Here some particulars about my situation..

1997 4.6L 130,000 miles.
Plugs: New
Wires: Less than 1 year old.
Fuel Filter: Less than 1 year old.
Did the EGR port cleanout on the TB.
Replaced DPFE (AutoZone, not dealer part - problem?)


The truck was missing badly prior to the TB cleanout. Disconnected the battery, did the cleanout. Seemed to help.. for a while. Started missing again after 2 days. Then I replaced the DPFE. Ran OK for a day.
Now it's running so badly that my wife is afraid to drive it to work. It misses and so bad that it barely runs.

I had her take it to AutoZone to get codes. The only one that came up is P0141, the O2 sensor after the cat on bank one.

Could this sensor be causing all this trouble? From what I have read here and on other sites, the answer is no. If not, any other ideas?

Thanks...

 

Well you can start with the basics. Check the sparkplugs are they tight? What brand did you install? Are the new wires still making good connection at the coil packs? Did you spray/hose the engine down for any reason, water in plugs? How about the MAF try cleaning it with MAF cleaner. When you reconnected the zip tube to the throttle body, did you get it completely on especially at the bottom? All vacum lines connected? Bank one HEGO code. More than likely the miss is on bank one but not always the HEGO is reacting to what is happening up stream. Is the throttle closing completely, not binding on anything that you reinstalled? Any noises associated with this rough running like ticking, tapping, knocking? Theres a start. Others with will jump in with more ideas. Good luck.

 

I forgot to add that the MAF was replaced with the fuel filter less than a year ago. Other than running horribly, there are no noises, etc.

The engine hasn't been hosed down and all vacuum lines and intake tubes are connected properly. It's pulling approximately 18 inches on vacuum gage at idle.

 

yea, what kind of plugs did you put in?

 

Autolite Platinum. Took out Motorcrafts, and there is zero difference.

I forgot to mention in the original post that when the truck is started from dead cold, it runs fine for about 3 minutes. Once it warms up the problems start.

 

thats a problem right there. put in either a set of motorcrafts or denso plugs and dont forget dielectric grease.
the modular fords are very picky about spark plugs. sometimes they accept autolites but alot of times they dont. the only brands that have so far been proven to work well with them are ngk, motorcrafts, and denso.

 

Was there a reason for changing the MAF ? I take it you have been having some type of problem in the past that made you change it. The MAF is a different animal. I've seen them cause some strange problems and not throw a code. Did you replace the original with an aftermarket? Try cleaning it just for the hell of it. By the way do you have a K&N air cleaner? If so excessive oil from the K&N can contaminate the MAF. Your sparkplugs could be fouled as well, once they start fouling they only get worse and the truck will run like complete ****. Matts right regarding spark plugs. Stick with Motorcraft. Good luck.

 

Here's some history on this truck:

Last spring, it began missing and running rough. It was throwing EGR and misfire codes. I changed the MAF and fuel filter first on a mechanics recommendation. That changed nothing. Then I changed the plugs and wires. I put in Motorcraft plugs. That seemed to solve the problem although it was still throwing EGR codes, it ran decently. The problem resurfaced early this summer, and I assumed the issue was not related to ignition. I found the EGR port cleanout thread and did it. That seemed to help, although it was still missing a little. 3 days later it really began running bad, almost to the point of not being drivable. I put on a new DPFE per forum recommendation. I think it actually got worse after that. I then decided to change the plugs again, thinking they fouled. I pulled out the Motorcrafts and they looked almost pristine. I replaced them with the Autolites. It made absolutely no difference and the only code being thrown right now is the P0141. I have not replaced this sensor yet because I am tired of throwing parts at it and from what I have read, this sensor is not capable of making the truck run this bad.

Could this be an injector problem perhaps?
Coils?

Does the fact that it runs decently when stone cold point to anything in particular?

 

I know this is an older thread, but my 97 F150 (4.6) is having the exact same problem. Plugs, wires, coils all have about 5000 miles on them - plugs are NGK. Throwing same code as his - P0141.

Went from running fine one day to chugging/missing and hesitating the next morning. Problem seems to get worse as the truck warms up. Could this be a clogged cat maybe? Any other opinions?

Thanks for the help!

John T.

 

A P0141 will not affect the way it runs - you have a bad post-cat sensor. All that sensor does is report on cat efficiency. Yes, it's quite possible you do have a clogged cat.

 

The cat was the only thing I could think of that may cause this kind of a problem and not throw any other codes. I just didn't want to start throwing parts/money at this thing without doing a little research first. Anything else it may be that would cause it to run this rough under a load (misses slightly in park, but gets worse when under a load at lower rpm's) ?

Thanks again!

John T.

 

I would start by checking basics. This vintage truck has the sparkplugs that can loosen and come out. Its been 5000 miles since you say you changed them... I would start there by removing the plug boots and checking all the sparkplugs. Coils can also fail and cause a miss especially under a load. Codes don't always showup and are not always accurate.

 

i just turned 300,388 miles!!!!

check engine light came on and got codes for : egr, maf, and misfire in cylinder 4 & 7

i was getting an insufficient egr flow problem so i replaced egr valve, solenoid,and DPFE.....still getting the code
changed plugs, wires, MAF sensor , de carbed throttle body
fuel filter, serp belt and all fluids
and now still im getting an intermittent misfire.....and an insuffucient egr flow

and can a bad O2 sensor cause a misfire???

truck ran great for a couple days after i changed the plugs and wires then like **** again, and it runs really bad when its cold i have to warm it up for about ten minutes for it to run right

 

I'm the OP and my problem pretty much solved itself when a catalytic converter caught fire and took the rest of the truck with it.

I never did figure out what caused the problems. I had dumped hundreds into the thing and nothing ever changed for more than a few days. My insurance company gave me a lot more than I ever expected I would get and my life has since been much simpler now that the POS is gone. I'm just grateful that my kids weren't in the truck. It went up pretty quickly.

The only piece of advice I can offer is to figure it out quickly and make sure your insurance is paid up.

 

Wow, glad nobody was hurt. Sounds like your cats were clogged.