strange revving with my hybrid while coasting

[maroonhoo]

Hi guys,

 

I'm turning to the experts -- you guys -- since my question has managed to stump two Ford service departments.

 

I bought my car in March, and since then, I have twice experienced a strange revving-like noise coming from the front end of the car while coasting. The revving is a constant, deep moaning noise, like a sport's car's engine when it's revved, only the revving is constant and doesn't stop until I start accelerating again. When I coast, the noise comes back and doesn't stop for tens of miles. Both times it has happened since I bought the car, the noise was loudest and most noticeable while coasting without my foot on the gas or brake. When I accelerate, the noise is more subtle, but still constant.

 

Is this normal? Does any of this have to do with the battery? The battery was at the mid-point this last time I heard the revving noise. I've already put 6500 miles on the car, and like I said, this is only the second time I've had the problem. It has happened at highway speeds (65+ mph) and lower speeds (~45 mph).

 

Does your hybrid do this?

[lolder]

No.

[Buster1]

Sorry man. Not normal.

[maroonhoo]

No.

 

Ok, anyone experienced with cars want to take a stab at what the problem might be? The noise is really loud, but because I can't reproduce the problem on demand, Ford hasn't been able to hear it. What types of problems might make a car do that?

[maroonhoo]

Sorry man. Not normal.

 

I suppose I am in for another unproductive trip to Ford... They don't know what the problem is either. :(

 

Thanks, guys.

 

If anyone else has had this problem, please let me know if you found a solution. If Ford finally gets it together and diagnoses the problem, I'll post the solution here.

[DaveM]

Change the display so it shows your RPM's and see if it is the engine doing it. Also check to see if the elec. motor is going up in power. If neither one seems to be the culprut, then I bet it may be your electric fan making all that noise. You have let off the gas which for the most part cuts either all or most of the power depending on if you are above or below 47mph and with all that quiet you can now hear your fan kicking in. On my motorhome when I let off the gas at certain temps and speeds the electric fans come on and it sounds like 3 more engines starting up and running at full power.

[oldschool1962]

Maroonhoo,

 

I am certainly no expert with all things FFH or even automotive but something similar happened to me on more than one occasion.

 

I have a couple questions and maybe an answer for you.

 

Did this revving happen multiple times during the day or was it just isolated to a specific trip from point A to point B.? In other words did you put the car in park at any time and then back into drive?

 

Did this happen after you may have touched the shift knob and then disappear the next time you used the vehicle?

 

The reason I ask is because....believe it or not, you may have shifted the car into Low.

 

Remember that Low can be shifted into at any speed and once you start getting over 40 it sounds like a race car but you don't have the heavy drag that you would from being in a low gear like with a conventional transmission.

 

The next time this happens if at all....take a look at the gear shift and see where it is positioned.

 

If it is in low....there's nothing to be embarrassed about. Like I said It happened to me as well. Sometimes when I shifted from Park to drive or reverse to drive or even at a stop light. It's a fine line with only 2 positions in the shift lever and if you held on to the button a just split second longer than normal or grabbed the shift lever while driving or at a stop light.....it doesn't take much and it will fall easily into Low.

 

If it happens and the vehicle is not in Low......then maybe.....and remember this is an uneducated guess.....there is a problem with the switch that controls the gear shift position in relation to the ECVT. Mine was strictly on my part.

 

Hope this helps.

Edited August 12, 2010 by oldschool1962

[Oman]

Ditto. Had the *passenger" bump the shifter to low. Didn't notice until coasting. Check the dash indicator the next time you hear it. The shifter is just a switch in the FFH. The dash will tell you what the car thinks the shifter position is in. It is possible to have the shifter appear to be in D when the switch makes the computer think it is in L.

 

Jojn

 

 

Maroonhoo,

 

I am certainly no expert with all things FFH or even automotive but something similar happened to me on more than one occasion.

 

I have a couple questions and maybe an answer for you.

 

Did this revving happen multiple times during the day or was it just isolated to a specific trip from point A to point B.? In other words did you put the car in park at any time and then back into drive?

 

Did this happen after you may have touched the shift knob and then disappear the next time you used the vehicle?

 

The reason I ask is because....believe it or not, you may have shifted the car into Low.

 

Remember that Low can be shifted into at any speed and once you start getting over 40 it sounds like a race car but you don't have the heavy drag that you would from being in a low gear like with a conventional transmission.

 

The next time this happens if at all....take a look at the gear shift and see where it is positioned.

 

If it is in low....there's nothing to be embarrassed about. Like I said It happened to me as well. Sometimes when I shifted from Park to drive or reverse to drive or even at a stop light. It's a fine line with only 2 positions in the shift lever and if you held on to the button a just split second longer than normal or grabbed the shift lever while driving or at a stop light.....it doesn't take much and it will fall easily into Low.

