2000 f150 "cough"

[K_Josh87]

okay,

actually have had this issue on two 2000 f150s one with 186,000 on it, full dual exhaust, not cats blah blah blah... The other 215,000ish miles fully stock exhaust...

Both had k&n air filters that where not clean...

So, one truck is my nephews and other is a friend of mine, and both ave actually had the same things done to them to try to remedy the issue... both have had fuel filters and air filters replaced, and mass airflow sensors cleaned, and injector cleaner run through both of them.

Both claim they run better, but the trucks both ran OK when it was warm out, and now that it is cold they run rough and choke out and cough and almost die when they are cold... the colder the ambient temp the worse... Is this a possible coil/spark plug issue? What else may be the culprit, I do not think either truck at this time have CELs on, however my nephews did throw a lean and misfire code before I did the work to his... the other had no light on...

I am running on a fairly low amount of info as I do not own either truck... but I did drive the nephews truck for a couple days to see what it did... (actually he brought it to me to do breaks, and it was doing this as well, and I started into trying to remedy it as well)...

So any insight is appreciated, I may try to work on these some more, or at least gather some insight to point them in the right direction if they take it in, as the one has been to ford a couple times, and they never even bothered to check or replace the air filter.. ( thought that was kinda standard procedure for an oil change... but i guess that's why i don't pay them high prices and just do it myself)

Thank you

[leech~~]

How long ago did they put in the k&n air filters and are they in an open air box now or did they just put them inside the old closed air boxes?

[Wolffy]

Maybe check for vacuum leaks or possibly a cracked intake. Spray carb cleaner all over the intake with engine running and listen for engine fluctuations. I don't think this is the issue but it's easy to try.

I've heard that the k&n filters can be more of a problem then good. Maybe clean the MAF sensor again.

I know the newer 5.4s can run lean with a k&n and cold air intake and dual exhaust makes it worse.

[leech~~]

Maybe check for vacuum leaks or possibly a cracked intake. Spray carb cleaner all over the intake with engine running and listen for engine fluctuations. I don't think this is the issue but it's easy to try.

I've heard that the k&n filters can be more of a problem then good. Maybe clean the MAF sensor again.

I know the newer 5.4s can run lean with a k&n and cold air intake and dual exhaust makes it worse.

That's kind of where I was going with the K & N filters as well.

[jdfisherman]

Had a similar issue with my Chev - ended up being the intake manifold gasket.

[K_Josh87]

I used to own the one my nephew has, and I put the k&n in the existing box... I''m guessing around 50,000 miles.... not positive... But it think i bout the truck with about 40,000 on it...

The other one I have no idea... I know she has owned it for a few years now and it would have came with the truck... my guess this was the first time it had been looked at even...

That would seem to be an easy thing to check...

[leech~~]

Well, when it's cold like this I say when in doubt. Throw a bottle of Iso, and injector cleaner in! Seems to work just about every time!

[Jeremy airjer W]

Have the intake smoke checked for leaks when the engine is cold. Classic symptom of bad plenum gaskets.

The lean code would also support this theory.

[K_Josh87]

funny thing is my nephews truck he claims runs pretty decent in comparison now, and i did dump iso heat in that one, as well as lucas injector cleaner in it... The other one I have suggested she pick up some ISO for it and try...

is this possible EGR issue, any chance of plugs being a culprit at all? both run smooth other wise...

I just want to make sure when I check this thing out again I am checking everything that could be the issue, and try to get it running smooth for her without much hassel