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Clayton
Clayton, Mechanic
Category: Heavy Equipment
Satisfied Customers: 754
Experience:  5+ Years at Freightliner, Detroit & MBE Certified, ATD, and Electrical
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I have a 2002 freightliner with the detroit engine and when

Resolved Question:

I have a 2002 freightliner with the detroit engine and when you shift into high range it looses power like the computer is downing the engine. with out a load it runs fine but every once in a while it will but being loaded is when it dose it the most. we swamped out computer, oil presser sencer, new air filter, and fuel pump. and thoughts? vin 1Fujbbcg72lj54802 engine#06R0673056
Submitted: 3 years ago.
Category: Heavy Equipment
Expert:  Clayton replied 3 years ago.

Clayton :

Hi, Welcome to Just Answer, I am Clayton. I can help you with this.

Customer :

Hi

Clayton :

Hey

Clayton :

How are you

Customer :

good just trying to figure out this truck

Clayton :

Alright,lets see what we can do

Customer :

ok

Clayton :

I know you changed the fuel pump, have you acually checked the fuel pressure?

Clayton :

actually

Customer :

no

Customer :

but would it be different un loaded vers being loaded

Clayton :

You said without a load it runs fine, with a loaded is when it does it the most, when the truck is loaded, it demands more fuel

Customer :

well we changed the fuel pump and computer

Clayton :

You could have plugged fuel filters causing a restriction, pressure relief valve sticking open

Clayton :

I am not saying this is your problem, this is something to check when you have low power

Customer :

well it is like the computer shuts it down and picks it back up again

Clayton :

If the filter is restricted, then it does not matter if the fuel pump is new, it cant push fuel through a restricted fuel filter, if the relief valve is partially sticking open, then this will lower fuel pressure.

Clayton :

Alright, is your CEL coming on?

Customer :

but it is only in high rage low range is fine

Clayton :

when the truck is in high range, that puts more load on the engine, and the fuel demand is higher.

Customer :

no no lights comming on

Clayton :

are you getting any smoke out of the exhaust?

Customer :

no

Clayton :

I seriously would put a fuel pressure guage on it while you are driving it and watch the fuel pressure. I have seen the suction line from the tank to the fuel pump collapse and cause a similar problem.

Customer :

well we stuck a hose in the tank and bypassed the suction line it did the same thing

Clayton :

Ok, good, but we still need to know what the fuel pressure is.

Clayton :

The pressure relief valve can cause low fuel pressure. And or course fuel filters, I would also check your turbo charger

Customer :

okay

Customer :

it will take me a while to do it

Clayton :

That is fine, this question will stay open while you check stuff, and if you need to come back and ask more questions, you can at your leisure

Customer :

okay

Clayton :

Use a 0-100 pressure guage , and plumb it on the fuel temp sensor on the fuel pump

Clayton :

you will have to remove the fuel temp sensor

Clayton :

Check that out, and get back with me.

Customer :

ok

Customer :

we bypassed the filter and suction tube and put a pressure guage and at idel is 20 and at really high rev it went to 80 no fluc as long as we held the rev

Clayton :

have you tried to drive it with the guage on it?>

Customer :

?no got to get a longer hose for guage

Clayton :

let me check the specs on the fuel pressure, There is a mid year change where they changed the fuel pump, nd the engines required great pressures, I think those specs are good

Customer :

ok

Customer :

we are looking for a longer hose for the guage so we can drive it

Clayton :

looks like that is enough fuel pressure, It is suppose to be 75, but that is close enough

Clayton :

I would still drive it to make sure it does not drop under a load

Clayton :

be right back

Customer :

yep i got you

Clayton :

I am back

Clayton :

If all of this is good, then check the turbo, check the wheel play, up and down, then in and out, look for oil residue, and bent or damaged fins on both the exhaust and the intake side.

Clayton :

Let me know what you find, I am giong to step out. Just reply back

Customer :

when it doged out the pressure went from 79 to 74 so i think we have good pressure. could a sencer cause it to dog out?

Customer :

the rpms droped too

Clayton :

Ya, 74 is not to much of a drop.

Clayton :

You said you replaced the wastegate sensor?

Customer :

yep

Clayton :

I have never heard of a wastegate sensor, we might be calling it two different things. where is located so I can get on the same page

Customer :

it is the turbo sensor we replaced

Clayton :

ohh, on the intake manifold?

Customer :

yep

Clayton :

There are about two other things tha can cause low power. Check the turbo, and exhaust leaks before the turbo. When is the last time you had the overhead ran?