 

If it happens and the vehicle is not in Low......then maybe.....and remember this is an uneducated guess.....there is a problem with the switch that controls the gear shift position in relation to the ECVT. Mine was strictly on my part.

 

Hope this helps.

[maroonhoo]

Maroonhoo,

 

I am certainly no expert with all things FFH or even automotive but something similar happened to me on more than one occasion.

 

I have a couple questions and maybe an answer for you.

 

Did this revving happen multiple times during the day or was it just isolated to a specific trip from point A to point B.? In other words did you put the car in park at any time and then back into drive?

 

Did this happen after you may have touched the shift knob and then disappear the next time you used the vehicle?

 

The reason I ask is because....believe it or not, you may have shifted the car into Low.

 

Remember that Low can be shifted into at any speed and once you start getting over 40 it sounds like a race car but you don't have the heavy drag that you would from being in a low gear like with a conventional transmission.

 

The next time this happens if at all....take a look at the gear shift and see where it is positioned.

 

If it is in low....there's nothing to be embarrassed about. Like I said It happened to me as well. Sometimes when I shifted from Park to drive or reverse to drive or even at a stop light. It's a fine line with only 2 positions in the shift lever and if you held on to the button a just split second longer than normal or grabbed the shift lever while driving or at a stop light.....it doesn't take much and it will fall easily into Low.

 

If it happens and the vehicle is not in Low......then maybe.....and remember this is an uneducated guess.....there is a problem with the switch that controls the gear shift position in relation to the ECVT. Mine was strictly on my part.

 

Hope this helps.

 

Thanks Oldschool and Oman. That just might be what happened. Both times when I parked, once to run into a store and the second time to get gas, I restarted and the problem was gone, so what you're saying makes sense here. I would like to put the car in low gear, drive it, and see if I can reproduce the problem, but I'm afraid of the damage it could do to the engine and transmission if I put my car in low gear and drive it at the speeds at which I previously experienced the problem. I suppose next time I hear the revving, I'll just have to take a look at the dash and note what gear I'm in.

 

Thanks again. This is a plausible explanation, one that's far more helpful than the "dunno's" I've received from the guys at my local Ford service centers. :)

[akirby]

Thanks Oldschool and Oman. That just might be what happened. Both times when I parked, once to run into a store and the second time to get gas, I restarted and the problem was gone, so what you're saying makes sense here. I would like to put the car in low gear, drive it, and see if I can reproduce the problem, but I'm afraid of the damage it could do to the engine and transmission if I put my car in low gear and drive it at the speeds at which I previously experienced the problem. I suppose next time I hear the revving, I'll just have to take a look at the dash and note what gear I'm in.

 

Thanks again. This is a plausible explanation, one that's far more helpful than the "dunno's" I've received from the guys at my local Ford service centers. :)

 

You won't damage anything by putting in low - the computer won't allow damage. Test away!

[maroonhoo]

You won't damage anything by putting in low - the computer won't allow damage. Test away!

 

Really? I always thought that driving a car in low gear at high speeds in regular driving conditions (i.e. not particularly hilly) caused the trans or engine unnecessary wear and tear. Is that no longer so, or is what you're describing a special feature of the FFH?

[lolder]

Really? I always thought that driving a car in low gear at high speeds in regular driving conditions (i.e. not particularly hilly) caused the trans or engine unnecessary wear and tear. Is that no longer so, or is what you're describing a special feature of the FFH?

It won't hurt it. No point in doing it longer than necessary for the test. There's never any wear on this transmission. All you're doing while coasting is turning the engine faster with the transmission at essentially no fuel flow for compression braking. Go to the second display mode "Enlighten" to observe the RPM. It's higher in "L" coasting. "L" will also let you go into EV after you coast during warm up before components reach temperature as indicated by the thermometer bulb turning green in "Empower " display mode. I guess this is to limit ICE rpm when cold. After the bulb turns green, "L" does the opposite and will INHIBIT EV mode while coasting. The difference in ICE rpm between "L" and "D" is related to how much throttle you are calling for. At moderate or greater acceleration, there is no difference. At cruise at 50 mph, D yields 1400 rpm and L, 3000 rpm. If you're going down a hill in L it goes even higher as opposed to 0 rpm (EV mode) or about 1100 rpm if above 47 mph in D. This is a very clever car. Prius calls this mode "B" for braking I guess.

I'm sure this was your noise.

Edited August 13, 2010 by lolder

[maroonhoo]

I tested it and drove my car in low gear on the expressway yesterday, and I heard the same revving while coasting. I bet the car was in low gear the other two times it made the strange noises.

 

You folks on this forum are quite the clever bunch. Thanks for the help!