoo, I picked up the truck at noon. results are more growl, less drone. Seems to be a bit stronger across the board with more bottom end. A little bit quieter without that head pounding school bus drone.

Mech said it was for sure a glasspack and the setup was just darn ugly and poor workmanship. He was able to pull the whole thing off in one piece. Nasty lookin's mess.

CEL is of course still on so I'll reset it tonight by unhooking the battery. See what happens.
next step will be an intake setup and one of them fancy programmer thingies. Once the CEL problem is solved, of course.

I'll report back tomorrow with any mpg changes, etc.

 

lol I thought you did it on purpose! Gave me a good laugh!

 

OK.

Still at 16-17 mpg.

Exhaust sounds good and I can tell once we get the CEL problem tracked down, this will have been a good choice over the previous system. I can feel it really wanting to let lose and seems to be getting a bit stronger the more I run it.

Pop drove the truck for about 50,000 miles and rarely got over 60 mph.

Current symptoms are a surging at idle with shudder in drive with brake holding. occasional sprak knock and almost a dieseling just as I hit the throttle to move out. That seems to have cleared mostly.

Fuel filter was replaced earlier this past year, but I'm wondering since Pop rarely put more than a couple gallons at a time and I fill it up each time, migh be he picked up some crap in the system. could aslo be an egr thing since he drove it like it was gonna break. Drving the heck out of it, running back and forth hauling stuff for the house remodel.

Gotta fix this CEL. The hunt begins......