'00, 7.3 PSD, F250 4X4, Auto Trans, 275k miles, stock tires.

Background: two injector changes; one at 180k, one at 225k. Big Wix air filter, Back pressure tube clean, Rotella Synthetic Oil, AIH Removed, unable to locate any boost leaks, no exhaust manifold leaks, ScanGauge II installed, stock exhaust with a Magnaflow Diesel muffler, no play in turbo. Engine starts easily (warm or cold weather) and runs great.

However, fuel mileage is horrible, in my opinion. Empty: Hwy; 12-17 (ya never know what it's going to be) usually runs around 13.0-14.2, City 11-13. Although, last year on a 440 mile trip, got 19.2 mpg hwy, returned to same fuel pump, filled up and went on a 180 mile hwy trip and got 14.2 mpg. I can expect 12-13 hwy pulling a bass boat.

Hooked a fuel pressure gauge up to it and checked pressure... Idle and no load rpm pressure was in spec., didn't have enough hose to run in cab and go for a drive. I don't jack rabbit start or drive it hard. On hwy, I try to keep the RPM below 2000 (70mph)

Here's some scan gauge readings, speed controlled by cruise control: 75* air temp, 55mph: level ground, ICP 761-825 #'s, Boost 1.5 #'s.. Slight-Mod hwy uphill grade (don't have %) same air temp and speed. ICP 853-923 #'s, Boost 2.3... Slight down-hill- ICP 738-770 #'s, Boost 1.3...

I also noticed the coolant temp is running about 153-160 on a 40-50* day. The engine oil runs about 15-20* hotter than the coolant temp (all thru Scangauge II) Do I need to change the thermostat since it's running so cool?

I need your best advice on this.. I'm game for any and all suggestions. Fuel being the price it is, and no relief in sight, I need to maximize my fuel economy.

Thanks

 

Your mileage doesnt sound bad to me.... I think some of the problem might be the change to winter blend fuels this time of year.
Have you checked your EBP tube and sensor to make sure they are clean and clear, this can affect mpg.

 

You may have put bad fuel in when you filled up before the 180 mile trip. Have you checked the fuel filter to see if its clogged. Which CPS are your using? Have you done an injector buzz test?

 

Your boost reading is low. You should get about 4 PSI at 60-65 MPH on the flat with no wind. 70-75 can yield 5 PSI under the same conditions.

When you looked for boost leaks, what method did you use? I had a small leak on my passenger plenum and I could see my boost drift up and down with no change to anything else. Chris had a leak in his compressor seal. I've seen bad MAP and EBP sensors give erronious readings and power/MPG loss could be coupled with either.

When you refer to your MPG, are you talking overhead or hand-calculated? I can get about 19.5 MPG on long hauls with no stops, but I don't dip below 16 MPG when empty - unless I'm driving in some nasty weather or road conditions (hand calculated).

 

John2001--EBP Tube and Sensor are clean... It's getting roughly the same mileage summer or winter blend..

DP-TUNER-- Buzz test next on list (don't have a laptop to conduct test), Fuel Filter changed after that trip (only have 8k on fuel filter), The CPS went down a couple years ago and had to change it (i believe gray was the only one avail). Then I went to FORD for a recall on the CPS and Cruise control- I believe they installed the Gray CPS.


Tugly-- MPG is hand calculated. Don't remember the name of the procedure, but I used a piece of PVC pipe with an endcap and a schrader valve affixed to it then hooked an air hose to it, then sprayed everything down with soapy water. If you have another suggestion, I'm all ears.

 

That's the one... I had to cover the basics. Many have looked for leaks, but didn't check all around the plenums (I only caught mine by accident). Chris ended up swapping out his turbo with a used one to get his boost back to normal.

The last link in my signature might yield some ideas not tried yet. One mentioned in there is making sure the MAP, BARO, and EBP sensors all match with the engine off. If the MAP is off from the BARO, your boost reading will lie to you.

 

On a side note, I've been all over the engine with a flashlight and mirror looking for exhaust leaks. (in anticipation of weak boost), none found. Going down to do a pos. pressure air test on boots, spider, etc, just to be sure....

 

Ok, 2 hrs later and some new findings.... Did the air pressure test on the Turbo Boost system, no leaks found... Turbo compressor wheel has play in it, can wiggle it up and down and side to side with a pair of pliers, no play in it when pushing in or pulling out.

So, what do I need to rebuild the turbo and reinstall it? Where can I buy it (that's not going to cost me my right arm)? Approx price? and, will this problem cause low boost?

Did some of the tests In Tugly's post via use of Scangauge II.. Here's the results: EBP 14.2 KOEO, EBP-idle 14.6-14.9, ICP-idle 470-503 (constant changing), IPR-idle 11...

I ran the engine at WOT for about 20 seconds (sure my neighbors would be complaining if I let it scream at WOT for 2 min), the following are the numbers: EBP-38, ICP 1460-1665, IPR 20-26...... any thoughts???

 

Did you get the KOEO for MAP and BARO to compare withe the EBP?

For those unfamiliar, this is a reference absolute pressure reading for the atmosphere. The KOEO EBP is saying the air pressure is 14.2 PSI, which works out to about 1000 feet above sea level. If all the sensors agree here, then it's usually an indication that the sensors are working correctly. The BARO (if equipped) always reads atmospheric pressure (altitude) and is a baseline for comparing with the sensor reading. If SNIPER168308's sensors are not working properly, the fueling would be unpredictable and the MAP sensor may give the false impression of a lack of boost.

I bought a used truck and the MAP reading was wonky, and I didn't know it until I looked at it. It turns out the PO installed a mod on the MAP signal and the mod failed, robbing me of power.

 

Here is a link for turbo rebuild for 7.3, it is for a van, but as stated at the top of the page very little difference, Guzzle sells the rebuild kit, iirc.
Welcome to BDrummonds Van Turbo Rebuild Web Page
Phil

 

Tugly,

I'm not sure how to get the Scangauge II to give me Baro or MAP readings.. is this something I will need a laptop to do?

 

wild-goose chase (plural wild-goose chases) (idiomatic)

1. (figuratively) A futile search, a fruitless errand; a useless and often lengthy pursuit. <dl><dd>I went on a wild-goose chase all over the town looking for that adapter until I discovered they no longer make them.</dd></dl>
2. A task whose execution is inordinately complex relative to the value of the outcome. <dl><dd>Diagnosing this software application's problems is a wild-goose chase because it is built in an environment that has poor debugging tools.</dd></dl>

 

You know, even though Cody is a young buck, I think he could well be on his way to replacing Gene with his posts.

In short, he's saying, don't waste your time with a scanner looking for your problem. The truck doesn't have enough sensor readings to tell you what you need to know.

Now for a question from me. Two injector changes? I assume you mean you have replaced two different injectors at separate times? Why did you replace them, and how did you determine they needed to be replaced, and what did you replace them with?

Also, are you filling up to the exact same "full" point each time you calculate your mileage?

 

You dont need to rebuild the turbo!! up and down/ side to side is fine as long as the wheel is not hitting the housing. If you have in and out play (which you said you dont) then you need to rebuild. Dont use a pair of pliers either next time just use your fingers, you dont want to take a chance in hurting something that isnt hurt anyways....... Keep the $100..... or mail it to me

 

Young buck? Me? I wish. I'm a half-decade from the big 4-oh!

You read my mind though, Chris!!!