98 f250 LD running rich cause of magnaflow
 

Hey, I bought this truck recently with a magnaflow on it.. the truck seemed sluggish and i couldnt figure it out till i realized that the exhaust could have been the problem.. i talked to my auto teacher (huge dodge fan..) he said a programmer might solve that but he doesnt know much about programmers avalible for this year/model

Anyone have an idea of the easiest, cheapest and best way i can fix this problem without going back to the stock exhaust?

the truck also has a K&N air filter.. if that makes a difference but im pretty sure it doesnt affect much.

the k&n probably muffed up the MAF like they always do. exhaust wont make it run rich or lean.

so would i be better off to go back to the OEM filter?

you could try cleaning the maf with CRC maf cleaner and make sur eyou don't put to much oil on the filter. I think the oil messes with the MAF

Not an exhaust problem. My '99 F250LD 5.4 3.73 has a 40-series Flowmaster in place of the stock muffler with no change. It's either sluggish due to other issues (as mentioned), or is just naturally a slug. The 5.4 in these trucks are going to win any drag races.

First, how did you determine the motor is running rich?
How did you determine the truck is sluggish, just owning it a short time?

The OX sensors control the fuel injection.
They are located in the pipes before the cats.
The muffler is after the cats and has no influence unless blocked or restricted.
As for the K&N, remove it and replace with a stock element.
Under "normal" "non performance use" it offers no advantage over the stock type elements for performance.
The air meter could be coated with element oil.

my uncle ownes a 2002 ford with the 5.4 and it pulls alot harder than mine.. it could be because of the extra weight of the 250ld vs the f150 or it truly could be an issue..

as the problem of the truck running rich, there is strong fuel smell in the exhaust.. im not familiar with fuel injected engines because most of my experience is with dirtbikes, atv's and snowmobiles (carburated) but i can tell it is running rich.

The '02 also has a good 30 more hp.

Your going to have the re-examine your thinking about modern computer control.
There is no 'control' compairison between a carbed motor and computer control as far as total operation and control of fuel.
Unless there is a system problem, you cannot tell richness in the exhaust that would be noticable under normal operation.
Fact: if you look at spark plugs in an FI engine that has no issues, you would see them as looking a bit whitish such that you might judge the motor to be running lean when the fact is, it is normal.
The fact of it is the computer takes feedback from the OX sensors that keeps the A/F ratio very close to an average of 14.6 to 1 in ratio under normal driving for each cylinder as they come up in there fire order. Only when throttles of about 7/8 or greater will the fuel ratio go to the 12 to 1 range to satify the motor for power. At this time the normal fuel table access is switched to a more fixed richer fuel table to fuel the motor.
The tables control the "time on" or pulse width of the injectors as the way the amount of fuel is controlled
A carbed motor will not come close to this level of control such that the plugs will look some shade of brown or grey in a normal running carbed motor that normaly in compairison, is a bit over rich.
The above two points between FI and carburation are the big differences on fuel mileage and near instant throttle response for FI.
Bottom line is the PCM controlled motors are so good that the PCM it'self is used as a pass or fail indication in most states without actual tail pipe testing to verify emmisions.
If your truck has no codes set or CEL lighted, the OX sensors are not detecting a rich condition.
Sometimes cats can cause a peticular smell especialy following one up a hill.
In this system, the lack of enough oxygen in the exhaust is the rich condition. What happens if such a condition is detected, the PCM attempts to lean out FI by shifting it's software fuel tables to the lean end. If the shift goes out of limits, a code is set and Lamp lighted to alert you there is an issue.
Be carefull about judging a PCM controlled system based on old tech that you are used to working with.
I also have a good deal of experience with both gas and alky fueled motors as well as super charging.
Good luck..