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PSNFNG
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16 Posts
Discussion Starter #1
I have a 2004 F250 6.0. Has Mishimoto rad, 5 inch turbo-back exhaust and higher flow air intake. No EGR delete or anything else that I know of.

I suddenly lost all throttle response, but only while in gear. The accelerator pedal still works while in park and neutral, but responds much slower. After getting it fully warmed up, the throttle will work a little. I can slowly gain some speed with the accelerator floored, but it runs very rough and has barely any power.

I have recently performed a complete coolant flush, tightened the power steering gear, flushed the power steering and brakes and the truck ran fine until about a week later when the throttle issue started.

I removed the exhaust back pressure sensor and pipe and cleaned the very little carbon that was present. Removed and cleaned the MAP sensor tube and that was clean as well. I removed the EGR valve and cleaned the very small amount of carbon buildup and replaced the gasket and o-rings. The valve was a little wet, rather than dry carbon.

Here are the figures I have so far:

Ficm main power: 48.0 off---48.5 running

Ficm logic power: 11.5-12.0 off--13.5-14.0 running

Exhaust Back Pressure: 15.0 at idle, up to 40 at high rpm.

Manifold Absolute Pressure:12.6-higher with rpms

Injector Pressure Regulator Duty Cycle: 28.5-30.4

Variable Geometry Turbo Duty Cycle: 75% at idle. 0 at koeo. After EGR valve o-rings and gasket replacement---79-80%.

Injection Control Pressure Voltage: .84 at idle. 2v at 2200 rpm. After EGR valve o-rings and gasket replacement---1.09-1.29 at idle

Voltage Reference: 4.96 at idle and throttle

EGR Valve Position Desired: 9-11% at idle. 25-40% at 2500 ish rpm. After EGR valve o-rings and gasket replacement---0 at idle.

EGR Throttle Position Signal: 1-3% at idle, 20 at 2200 rpm. After EGR valve o-rings and gasket replacement---0 at idle.

Bst:.3-1.2 only 12.6 at 3500 rpms. Most when driving was 20psi

I'd rather not bring it to a dealer and just do it myself if possible. I sincerely appreciate any wisdom you could impart upon this newb.

Thank you
 

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PSNFNG
Joined
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16 Posts
Discussion Starter #6
and if you can see those engine parameters, i assume you can see your ICP value? might be good to know that psi reading while its acting up on you. as well as the IPR % value.
The IPR Duty Cycle is 28-30% and it doesn't show the ICP for an early 2004...not sure why though
 

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EA - Eggfarts Anonymous!
Joined
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18,875 Posts
oh my bad, you put ipr up there, i forgot lol
...
you might try unplugging the ICP - its under the turbo on drivers side i believe for an early 6.0 motor, i doubt that's it but couldn't hurt i suppose if you can't see it through the obd2
 

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PSNFNG
Joined
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16 Posts
Discussion Starter #8
not that it has anything to do with the throttle response issue, but when you say the valve was wet, you mean oily wet (ccv lets oil vapor back into the intake - that's normal) or gooey/water-like wet?
I believe it was coolant/water, but it was such a small amount it was hard to tell
 

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PSNFNG
Joined
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16 Posts
Discussion Starter #10
oh my bad, you put ipr up there, i forgot lol
...
you might try unplugging the ICP - its under the turbo on drivers side i believe for an early 6.0 motor, i doubt that's it but couldn't hurt i suppose if you can't see it through the obd2
I'll have to see if somewhere local has the ICP tool and check it out. It requires a socket-like tool with the side cut out, right?
 

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EA - Eggfarts Anonymous!
Joined
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18,875 Posts
that sounds just like the IPR tool if memory serves correct... but that's to physically remove the IPR. you will only want to unplug the ICP (which is very near the IPR on your truck lol)... just unplug the ICP harness & the truck will run off of stored values. all this will tell you is if the ICP is sending bad voltages to the computer
 

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EA - Eggfarts Anonymous!
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18,875 Posts
I'm really hoping that's not the case!

That wouldn't effect the throttle response like that would it?
no, i don't think it would, unless it pooped a head gasket and its over heating - but i'm sure its not because you're instrument panel would light up like the space shuttle
 

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PSNFNG
Joined
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16 Posts
Discussion Starter #15
that sounds just like the IPR tool if memory serves correct... but that's to physically remove the IPR. you will only want to unplug the ICP (which is very near the IPR on your truck lol)... just unplug the ICP harness & the truck will run off of stored values. all this will tell you is if the ICP is sending bad voltages to the computer
This will be my first order of business when I get out of work today! I'll post the results
 

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PSNFNG
Joined
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16 Posts
Discussion Starter #16
that sounds just like the IPR tool if memory serves correct... but that's to physically remove the IPR. you will only want to unplug the ICP (which is very near the IPR on your truck lol)... just unplug the ICP harness & the truck will run off of stored values. all this will tell you is if the ICP is sending bad voltages to the computer
So apparently my engine is a late model because my ICP sensors was located on the passenger side in front of the MAP sensors area. My door sticker says November 2003, but there is a sticker on the engine that says 2005.

I unplugged the ICP sensor and it idled as normal and the throttle still didn't do anything while in gear.

The ICP psi was around 900-1000 at idle.

I don't understand how the engine sounds perfect and the throttle is normal while in park, but does absolutely nothing while in gear!

Could it possibly be a neutral cutoff switch or something like that?
 

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EA - Eggfarts Anonymous!
Joined
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18,875 Posts
well that eliminates the ICP sensor. i wish i could give yo an answer on a neutral cuttoff switch, but i do not know!
i've heard about pedal assemblies going bad, look at the pedal and you'll see what i'm talking about
 

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Master BS'er
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5,931 Posts
What's the baro sensor read? If you're not up in the clouds, then Your intake is actually pulling a vacuum. You're exhaust pressure and VGT numbers are also way off. Not really sure if that's a symptom or cause yet.

We need better data on the vgt%. It should be around 85 at idle and 15 under full load. Also find the egr position and make sure that's not stuck. It should be either close to zero or close to 5 with koeo. I forget how its wired, but either zero or 5 is closed.

First thing is koeo compare the baro, exhaust pressure and manifold absolute pressure. They should all be the same. That'll eliminate a bad sensor.
 

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PSNFNG
Joined
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16 Posts
Discussion Starter #20
What are the EOT, ECT, and TFT readings when you are experiencing the problems?
The oil, coolant and trans temps are all spot on correct. The issue with the accelerator pedal not doing anything while in gear happens regardless if it's cold, warm or hot, but will VERY slowly increase RPMs while in gear after it's warmed up.
 
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