Customer :

turbo is putting out good air pressure and i think the computer is derating

Customer :

milage is 666 thousand

Clayton :

computer could be derating. This is non-EGR?

Customer :

yes

Customer :

we switched the computers twice

Clayton :

as soon as you swapped computers, did it run fine, then start to derate?

Customer :

no right away

Clayton :

does the fan stay on all the time?

Customer :

no

Clayton :

I do not think the computer is derating. But cannot be forsure without hookiing it up and seeing if t here are derating faults

Clayton :

does the check engine light work? maybe there are some historic codes that can give us some clues

Customer :

check engine light does work but does not come on

Clayton :

have you tried to flash out the historic codes?

Customer :

the only code that comes up is a low voltage but we have had to jump start the truck

Customer :

not yet

Clayton :

have you checked system voltage?

Customer :

yes

Customer :

14.8 volts

Clayton :

thats plenty

Clayton :

is this at the batteries or the alternator?

Customer :

batteries

Clayton :

all 4 batteries?.

Customer :

what about the ecm fuse

Clayton :

if the ECM fuse is blown, it would not run

Customer :

okay

Customer :

yes

Clayton :

I am wondering if you have a voltage drop in the wiring to the ECM. What does the dash read in voltage?

Customer :

i'll go look

Customer :

rough 14.5 volts

Clayton :

ok

Clayton :

was in work performed before this happened?

Clayton :

was any work I mean

Customer :

no just checked cables to batteries

Customer :

no

Clayton :

nothing done with the top-end?

Customer :

no we haven't this has always been one of our best running trucks

Clayton :

hang on a min, brb again

Customer :

ok

Clayton :

I found something on the DDEC 5 engines, your fuel pressure is way to high, I am trying to find it on the DDEC 3/4 engines, and high fuel pressure can cause low power

Customer :

this is a ddec 4 engine we tryed a ddeck 3 engine computer and oil pressure was way high

Customer :

sorry that was a ddec 5 computer that sent it high not the ddec 3

Clayton :

how did you manage to hook up a ddec 5 computer to a ddec3/4?

Customer :

it was a egr ddec 4 computer not a five

Clayton :

ok. your fuel pressure should be 84 psi at idle, and rated

Clayton :

i am sorry, at 1800, or 2100

Clayton :

I read that wrong

Clayton :

10 psi drop I don't think would cause your problem, maybe a fuel filter change might get you somewhere

Customer :

we were at 79/80 psi

Customer :

well we changed it and now we pypassed the filter

Customer :

bypassed

Clayton :

ok.. I dont think the ECM is derating you

Clayton :

It has to be mechanical

Clayton :

have you checked the charge air cooler, or any air system leaks?

Customer :

yes

Clayton :

turbo air system

Customer :

yes

Clayton :

and you physically inspected the turbo

Clayton :

make sure the waste gate is not sticking open, or stuck open

Customer :

yep turbo is good and waste gate is working

Clayton :

I have told you to check everything that could possibly be checked, and you have. Your truck has 666,000 miles on it, it is way over due for an overhead adjustment

Clayton :

I would adjust the overhead and see if that brings your power up

Customer :

im going to go check the waste gate again

Clayton :

ok..

Customer :

how much air pressure does it take to hold or close the waste gate

Clayton :

Pressure opens the wastegate, probably 25-30

Customer :

unless something is wrong with the waste gate it is operating with a air compresser hose blown into the waste gate

Clayton :

how much pressure are you putting to it, your air compressor could be 60+ lbs

Customer :

but if it isn't opening it should be blowing black smoke or blue smoke right?

Clayton :

if it is opening to soon, it will not make enough boost, and the manifold sensor won't see the boost, so might not enrich the fuel.

Clayton :










Garrett®?



14.0L?



550–575 Hp?



210.29-217.19 kPa (30.5–31.5 psi)?



1.016 mm (0.040 in.)?


Clayton :

Yours is a 14.0l, or 12.7?

Customer :

12.7

Customer :

i think

Clayton :

it is the same regardless, when you apply 30.5 to the wastegate, it should move .040 of an inch

Clayton :

30.5 psi

Clayton :

thats if its a garret turbo, if it is a borg warner turbo. Here are the specs on it

Clayton :










BorgWagner Turbo Systems®?



12.7?



330–430 Hp?



234.22-234.63 kPa (33.97–34.03 psi)?



1.45-2.26 mm (0.057–0.089 in.)?


