02 f-250 7.3. Only mods are edge tuner, turbo back exhaust and k&n filter. Every once in a while, when the truck is cold, it has absolutely no power. There is no boost and the egt's go way up to about 900* if you let it. The transmission still shifts but the top speed is only like 30mph. Then all of the sudden it will kick in and run fine. The truck has around 180K miles with lots of towing but still runs great. Any help would be greatly appreciated. Thank you!!

 

Its called an exhaust back pressure valve (EBPV) and what you're seeing is normal. Its a butterfly valve on the outlet on the exhaust side of the turbo that closes in cold weather to put a load on the engine. It helps to warm the engine up faster. It should disengage at anything over half throttle. They have been known to stick or not want to disengage if the connection gets interrupted or you run a smokey program.

Oh, and if you decide you want to keep your engine any longer I'd suggest you lose the K&N filter. Its hands down one of the worst thing you can do for it aside from dumping a pound of sand down the intake.

 

interesting,be it a gasser, but i have 140 k miles on my 04 5.4 van,139k+ miles were with the k&n clone-s&b-i service it once a year when i do my once a year oil change with amsoil 0w20 and amsoil eao oil filter #11 -btw- i do oil analysis at this time,the silicate levels are next to nothing, so that must tell me s&b is a superior filter to the k&n?

 

Yes but a turbo charged diesel ingests more air are at any given time than a 5.4 does and rounding off the edges of the turbo vanes can be done easily with a crappy filter. I woudlnt chace an expensive diesel engine for the gains of a couple hp and FTlbs of torque with a K&N aftermarket filter.

 

gasser Super Duty = K&N good!

turbo diesel Super Duty = K&N bad!

 

i know it's apples to oranges but still its a turbo- my 89 20th anniversarry ta with 3.8 l v-6 turbo[from grand national fame] ,bought new- 182 k miles,only internal change was timing chain at 100k,have run intake on it since new with k&n,btw-not only did i buy the car new , still runs 11.0@121, and on oem garret turbo,i do let it idle after hammering on it,but no turbo timer-now this is with a turbo on a motor driven up to 6k rpms, and vanes on turbo are impeccable for the mileage,so now i guess it's a diesel thing huh?

 

No just relaying what I have heard.

 

Your right ~ it is apples and oranges. The Buick GN runs great with the K&N. I run a K&N in my '89 stang even on dry lake beds when I lived in Cali with no prob (obvioulsy needed clenaiing immediately when I got home). My quad runs a K&N (albiet with an outwearers cover)...no problem at all, actually a benefit.

I don't necessarily understand the situation with the turbo-diesel, but two friends of mine have had issues with their Ford turbo-diesels. They do however do alot of off-roading. Still shouldn't make that much of a difference. It could be a problem with the factory design or a combination of the turbo air requirement coupled with a bad design?? Don't know...anyway, Powerstroke73 knows his stuff on this issue and hopefully he can chime in with more details.

 

Bottom line you can't compare a gas turbo application on a diesel turbo, its still apples to oranges. On a gas engine you're making what 5 to 10psi unless you've got some HEAVY mods. A stock diesel sees 17psi, and when you put a chip on you can run up to 25+psi on the stock turbo. You flow WAY WAY more cu ft of air on a diesel than a gas engine which is what causes the problem. If you hold a K&N filter up to the light you'll see all kinds of little pin holes in the media. This is because they use a packed gauze media. You're better off with a paper filter or a Green filter because it uses a cloth media. Ford for awhile actually issued a bulletin to dealers to deny engine warranty claims if a K&N was found on the truck because of the number that came in under warranty for dirt ingestion.

 

Yup..Ford (and others) truck gas engines are not built to the specs used for a turbo or even a supercharged application as a production engine. They can handle them, sure with no prob, but with the lower psi as described above. The Ford turbo-diesels are built knowing that they are going to be using a turbo (or bi-turbo like the 6.4L) or such therefore they have the full cast iron motor (including the heads)...a very heavy, thick block (18 bolt main I think) that can handle the pressures of a turbo on a daily basis for many miles!! That's why they can handle a bit more psi than their lil' bro gasser motors...and can be modified to go insane with psi numbers like Powerstroke73 explained above.