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Engine alternating surging / power loss with sometimes high idle

Engine alternating surging / power loss with sometimes high idle

  #1  
Old 12-29-2018, 11:03 AM
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Default Engine alternating surging / power loss with sometimes high idle

Hey all, VERY long time lurker, first time poster.

I have a problem with my 09 MMH, less than 60k miles on it, just got it 6 months ago. I'll try to describe the problem as best I can but I may not have the right words as I can't find similar problems after weeks of googling... 3 problems that seem to be related...

1. Only under certain conditions, the transmission seems to "slip" at a "shift point" and the vehicle loses power. (I know this is a CVT and these are made up terms, just trying to describe). It has almost always been right about 40 mph and under a light/moderate but consistent throttle. When this is going to happen, I can feel it and feel like can cause it. But most times, this doesn't happen. Seems to happen more in cold.

2. On a morning after the car has sat (eg, for an entire day or weekend), the idle starts normal then can shoot up to 3k RPMs. This isn't right, but it isn't horrible. Mostly it seems to indicate problem #1 will occur on this outing.

3. Occasionally, on light, consistent deceleration from about 45 mph, the car will seem to jerk a bit. Almost like problem #1 in reverse. It is very dramatic when it happens. I described this once as almost a antilock brakes problem, but smaller.

My efforts to diagnose/fix have been spotty. I've found very little online that is similar, however I once found a post here that someone described a problem similar, but was told they may not be used to how a hybrid works. If I could go find that post again, I would tell them I agreed with them. I found out that Ford had extended the warranty on throttle bodies for this year, so I replaced that. However, the throttle body looked like it had already been replaced (evidenced by the manufacturing date stamp being 4/17 on that little stamp dial). So I took the unused part back.

HOWEVER when I pulled the throttle body off, I put a flashlight down into the manifold and saw brown milky liquid. Is this normal?? It had a feel of antifreeze, but smelled of gas (obviously everything in there does), and was brown. Do I have a blown gasket?

Please help me diagnose this, as it is my wife's and she is pissed! I know this isn't just a "hybrid newbie" issue, as we have driven an 08 MMH for 6 years, and I also have driven a Prius for 2. We know hybrids.

Thanks for any and all help!
 
  #2  
Old 12-29-2018, 10:11 PM
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Default Re: Engine alternating surging / power loss with sometimes high idle

1. when cold and cold outside (hybrid battery less than 50F), assist/regen can be disabled. In the case of assist, the engine revs higher for power.
2. see #1
3. EGR issue?

Brown slippery fluid is certainly a concern. Is your coolant level consistent? If you have coolant seeping into the intake, I believe it could explain all three.
 
  #3  
Old 12-29-2018, 11:09 PM
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Default Re: Engine alternating surging / power loss with sometimes high idle

Originally Posted by S Keith View Post
1. when cold and cold outside (hybrid battery less than 50F), assist/regen can be disabled. In the case of assist, the engine revs higher for power.
2. see #1
3. EGR issue?

Brown slippery fluid is certainly a concern. Is your coolant level consistent? If you have coolant seeping into the intake, I believe it could explain all three.
Thanks for replying! I don't think this is a disablement of assist/regen, as my experience with my '08 has never given me pause like this does, and I've had that in temps -10 F before... though I'm sure the '09 could be different.

The coolant level is on the bottom side of the fill level, so until now it hadn't been a concern. When I had the throttle body off the other night, the pool of liquid was deep enough to cover the head of my telescoping light, so it was significant. I soaked all that up (confident I got it all) and put another 70-80ish miles on and checked again with the throttle body removed, and some was back, though not as deep at all. Maybe 2 50 cent pieces in volume. If that is seeping in, does that indicate a head gasket? Intake gasket? Would a compression test confirm it?
 
  #4  
Old 12-30-2018, 12:20 AM
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Default Re: Engine alternating surging / power loss with sometimes high idle

Ford had a very bad run of Throttle Body issues around that time. If your Mariner does not have the "updated" Throttle Body i would swap that out. Some people unknowingly were demanding OEM with the coolant lines these are NOT the updated design and will fail quickly
It is easy to identify the original design which used a coolant line hooked directly to the throttle body itself and circulated coolant through it.
 
  #5  
Old 12-30-2018, 07:30 AM
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Default Re: Engine alternating surging / power loss with sometimes high idle

Thanks, I do have the latest throttle body as mine looks nothing like your picture, and was manufactured (FoMoCo) in 2017, so I think I'm good there!
 
  #6  
Old 12-30-2018, 08:46 AM
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Default Re: Engine alternating surging / power loss with sometimes high idle

OK.. Go ahead and Pressure test the cooling system..
 
  #7  
Old 01-17-2019, 07:39 PM
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Default Re: Engine alternating surging / power loss with sometimes high idle

So, in case anyone was interested, it took until today to get a (final?) answer. The dealership says that it is the hybrid motor, not the transmission. This seems odd to me because I can go whole days with this operating just fine... but I guess I can't complain. Because I got it only 5 months ago, the dealer I got it from (not the same one) is offering a buyback but will not replace the motor as Ford quoted $10,000 for the work, which is as much or more than the vehicle is worth. I haven't yet floated the idea of getting a used or parted hybrid motor from somewhere, but I doubt I should do that anyways.... the one thing I would like to do (as they will probably just auction this off after a buyback) is take the hybrid battery out... it has about 130,000 fewer miles than our other MMH...

Anyone ever talk a dealer into letting them do that?

Thanks for the help all!
 
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