Bourmanr

Hey all, new to the forum but been a ford fan for 20+ years. I have a 97 f150 with the 5.4 in it, auto trans, (not sure what trans),has a miss in it some times, sometimes it's from the get go other times it's between 40 and 50 mph, sometimes it's only when it's under load, such as going into a strong head wind, like if I'm going 60 and hit a strong wind soon it's missing and I'm down to 40 mph. When it starts to miss I let of the gas and it comes out of it and goes good for a bit. Sometimes it's good for awhile other times it misses again rite away. I've put new plugs in it along with coils and injectors. Put a new throttle position sensor in it too. New neutral safety switch but that was for other reasons. I'm at a loss with it? Is it possible the crank position sensor is bad or the DPFE sensor is bad? I'm tired of throwing parts at it....no check engine light either....is it possible the fuel pump is going on it? I don't know what to check anymore? Thanks for any and all help... Bob

white89gt

I'd get a reader that can capture live data. Watch each cylinder individually and see which one is misfiring. The threshold is pretty high before it throws a code....

Jbrew

Most likley a coil, 90% sure it is. New coils can make it worse IF you purchase knockoffs or cheap builds. There's no shortage of those on the market.

DPFE has nothing to do with the way it runs. This isn't a bad fuel pump characteristic.

MrXLT

It IS a possibility if it's the DPFE because that happened on my older Crown Vic. One of the hoses running to it busted after a trip to somewhere out of town and I had no idea what was going on. My car ran just short of limp mode on the interstate all the way home.

Maybe these trucks are THAT different but I don't see how. So, carefully inspect both of those hoses. Mine also made a loud noise like an exhaust leak, which it basically became.

Other than that, it could possibly be your MAF. Get some electronic contact cleaner spray and spray it down with that liberally and well and replace with a brand new air filter (also from experience). Make sure everything is buttoned up tight.

Other than that I think white98gt gave the best advice. Hope you find it!

Jbrew

LOL, this is absolutely incorrect. This guy is Butthurt Troll Bourmanr and will steer you wrong. No worries, his time is short. This is one of those same guy/different user name Trolls I expect. He lasted 24 posts this time.

dubbaKlutch

I know it sounds strange but did you use Motorcraft plugs? Of all the cars and trucks I have owned I have never had one as finicky about the type of plug it runs...

Bourmanr

Unfortunately no they were auto lite something special, can't remember at the moment exactly what they were....gonna have the fuel pressure tested and then vacuum test it to make sure there is no vacuum leaks next then prob put the motor craft plugs in next. It does come up with a bank 1 lean and a bank 2 lean code when I scan it but no check engine light.

Carcrazygts2

Replace the front passenger oxygen sensor. There is a a TSB about this for 97/98 trucks.

jethat

You can pull both hoses to the DPFE off and the truck will run the same. You can disconnect the DPFE entirely unpluging it and the truck will run the came it will throw a code for that but it wont change the way it runs. Like;y a coil you might have a bad one. Scanner with live data to see witch is missing would go along way to helping you figure it out..

Bourmanr

Wound up being the o2 sensor on the front passenger side, cured it 90% I'd say...gonna take the throttle body off next and clean to egr paths in that just to be sure they are clean, heard that was a major issue on these trucks as well... egr checked out good...thanks for the help...