Clayton :

We have a digital presure guage and regulator just for this reason

Clayton :

You might try wiring the wastegate shut and see what happens, it will build power,until you build to much then it will derate you

Clayton :

Do that at your discretion

Customer :

ok

Clayton :

but it would still should derate you for the moment

Clayton :

If you do this, it could overspin your turbo. I would not advise it

Customer :

we are going to try wiring it open and see what happens

Clayton :

if you wire it open, it will do the opposite

Clayton :

you wil lose power

Clayton :

the wastegate is designed to prevent the turbo from overboosting

Customer :

oh

Clayton :

if the waste gate opens, the exhaust will bypass the turbine wheel and exit the exhaust and not spool the turbo as fast

Clayton :

its a safety feature for the engine and the turbo basically. If it comes open to early, it might be the problem. The springs do get weak in the actuators

Customer :

well it only de rates for a moment and picks back up and does it again

Clayton :

after you wired the waste gate shut

Clayton :

?

Customer :

no its been doing it all a long

Clayton :

make sure the fins of the turbo are not hiting the side of the cold side..

Customer :

ok

Clayton :

check movement up and down as well

Clayton :

on the shaft

Customer :

we wired the waste gate open and other than a little lack of power the truck ran good it did not derate us at all it ran 75mph at 1700 rpms before we we could not get it past 1600 rpms at 55 mph. turbo pressure before it derated us at 25 psi and after wiring waste gate open turbo pressure was at 17 psi does all this sound correct?

Clayton :

It is very possible the wastegate spring is weak, or the wastegate is not adjusted correctly. Sounds like you might have fixed the problem.

Clayton :

I would like to know if you are getting derated, the only way to tell is have somebody hook up to it and look at torque percentages. If it is derated, it will tell you

Clayton :

Are you still with us?

Customer :

we put another waste gate controler on it and we are back to square one

Clayton :

you put another wastegate on it?

Customer :

the round thing with the arm on it that has a hose going to it to open the waste gate

Clayton :

yes

Customer :

would it hurt to run with the waste gate open

Customer :

yes

Customer :

we did

Clayton :

closed you mean?

Customer :

if we wire it open

Customer :

because when we did the truck would run fine

Clayton :

if you wired it OPEN, then it would have a hard time building boost, which would cut your power

Customer :

but with the waste gate closed it would only go 50 55 mph at 1500 rpms

Customer :

with waste gate open we could run 75mph at 1700 rpms

Clayton :

so when wired it open, you were able to get 25 psi?

Customer :

That was before we wired it open that is when the truck started to mess up. after wiring it open we were at 18 psi truck ran good

Clayton :

I wonder if the boost sensor is making the ECM think it is making more boost than it actually is

Customer :

That is what we are think too

Customer :

we took one off our junk trucks and it does the same thing

Clayton :

The wastegate is held CLOSED by an internal spring, should OPEN at around 30-35 psi

Customer :

yea the truck messes up befor the waste gate can open

Clayton :

Depends on the turbocharger...do you know what kind of turbo you have

Clayton :

you can see boost pressure?

Customer :

we hooked a guage to the manifold and drove it

Clayton :

ok

Customer :

psi guage

Customer :

he's going to see what kind of charger it is

Clayton :

I am scratching my head, I gave you all the possibilities

Customer :

can you tell by the vin number

Clayton :

ya..if it has not been changed

Clayton :

let me go looko

Customer :

we haven't changed it

Clayton :

I am having difficulty with the website. You can look on the turbo, it will say Garret, if its a Garrett, it will have a tag with Borg Warner on it

Customer :

it has a detroit symbol on the turbo

Clayton :

They both will...

Clayton :

does it say garrett on the cold side(intake side)

Clayton :

I am all out of ideas. Do you want another expert to help you out?

Customer :

Gattett

Clayton :

ok

Clayton :

The garret should open around 30-31 psi, and move .040 of an inch at this pressure

Clayton :

Does the waste gate have two nipples on it?

Customer :

no just one

Clayton :

ok

Clayton :

if it is not building enough boost to open the wastegate at 31 psi, then it could be derating. It takes combustion to make boost

Customer :

well Clayton Thank you for all your help in Pointing us in the right direction. we figured we just wire it open so the truck can run.

Clayton, Mechanic
Category: Heavy Equipment
Satisfied Customers: 754
Experience: 5+ Years at Freightliner, Detroit & MBE Certified, ATD, and Electrical
Clayton and 3 other Heavy Equipment Specialists are ready to help you

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Clayton
Clayton
Technician
754 Satisfied Customers
5+ Years at Freightliner, Detroit & MBE Certified, ATD, and Electrical