Sometimes Lazy, Sometimes Strong..

[Scott E]

08 4.0 126k

Hi folks... another weird anomaly... I’ve had our truck now for right at a year and we have replaced the xfer case ... front pinion bearings 2x... and still working through that problem as with all that work we have not solved the vibration/sound issue..

Well onto the new topic I’d like to share with y’all... The truck has been maintained very well and by the ‘ford’ dealership it was bought from and since we have had it i’ve noticed that there are times when pulling up through the power band.. not towing but excelerating... there is sometimes a ‘flat’ spot where the engine is running fine.. no misses or stumbles.. but ‘not’ pulling as it should... and there are times where the truck pulls very nicely all the way up through it’s power curve... we have changed the fuel filter and checked the pump... no noted flow loss....

Question is... why the intermittent power loss?

Thanks Much
Scott

 

[BenSantos]

This is tough since there are so many things that could cause this problem, and without a code to tell you where to start looking, you don't want to be chasing your tail or just throwing money at the truck.

I'm assuming that there is no engine light on, correct?

Does this happen on a regular basis?

My initial thought is that you have two options:

1. In many cases, the engine computer needs to see a 'fault' several times before it logs a code. So, you could keep driving for a few more days, see if it logs a code, and then proceed from there. Sometimes, if you have a code reader, you can also see 'pending' codes. This is when the computer has seen a fault but is waiting to see it again before it logs a real code. Or...

2. If you have access to a scanner or know someone who does, you can record the engine data while you're on a test drive and compare signal values to Ford specs when you are experiencing the loss of power.

Loss of power certainly could be a fuel delivery issue and it is not an uncommon problem. Your explorer has a fuel rail pressure sensor and a pump that is internally regulated. An issue with either of those parts could cause a loss of power and acceleration. Have you noticed a hard starting issue or any other symptoms that might point to a fuel problem?

Just my 2 cents.

 

[Scott E]

Yes... no codes thrown that i can tell... and this has been an ongoing problem since we bought her.. now a year... i’m not sure what scanner i could own... and not really sure what values i could watch... but i sure would love to solve the issue... it is really nice and peppy when working correctly...

No hard starting and or idle issues... very smooth and quiet engine...

Thanks Much
Scott

 

[Gorb]

It's all about controlling the throttle and how fast you're going when you put the gas to it.

You'll never get full power by just slamming the pedal to the floor. You almost have to give it a 2 second burst at 1/2 to 3/4 throttle then let off a little and you'll feel the pedal stiffen a bit and then you get the pull you're talking about. Just play around with it you'll figure it out

 

[Scott E]

it’s never been about a ‘WOT’ test.... this is a ‘normal’ approach to a hill or a safe passing of another vehicle.. and it is unpredictable .. in that if you are in a bit of a load already... a continued increase in throttle position yields little to no extra response as it should...

Thanks for your input..

Scott

 

[CharlieK9]

This is tough since there are so many things that could cause this problem, and without a code to tell you where to start looking, you don't want to be chasing your tail or just throwing money at the truck.

I'm assuming that there is no engine light on, correct?

Does this happen on a regular basis?

My initial thought is that you have two options:

1. In many cases, the engine computer needs to see a 'fault' several times before it logs a code. So, you could keep driving for a few more days, see if it logs a code, and then proceed from there. Sometimes, if you have a code reader, you can also see 'pending' codes. This is when the computer has seen a fault but is waiting to see it again before it logs a real code. Or...

2. If you have access to a scanner or know someone who does, you can record the engine data while you're on a test drive and compare signal values to Ford specs when you are experiencing the loss of power.

Loss of power certainly could be a fuel delivery issue and it is not an uncommon problem. Your explorer has a fuel rail pressure sensor and a pump that is internally regulated. An issue with either of those parts could cause a loss of power and acceleration. Have you noticed a hard starting issue or any other symptoms that might point to a fuel problem?

Just my 2 cents.

I agree, even a cheap scanner can show mass airflow, absolute throttle position, timing advance and others. The computer measures the airflow which is determined by the throttle body plate. Then meters out fuel to match the air flow at a specific ratio. I think you can see the pedal position also.

 

[D Hook]

What kind of fuel are you using? Any ethanol?

 

[Scott E]

Just amount government allows Maine... so fuel management ‘oem’ should be able to compensate fine...

Scott