@Zeerok: I'm glad to hear that.

I believe the factory plugs are Iridium-tipped and when they stop working, it's very unpredictable. They're great right up until the point they don't work well at all. That's why I'm replacing my factory spark plugs next month on my '10 FEH Limited even though the ICE is running perfectly.

Also: I'm not sure how long the original plug wires last, but they're certainly getting old at 12+ years, so I'm thinking of replacing them too.

At the age of these cars, you have to think of *preventive* maintenance. Make sure you've also changed the transaxle fluid. Change the air filter. Etc., etc.

 

I am having the same exact issue in my 07 FEH. Did the spark plug replacement end up fixing the issue for good?

 

The spark plug replacement definitely seems to have helped. I thought it was solved totally but then it's happened a couple more times recently since the weather has been colder. For me it only happens when it's cold (low 40s or under) and when accelerating on an uphill grade at high speed (60 MPH or above). Letting up a bit on the accelerator makes the bucking stop.

I think that the disconcerting bucking is just the way that this vehicle behaves when the engine misfires or hesitates for whatever reason. In a regular ICE car, a momentary loss of torque from the engine isn't felt very much at the wheels when the transmission is in a higher gear. But in this fancy computer-controlled hybrid transmission, the unexpected loss of torque confuses the computer and whatever it tries to do to compensate is immediately felt at the wheels. Anyway, that's my latest theory.

 

Have you tested fuel pressure? Sounds like it could be a fuel pump/fuel starvation issue as well.

 

Hi- I likewise have a 2007 Ford Escape Hybrid having the identical problems. So far it's been a nightmare to get my normal mechanic, a transmission mechanic or a dealership to tell me what it is. What did your problem turn out to be? Thanks.

 

Has anyone found a solution to this issue? I have this acceleration issue also.

I have a 2WD 2007 Ford Escape Hybrid with about 160,000 miles. (So, it's not an AWD issue.) I replaced the coils and spark plugs a few months ago with new coils and high quality iridium plugs.

Here's how I'd describe the symptoms: It usually happens within 10 minutes after starting the car, I'm going uphill at roughly 45 mph around ~3700 rpm and accelerating with medium gas pedal, often as I'm getting up to speed as I'm merging onto the freeway. The car cycles rythymically: a brief accelaration, brief deceleration, brief acceleration, brief deceleration, etc. My speed seems to stop increasing, but the speed does not decrease either. I feel concerned that I won't be able to get the car up to the flow of traffic. The needle on the Charge-Assist gauge is cycling charge-assist-charge-assist, etc, with the pulsating surging up and down. Usually I let my foot off the gas pedal and then ease it back up. I'm not sure, but I might also be able to solve the issue by depressing the gas pedal to the floor. The problem has been very intermittent, usually running fine. But this last week, it did it several times. The weather here in Southern California has been colder than normal--probably lows of 40 degrees F and highs of 60.

Even if you don't know, I'd like to know .... Should the electric assist ever be kicking in at 45 mph?

Thanks!

 

My 2007 FEH still does this in cold weather within the first 20 mins of a drive and I’ve just kind of learned to live with it. There are some suggestions above in the thread to check fuel rail pressure in Forscan, and maybe replace the fuel filter and/or pump; those would probably be my next steps if I wanted to spend more time troubleshooting it. I don’t seem to have the issue when accelerating onto the freeway for some reason, maybe because the onramps I use near home are downhill or really long; it’s more likely to happen when maintaining 50-60 MPH on an uphill grade. I just get in the right lane in those spots and it has cost me maybe one whole minute of delay total over the past year. It doesn’t seem to be getting any worse.

If you do investigate fuel line issues, let us know how it goes!

 

Thanks, zeerok!

Have you had it oscillating for a while? (I'm worried it might be getting worse. It's only happened once, but it lasted until I slowed down, followed by flooring the gas pedal. My unreliable guess is that the oscillations lasted about 4 or 5 seconds with maybe 8 or 9 cycles. Have you experienced anything like that?

WD