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No Boost! HUH??

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Old 06-07-2012, 05:42 PM
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No Boost! HUH??

Ok, so let me long-windedly explain what's going on and what I've already determined, and maybe y'all can make some suggestions.

This is my first powerstroke. Bought it three weeks ago. (Chris and the gang were very helpful, by the way. THANKS, GUYS!!) 2001 F250 6-speed. Had a terrible miss. Turned out to be a shorted UVCH. Got that fixed. The truck gets around, but it's weak, and sounds like its detonating under load. Also smokes a little. On Chris' suggestion, I pulled both valve covers and torqued the injectors, rockers, and glow plugs. 800 miles back it got 15 quarts of Rotella 15w40, Motorcraft FL1995 oil filter, Wix fuel filter, and the left UVCH. The oil is still somewhat clear, and it has used maybe a quart in 800 miles. I've blown out the EBP sensor tube, checked the sensor for plugging (it's not pristine, but I can see all the way to the diaphragm), and I've unhooked the red line from the wastegate actuator. I pulled the turbo inlet tube and checked for free rotation, slop, and endplay. This all looked good. I started the engine and could see the c-wheel rotating at idle. (I only ran it a few seconds) I was bothered that I could NEVER hear the turbo, so today I got a tee and some 1/4" fuel hose and teed a 0-30 psi gauge into the MAP sensor hose and put the gauge on the seat and drove home. At 60 in OD I saw ~2 psi on the manifold. This tells me why the engine is weak and why it smokes a little, but now I've got a bigger mystery: If the turbo rotates freely, where's my boost?

Any thoughts?
 
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Old 06-07-2012, 06:04 PM
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4" pvc cap in the intake tube and pressure it up to about 20psi.. spray soapy water and check for leaks
 
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Old 06-07-2012, 06:17 PM
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Boost sounds about right at 60mph just driving along in my opinion. Only real way to get boost is under a load, boost is actually the pressure built up behind the intake at the compressor compresses it, when freely flowing at little or no load all air(boost) is essentially being used by the engine. Without a wicked wheel, the turbos aren't really loud.
 
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Old 06-07-2012, 07:58 PM
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2 at 60 is right i only see 18 when im pulling 10000lbs.
 
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Old 06-07-2012, 08:12 PM
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I agree that your current boost psi sounds normal. DO a search on here for boost leak detector and you can build one of those to confirm you dont have any boost leaks but its possible that what you're feeling is just the plain old 7.3 sluggishness. I had to drive without my chip for a couple weeks and it was killing me.
 
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Old 06-07-2012, 08:13 PM
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Ok, fellas, I'll buy 2psi at 60 in an empty truck. Any thoughts on why it seems to have no guts at all and why it sounds like its going to rattle the valves out of the heads when I give it anything more than light throttle? I know diesels make some noise, but this can't be normal.
 
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Old 06-07-2012, 08:35 PM
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Fuel supply issue? Can you check fuel pressure? But honestly even if the fuel pressure is good it could be a result of air in the fuel lines from a broken pickup foot, clogged in-tank filter, etc. I'd suggest doing the in-tank mods, if you plan to keep the truck.
 
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Old 06-07-2012, 08:38 PM
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Bob, can you provide some guidance for fuel pressure checks (where to attach instruments, what to look for)? Also, what are the in-tank mods?
 
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Old 06-07-2012, 08:52 PM
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Here's a link to the in-tank mods:
Welcome to guzzle's In-tank Hutch Mod Web Page

As far as the fuel pressure, the best place to put a gauge is on the fuel bowl. If you do a search on here for fuel pressure gauge, or fuel psi, you will probably find some pics.
 
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Old 06-07-2012, 09:05 PM
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x2 on hutch mod.

remember to pump out all the fuel b4 dropping the tank.

xtof
 
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Old 06-08-2012, 03:05 PM
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Thanks, fellas. I looked at the mod. seems pretty straightforward, but will have to wait til I have time to accomplish it. The fuel pressure check sounds straightforward as well. I'll post the results in a couple of days. Is it possible the "detonation" sound I keep hearing is the 'cackle' I see referred to? If so, what causes it? On the way to work this morning with the cruise set at 65, I watched the 'boost gauge' and sure enough, coming up a hill, it climbed toward 5psi. It's a good day when you learn something new!
 
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Old 06-08-2012, 06:25 PM
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Could be cackle, the problem is that the fuel rails are dead headed. It can be completely eliminated by crossing over the fuel rails, either with a regulated return or Clays convenient FRx

Riffraff Diesel: Fuel Rail Crossover™
 
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Old 06-08-2012, 07:30 PM
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I had crazy-loud noise coming out of the front of the truck when I first bought mine. My exhaust system between the block and the turbo might as well have had screen doors for all the backpressure I was building. I had leaks in both manifolds, the up pipe, and the collector - I'd be looking for soot around the pre-turbo exhaust system. My entire exhaust system is now new and I can finally hear the back over the front when the passenger window is down. I also added the Riffraff FRx to work the air bubbles out of the fuel rail. My truck doesn't freak out if I get below 1/4 tank, so maybe the hutch mod was already done - I dunno.

Everything in my signature is a link... that last one is pretty handy.
 
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