Hey,

Hoping I might be able to find a bit of help here. I've got an '08 Mercury Mariner hybrid (so, basically a Ford Escape Hybrid) that is not working correctly. The Ford dealership has had my car for EIGHT WEEKS now, and the technician says he has absolutely no idea what's wrong or how to fix it.

Sometimes - but not all the time - the whole hybrid system doesn't seem to work when you start driving. No assist in acceleration, no regen braking. It comes back slowly over time, though. But when it's not working, the car is dangerous to drive (no acceleration in a Houston commute means getting rear-ended).

I've read several posts here and in other forums looking for similar issues. I've seen a lot of issues with A/C and battery cooling, including things like blender motors/actuators, and freon lines. No issues with any of those, so we've ruled that out. No issue with the filter. The Ford service department has already done a lot of things like clean almost every sensor in the system, reprogram the computer, and replace the ignition cylinder lock (long shot, but didn't help). The car is still under Ford PremiumCare extended warranty, so I don't just want to give up on it, yet.

The car is throwing absolutely no codes, so the tech is assuming there's no issue with the battery or undervoltage/current.

At one point, they gave me the car back for a day, and I made some videos to characterize the problem. I've linked to them here, if it helps.

This is the car after driving for about 5 min. Couldn't take any videos right away, since I wanted to get out of the subdivision before pushing the pedal all the way down. Shows both full acceleration & hard braking. No effect on hybrid system, and the car takes forever just to accelerate even up to 20 mph.

. A tiny bit of assist.

. Maybe 3/4ths working.

. Full assist.

Any help would be appreciated. Like I said, it's been TWO MONTHS at a Ford dealership, and they still can't even tell me what's wrong with it.

 

Having the same issue on my 08 Escape Hybrid, no codes, assist works sometimes but not all the time. If I don't drive it for 3 or more days it will not start, have to use the battery jump button to get it started. Also the ambient temperature doesn't seem to matter, it's worked just fine (when the temp was in the high 90s) for about the first half of my trip then cuts out and may,,,, may start to work again before I reach my destination.

 

If the 12 Volt battery is low or discharged, this can affect the cars functionality.
Remove the 12V battery and verify it can be charged and hold a charge. Since you don't drive the car often let the battery sit ~24hrs after fully charging.
Clear the PCM of codes by jumping the battery leads, watch

You will want to clear the memory as the vehicle can 'learn' and adjust for a component that is not quite out of spec.
Clearing the memory will reset the PCM and if anything is out of spec it will most likely trip a code if there is a borderline fault.

A battery that at full charge is 12.45V or less is a dying/dead battery.
If the battery can hold a full charge 12.6V or more, then start with basics.
Clean battery terminals and verify they are clean/tight.
Verify the various grounds/cables are also clean and tight.

Videos from OP are a bit too short to show much.
0-60MPH on a flat surface will be ~ 11seconds for the 4WD Escape Hybrid.
Verify correct tire pressure, too low of pressure will cause the car to be slow.