My 2005 F350 doesn't produce any boost at idle. The result is dog slow acceleration off the line until the boost hits about 5psi and then it seems to take off like a 3.5 ton rocket.

Is there any remedy to this other than brake-standing? It would seem like a few PSI would go a long way towards making this truck a lot safer crossing roadways (especially when towing a trailer).

 

On my stock truck it is maybe .5 PSI. I do notice the turbo lag, but it's not what I would call dangerous. Maybe 1/2 second and she's up to speed.

 

I've got zero at idle.

The turbo lag is something you have to get used to. Most importantly, don't push too much throttle. If you do, the PCM ignores the throttle position input, and uses its own slow-assed acceleration algorithym, to prevent smoke and excessive emissions. The trick is to give it all the throttle it can use, but no more, until the boost spins up.

The folks with manual transmissions have a steeper learning curve on that.

 

That's just the way they are, it sucks. I don't know if this is possible but if there were some way to have even 2 psi at idle I think it would make a huge difference. If I spool up only 2 or 3 pounds of boost on a brake stand, I'm obviously not gonna fly off the line but the acceleration is noticeably better.

 

Assuming your unison ring isn't stuck and no leaking CAC boots.....that's the difference between a turbocharger and a supercharger. The turbo functions off the pressure in the exhaust (almost none existent at idle) where as the supercharger is powered by a belt or gear connected to the crankshaft. Having dealt with all three options when it comes to diesels (normally aspirated, turbocharged & supercharged)...turbo is the only way to go (IMHO). Just have to deal with the minor lag from a standing start.

 

Instead of flooring it, feather it as Bill (bpounds) says above..... You'll get the hang of it soon. OR, if you are out of warranty, stick a tuner on it.... AFTER you've replaced the Torque to yield head bolts with studs.

 

Unison ring is probably fine... It develops boost pretty well once it's moving. And the boots are fine too. I had everything apart a few weeks ago and inspected it all.

My little VW Golf TDI made boost at idle. It was 1.1psi. Which was just enough. And when it wasn't there (like when the MAF went bad), you knew pretty much immediately.

I've never had the pleasure of being behind the wheel of a supercharged diesel (probably more for boats, I would assume), or an NA.

These VGTs (and VNTs) were supposed to be the panacea for turbo lag, spooling up quickly at low idle. I guess that hasn't panned out. I remember reading about a twin turbo setup using two different sized turbos to deliver power at idle and at speed. Don't recall the make or model, but something like that would seriously improve the overall ability of this truck.

After having the 7.3 for so many years, I got very used to having power when crossing the roadways near my house. That power just isn't there for the 6.0. It comes on, but not until I've creeped into the middle of the road. And then there's still 40 feet worth of truck and trailer to get across.

 

Which tuner is recommended? I'm way past warranty, and just did the head gaskets and studs and an EGR delete. So I'm ready for a little juice.

 

That's what they did on the 6.4L Powerstroke. Twin turbos, 1 large, 1 small. I guess it is better, but they still have turbo lag. Then on the 6.7 they went one better by reducing the exhaust flow path between exhaust port and turbo, by reversing the head flow and exhausting toward the center. Better still, but still has turbo lag.

 

This is why I love my manual tranny. Lol.

 

That TDI engine is a little less than a 1/3 of the engine in your truck. And I'm willing to bet a tank of fuel the turbo is equally smaller than the stock hair dryer on your PSD...not a fair comparition. Add on top of that, it's moving a car that might weight 4k pound maxed out with bodies & luggage? A F250 is designed to drag 16k-18k GCVW down the highway all day long. I used to drive a C12 powered T800, you'd think with 430 hp & 1300 Ft/Ibs of torque that monster would shot down the road with an empty trailer...it still took the turbo to spool up before you'd get power out of it...and it wasn't until you got on the "high side" of the tranny that it would really come alive. All three are turbocharged diesel with electronic ignitions. But clearly different animals when it comes to power. The car is designed to move quick, the two trucks were/are designed to move mass.If you've ever driven a 6.9 or late '80s 7.3L IDI powered truck, they were naturally aspirated. Supercharged diesels have usually been Detroit's (since they're 2-cycle, they need the forced air to feed the cylinders. And those types of engines are usually found in F650 sized trucks and up & stationary generators.Maybe I've got a wicked truck, but I can hear my stock 6.0L (well, it's got pyro, fuel & boost sensors) spools the turbo at 900-1100 rpm...and the EV2 boost gauge shows pressure (2-3 psi) right at about 1100. The VGT is better than the straight vanes on the 7.3L PSD. That's how the 6.0L makes more power and usually gets better mileage than the 7.3LI'd check the unison ring then if you saying your 7.3L had more power than a 6.0L...assuming same rear ends & stock tuning.

 

Maybe we need a bang-bang or anti-lag system on it. A little propane in the exhaust manifold maybe (since diesel fuel would probably only create a lot of soot, and I'm not sure how you'd get it there without detonating it anyway).

 

IMO, it doesn't need a thing. I've learned how to operate it.

 

A tuner will fix that for the most part. I'm using tunes from Gearhead. When I was running stock and needed to get moving, especially while towing, I would get on the accelerator a little before I needed to go. Get on the pedal just a little bit and that weight behind you will let you build some boost without moving more than a few feet. When the lane clears, smoothly accelerate as mentioned above. You will have to accelerate smoothly even with a tuner (albeit for different reasons, so as to not leave a bunch of rubber on the road), so you might as well practice now.

 

Interesting. I had a 2wd 7.3 (a 2000 F350 extended cab) before (which is why I traded it in). I would assume 3.43:1 or something close (I never checked). I'm betting the 6.0 has 3.73:1 or possibly 4.10:1 since it's 4wd and has a gooseneck hitch (which looks very factory, but may be aftermarket).

I'm pretty sure I don't see any boost anywhere near 900 or 1100 RPMs (but I'll double check). Could be an easy fix.