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2008 Mercury Mariner Hybrid problem

7K views 6 replies 4 participants last post by  hmmeltz 
#1 ·
Hey,

Hoping I might be able to find a bit of help here. I've got an '08 Mercury Mariner hybrid (so, basically FEH) 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.

After about 10 min. A tiny bit of assist.

After 20 minutes. Maybe 3/4ths working.

After 30 minutes. 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.
 
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#3 ·
I've used this service manager for 13 years now, and he's very professional and up front. He's called me several times and walked me through every step they've done. He called again today, actually, and discussed what the Ford technical advised them. They've gone through almost everything on the car, even checking for loose pins in every electrical connector they can reach. They've also put me up in a new Explorer as a loaner for over two months now.

The issue isn't the service guys. It's that this problem doesn't seem to make sense. It's not temperature related, like most problems when your hybrid system isn't working efficiently. And almost everything else has been ruled out. Just looking for ideas of maybe something someone else experienced and figured out...
 
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