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Discussion Starter #1
Ok I know ive been getting bad milage for a while, but wanted to check it get some good numbers. Its taken a while since I don't drive the truck alot.

Anyway I just filled up, 68 gallons 30 AUX and 38 main. Got 11 mpg driving was about half city traffic half freeway.
Just sold a trailer and deliveried it today, got 5mpg with the empty trailer, 32' enclosed GN trailer guessing 6,000 lbs. No freeway all highway, few stop and take offs went about 55mph. Road was kinda hilly.

So whats making my milage so crappy, its never been good. Best was about 16, when I had about 20,000 on the truck I have about 60,000 now. It went down once before to about 8 on the freeway once.

Truck is a 2003 7.3 4x4 supercab long bed auto 3.73s one size bigger tires, H2e turbo, DP chip, valve body.

I think thats all that would matter, I have a lot of other mods on it but none that would matter. I know the H2E gives me a ton of lag taking off.
I have stock injectors, and don't want to go bigger if my milage is already this bad.

Thanks
 

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Discussion Starter #2
OK I read my codes. Got some new ones now.
1211 this one always comes around
475 can't erase this one... pexhaust pressure control valve
231 New one...fuel pump secondary circuit low?
743 torque converter...guessing from the TC lock at too low of a speed
 

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I to, get very poor fuel mileage. I hope someone can help you/us fgure this out.
 

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idunnoyet
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Truck is a 2003 7.3 4x4 supercab long bed auto 3.73s one size bigger tires, H2e turbo, DP chip, valve body
Has your odometer been set for your tire size? Seems like a stupid question but my speedometer was a little off and it was throwing the fuelmileage way off.
 

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check the fuel pressure.

the tc error if memory serves me correctly is a t/c slipping error.
 

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First I'd have to agree with the tire size being correct. That will throw off your readings. I wouldn't think that much though. Does the truck have the same power it's always had? Have a fuel leak? Smoke excessively?
 

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I have basically the same truck and I have never seen better than 12mpg. I have 114,000 on it so it should be broke in. I pull a 12x6 enclosed trailer everyday and average abought 8mpg. I would also like to know WTF...
 

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p1211= injecthion control pressure above or below desired. probable causes= ipr valve failed/stuck ipr/shorted to ground. po475=exhaust pressure control valve malfunction. probable causes=open/grounded ckt,solenoid open/shorted,failed pcm. po231=fuel pump circuit failure. probable causes are fuse,relay,inertia switch,fuel pump,open/short circuit. po743=torque converter clutch system electrical. causes are faulty solenoid,circuit,pcm. p1211 may be from your dp chip, the pcm sees a higher operating range and sets the code. sounds like you may have a fuel pump inlet restriction, this will cause the po231. the spec is 6'' hg max. If you have a restricion its probably the screens, in the tank inside the fuel module. they are 200 micron screens.. I have removed the module and seen better mpg. :Thumbup:
 

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ok, what i cant figure out-

And i am wondering if this is related.

The truck, when it is warm, i mean not all the way to temp, coolant is warm, but not all the way (in normal) if i nail it, it's got plenty of power, throttle response is great, turbo spools awesome.

Once the truck gets hot- It has hardly any lag, but it's slower, and i have to use more pedal to do the same thing. i.e. noraml driving, i might have to go 1/3" ont he pedal to reach 1800-2000 rpm, when the truck is cold/warm. but hot i have to go 3/4" 1 1/2" or about 1/2 pedal.

warm- sitting at redlight, light turns, slam it to the floor, it goes goes goes.
Hot- same situation. it does not lag, and the turbo spools, but it seems to hesitate (not stumbling, but as if i let off the pedal just a hair) around 1800-1900, then the turbo really spools, and then it goes on up to 3k. (see video, what i am talking about is right near the end of it)
http://www.zippyvideos.com/2760740354096636/dieselvideo/

0-60 warm is 11.38~ 0-60 hot is 17.50~

And i have the poor mileage coupled. with winter fuel i might would get 250 miles per tank, now i am getting close to 300 miles per tank. I know it's better mileage, but not by much :lol:

I was planning on doing the pre-pump mod this weekend, to see if it would help with cackle

I hope you guys can help the both of us, thank you

p.s. i have NO codes
 

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crazydiesel doing the pre pump mod is great but you realy need to get rid of the fuel module in the tank. the screens in module can cause a huge restriction! the pre pump mod AND removing the tank module will help ( not cure ) your cakle. If your fuel is aeriated sucking air, it is also being returned to the tank right inside the module. making the case worse! removing the module and letting the return line dump to the bottom will help. :Thumbup: I see you have a 10k mod. where is the resistor at? temparture can change the value? what % tolorance is it. just thinking about your situation.
 

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the 10k is removed, has been for about 2 months, hehehe
 

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Just a long shot but, have you ever replaced the cmp sensor? worked on a F550 that would only run well when cold! had no codes, just lazy when warmed up. after 3 days of pulling my hair out and cheking everthing, i put a new one in and bingo :bounce: ran great. to this day i still think when the cmp sensor got warm it would send a weak or bised signal to the pcm. funny thing about that is the truck never died or set a code? :shrug:
 

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CMP? what is that?
 

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oh, CPS doh.....~....
 

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oh, CPS doh.....~....
 

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Its the camshaft position sensor or (cmp), the pcm receives engine rotational position information from the cmp sensor. the cmp is a hall-effect device. its outputs 12 voltes to the pcm whenever it detects the iron of a spoked target wheel in front of it, and it outputs 0 volts whenever it detects the space between the spokes. the target wheel spokes and spaces are each 15 crank degrees, except for narrow spoke which indicates cylinder #1 and a wide spoke which indicates cylinder #4.:Thumbup:
 

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Discussion Starter #17
I have the CPR+ fuel system from Bob, so I don't think I have any restrictions in the tank.
My odometer is pretty close, not enofe to make this big of a diffrence.
I think the TC code is because I have the manual TC lock that grounds the wire
I have the AutoEnginuity coming so next week I should have that and can check the PSI.
I also have a EBPV terminator coming and a EBPS elminator coming too.
I just went down and picked my trailer up from service in LA (over 400 miles one way) and I came over the grapevine, and was only getting 22 psi boost. I saw that one is leaking out out of it the other day.
I think that this will help once its fixed.
 

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idunnoyet
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Yeah check the boots, the one on my hot side was leaking, i fixed it today and i could tell an immediate difference, also saw a similar problem with a 3406 CAT in a Peterbilt Rig, turned out to be a boot in the Air to Air system.
 
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