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6.0 sudden loss of throttle response in gear only. Please help!

33K views 43 replies 9 participants last post by  6ohfasho 
#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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#7 ·
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
 
#12 ·
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
 
#17 ·
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
 
#19 ·
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.
 
#21 ·
The baro sensor is reading 12.6, the exhaust back pressure is reading 12.6 and the manifold absolute pressure is 12.3...all at KOEO. I am around 4500 feet above sea level. Is that .3 difference on the MAP a bad thing?

The VGT duty cycle is about 80% at idle and 0 at KOEO. I'll check it under heavy load this afternoon and report back with numbers.

The EGR position at KOEO and at idle is 0. I just cleaned it and replaced the gasket and I-rings a couple days ago while troubleshooting. I did also cleaned the EBP sensor and tube and MAP sensor tube the same day. None of which had much build up and nothing really changed after cleaning and inspecting them all.

What else would cause the accelerator pedal to not operate while in gear? It works in park but the response is slower, but absolutely dead while in gear until fully warmed, then responds a very little..not drivable though
 
#23 ·
and you're sure that there's no gaping hole in the IC?
maybe a boot left off or blown off after the radiator work?
a split in the plastic CAC tube? or an exhaust component bust loose?

i experience a few cases where go pedal didn't work. one being egr valve stuck open, another being the collector pipe being loose from the turbo (lol accident!). just rollin some ideas
 
#25 ·
From Ford:

VGT % duty cycle

low idle 73%
high idle 43%
cruise 55%
light accel 67%
hard accel 38%
coast 57%

DieselTechRon would say that you didn't really ever want to see a stock engine all the way at 15 OR 85 (you could see 85 tuned at idle)

Almost sounds like you are in some sort of "limp mode". What are you using to read codes? It is hard to imagine that there aren't any.

What is your MAF voltage?
 
#29 ·
I'm going to check the VGT duty cycles again at different loads and idles and see how it matches up.

I'm using a Scangauge 2 and it doesn't show any codes or pending codes, nor does it show MAF voltage. I did disconnect the MAF to see if there was any difference with it off and it was the exact same

So frustrating!
 
#26 ·
Hmm, Compare the map to exhaust pressure at high load. If the exhaust is zero at key on, then add 12 to the exhaust reading when testing. They should not be that far apart. Some scanners give the absolute reading and some give the gauge reading.

When did the problem start?
 
#30 ·
I'll try that and record the results. It started about two weeks ago. About a day after tightening the power steering gear it started, Turd250 suggested checking the charged air lines to ensure I didn't knock one off or something..I hope that's the case. If it is im going to kick my own ass
 
#35 ·
As the OP of this thread was advised.

Get it checked for codes with a quality code reader.

Get a scan tool that reads engine parameters and post the critical parameters

Baro, EBP, and MAP at KOEO (key-on-engine-off).

Drive it and get it FULLY up to temperature and report oil and coolant temps.

What is the maximum boost you can get to (on a warm engine)?


What is your ICP sensor pressure and voltage at a cold idle, hot idle, and highway cruising? Same information for IPR % duty cycle.

What are your FICM numbers (MPower, LPower, VPower) when cranking and at a cold idle?

These engines are too complicated to say "one fix fits all" and WAY too complicated to give advice without engine specific data.
 
#36 ·
I will get that info hopefully this weekend.
The mechanic that did my head gaskets and studs,(who caused this problem) refuses to put more money into it. This mechanic has basically thrown everything at it.(he claims) He also had it to a Ford dealership, and they couldn't fix it...or he wasn't willing to keep paying for it.
 
#37 ·
You don't need the socket to unplug the IPR, but if you're going to remove it the special socket makes it much, much easier. They can be had from eBay for less than $10 shipped. IMO, the 12-point 3/8 in. drive is the way to go.
 
#38 ·
2004 F-350
135,000 miles
Turbo back 4 inch to duel exhaust
Blue spring upgrade
Sinister Diesel coolant filter
Motorcraft fuel and oil filters 15w40

This all started after I had the head gaskets and studs done. the truck had no power problems prior to the work being done. The turbo veins were also cleaned at the same time. What I was told by the mechanic is that when he pulled it out of the shop after doing the work the truck ran fine. The next day he went to drive it and it had no power/ throttle response when in gear. In park or neutral the engine would rev but not as it should. At this point it has had an ICP sensor, IPR valve, MAP sensor, throttle pedal assy, under hood wire harness, EGR valve, FICM, the EGR cooler was deleted but he reinstalled it thinking it might be the problem, the PCM was flashed but not replaced. There are no codes present on the PCM. It was scanned with AutoEnginuity. HPOP pressure will go above 3000 psi at WOT so the pump seems strong yet. The most boost pressure I've seen so far is only 16-17psi which definitely low at WOT but it is hard to tell if that is a symptom or a cause. When the truck is shifted into gear the engine lugs down quite a bit. It starts hard almost like there is a load on the engine, not a long crank but it rolls over hard.


KOEO:
BARO 14.14
MAP 14.24
EBP 14.4

Low idle engine cold:
ICP 969 PSI
ICP volt 1.25
IPR % 27.7
FICM Mpower 48
FICM Lpower 12.5
FICM Vpower 12
VGT % 68.5

low idle engine warm
ICP 601 psi
ICP volt .88
IPR% 19.14
engine oil temp 199
engine coolant temp 191

Cruising speed about 50mph
ICP 1286 psi
ICP volt 1.54
IPR% 32.81
VGT 62.3
 
#39 ·
Hello everybody. I’m new to the forum, I’m a mechanic and I have a 6.0 that has stumped me.
I have the exact problem as the original post. No throttle response in gear. Response in P and N but not like it should. All values and voltages are on point, no codes. I know it’s an old thread but what was your fix? The truck came in not running. New hpop ipr icp egr delete oil cooler and head studs. I did pull the cab to do the job.
 
#40 ·
welcome to the forum!
first off, the guys here are going to want to know what year 6.0 this is, early or late build. and they'll want to see the engine data while its acting up. That should get you a good start on some suggestions.
Or even better, if you started a new thread with all that info & posted the link to it back here, that would surely generate some good traffic for you & get you fixed up!
 
#43 ·
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
Did you find the issue I have same problem. Install map, Ipr, Icp, egr valve and still no acceleration in gear. Sometimes it works but most time won’t.
 
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