Hi everyone. I’m at a standstill and very frustrated. I have a situation that’s been happening for about a year now. My Expedition often tends to have a feeling of loss of power at highway speeds. When pressing the gas- it often will slightly drop rpm and the engine hesitates.

It’s NEVER caused a check engine and I’ve replaced common parts: (Spark plugs/coils, cleaned throttle body/MAF, changed the Cats, new fuel filter). I had a rebuilt transmission because it went out on me 6 months ago- I was excited to think that this was the issue but sadly it wasn’t. It still does the same thing. I’ve taken it to 4 mechanics and they all look at me like I’m crazy and say “it runs perfectly fine”.

It’s one of those things where only I know that somethings wrong because I know exactly how my SUV is supposed to feel and something is off. They also tend to punch the gas when test driving which causes them to never experience what I’m talking about because “punching the gas” is the only way that I get it back up to power. You can only notice this issue when driving normally. Any idea where to start/have you had the same problem? I’m tired of throwing money at this issue. I can troubleshoot because no codes are stored for this issue. P.S I’ve also reset the ECU/drain the capacitors many times with no luck :/

 

Maybe we can offer some help, maybe not, what a way to start.


What if you told us for example at what speed does this take place, only on acceleration, approaching a hill, engine hot /cold. Any information you can offer, no matter how unimportant you might think it is could help shed some light on what might be happening OR, not happening.
We attempt to look for anything unusual that might seem unimportant and need to check how this can affect performance.
Can you do this?
Do you know if any shop pulled up your vehicle's data stream info ? Things like MAF reading, fuel pressure, fuel trims. At this time we don't know if it is fuel or ign related. Hopefully info you might provide will allow us to look deeper into the problem.

 

Hi, thank you for your response. Any help is appreciated. As far as specifics:

This problem only seems to happen at about 30mph+ (more noticeable on the hwy at 55mph*). The grade of the road doesn’t seem to matter. If anything- going up a hill; the truck performs better because of the amount of gas I’m applying. The more gas I apply- the less problematic it is. When the problem happens (engine hesitation/rpm drops a few hundred), I have to punch the gas to get it up to par then it goes back to normal only to do it again a few moments later. Basically- I can’t drive normal with a light foot. I have to always press the gas hard. Not necessarily floor it but rather drive aggressive on the highway. My total driving range is supposed to be about 300miles between city/highway but I only get about 210 on a full tank, so my mpg sucks. The problem is almost non existent local driving.

I do remember finally getting a bad o2 sensor a month or 2 ago but it went away on its own and never came back. It idles perfectly fine at about +/- 650rpm

I have noticed that this problem is reduced on cold days. I have a Bluetooth obd2 scanner which can pull up virtually any info on my SUV (air, fuel trims, percentages, emissions, and so on) but I’m not really sure what I’m looking at or “how to read” the info. All I know is that no check light is present on the dash or in the stored memory.

 

Can you post the data stream info, thank you.

 

Hi,

Attached are a few screen shots I took of my last drive cycle. I can only view 2 functions at a time so I tried to group systems that functioned together as closely as possible. The only thing that really caught my attention was the Fuel Pressure kPA and the MAF g/sec. They seem very sporadic. However, I’m not sure exactly how to read these charts or at what intervals it’s measuring. Hope this might help..