Hello all, I have been on the board for a few years but have'nt been signed on in some time. Anyway... I just bought a 96 F350 4x4 regular cab, powerstroke, automatic. I have wanted one of these trucks since they were new. The truck has a DP tuner installed with 6 tunes on it, It makes around 22 23 pounds of boost when ya stand on it but the turbo seems to be lazy at normal driving speeds. Could this be turbo bearings? or do I need to fix or gut the EBV out of it? Is it better to just gut it or should I keep the exhaust valve?? I have a lot of questions about this thing... I am no stranger to putting old trucks together but dont have very much history with diesels so any help would be appreciated.

John

 

Welcome back! Hope to start seeing you around a bit more frequently. The turbos on these older trucks don't spool as fast as the newer ones do b/c they have a larger exhaust housing on them. If it seems to spool too slow(WOT from a stop and it spools around 2300 RPM) look for exhaust leaks at the manifolts and the uppipes. It sounds like you have good boost numbers though so I bet it's spooling just like it's supposed to.

If you want to check the bearing you just need to pull the intake tube off the turbo and check the end play. Grab the center of the compressor wheel and move it up and down. It should have a little play in it, but not so much that it's hitting the housing. Now try moving it in and out. If it moves in and out at all, it's just about rebuild time for the turbo. This is also a good time to make sure the wheel doesn't look sandblasted, have rounded off edges or any of that stuff going on.

Oh and also you will see some oil in there, it's perfectly normal since the CCV runs in the intake and oil goes into the intake while your driving.

 

What do you mean by lazy? At normal speeds you mean like around town? just cruising at say 30 around town, you will not make much boost if any.

 

I mean under acceleration. getting up to speed at like 1/4 to 1/2 throttle. there is a big difference from when the turbo is cool to about 10 minutes into driving it. it spools right up when its cool and boosts up around 8 to 10 psi... after you have driven it for a while its like it gets tight??? you get pretty much no boost until you stand on it then it spools right up. I dont know??

 

It could be the extra timing you have at lower temps getting boost up quicker, but really there shouldn't be much if any difference in spool time between cold and hot engine temps. so how much boost do you get at 1/2 throttle when it is at full operating temp?

 

Well,... I was checking it out last night and I found that the air cleaner was pretty much plugged. so I replaced it and that helped quite a bit. However it still has a flat spot around 1/4 to 1/2 throttle. half throttle I get around 5 to 7 pounds of boost, that is where it starts to come out of the flat spot. also all warmed up with the tuner on 4 or 5 it falls on its face and acts lean when u stand on it, but when you back the throttle off to about 1/2 it pulls really hard right up?? Im starting to think fuel delivery??? not enough fuel would make the turbo not spool in spots wouldnt it?? anyway I love this truck even with small issues... I understand the following that the powerstroke has now...

 

Have you changed the fuel filter, cleaned the screen in the bowl, and checked fuel pressure?

 

Thats kind of where im at with it. after work I am going to pick up a new filter and do that. I need to find some ford shop manuals for this thing I will check the evilbay anyway... How would one go about checking/adjusting fuel pressure

 

There is a schrader valve on the right side of the fuel filter housing just use a tire pressure guage should be around 50-60 at idle. As for the ebpv just unplug it and you will have less problems with it. Gut it if you want

 

The falling on it's face thing is probably running out of high pressure oil. With stock HPOPs and tuning the HPOP can have a hard time keeping up with demand. If it can't keep up and ICP drops down, the truck falls on it's face and EGTs will start getting hotter than normal.

You need to check it, but that would explain why it falls when you floor it then runs better when you pull back to 1/2 throttle. Asking for less HPO, now the HPOP can keep up with demand and it runs better as a result.

 

I was starting to think fuel... I picked up a new fuel filter last night and figured today after work I am going to tear it down a little clean it up maybe pull the FPR apart and clean then put it together and see what happens. I was looking at the HPOPs at different sites and thinking about it, but my question is my truck has 200,000 miles on it. the oil is clean and stays clean throughout its life cycle, you can still read the dipstick through it before u change it. so I believe it has been cared for. but should I think about a freshening up before I worry about throwing fuel at it??

Thanks for the help Gents.

John

 

Do you mean freshen the motor before you put bigger injectors in? If that's what you mean, don't worry about the motor. 200k, its just broke in

 

Yea I was asking about freshening the motor.. Im glad to hear thats not an issue yet.
Yesterday I cleaned up the fuel bowl, FPR, and replaced the fuel filter. after that I am seing about 62 pounds on a tire gauge. I also disconnected the wire off the exhaust valve. It made a huge difference... I think she'll tug a house down now. I think my next project is going to be gutting the exhaust valve.. any pros and cons to this?? any advice??

Thanks

 

I see no cons to gutting it. I live where it's good and cold and don't miss it. I do have high idle on my chip though, that is nice on warmup. You got high idle on your DP?

 

Yep... it has the high idle on #2 I love that feature so far. its nice in the morning. I remember reading about someone who was boring and smoothing out the housing after they gut it. has anyone done this? anyone got a diameter to bore it to? I figure I will take it to work and bore it while its off maybe smooth it up with a die grinder and flap wheel??