coasting in neutral, got a power train malfunction wrench

[Michael_vroomvroom]

This morning I was coasting in neutral for about 700-800 meters (half a mile) I guess. There's a slightly sloping stretch of road that's sometimes traffic jammed, so it's a lot more convenient to shift to neutral and just use the brake to stop and start. At the end of the stretch when I shifted to first and accelerated a little bit, I however for the first time in my one and a half years of ownership got the malfunction wrench up on the dash, and at the same time a pre-collision alert.

Car was then in some sort of limp mode, could not rev past 4,000, and some convenience functions were disabled too as I found out when I pulled over a few minutes later, uphill. Turned the car quickly off and on, but problem persisted. Drove to my destination 20 minutes away, which ironically enough was the local Ford dealer. Parked there for about 10 minutes with the engine off, and when I turned it on again in front of the delaer guy, the wrench was gone.

Anyone experienced anything similar? The local Ford dealer is only partially open at the moment (going through a slow ownership change. Can get parts there, but not much else at the moment), so they apologised for not being able to check it out with their diagnostic computer and suggested I take it to another dealer.

I had no problems on the trip back afterwards, but have not taken it to any dealer yet. "Car Scanner" (an OBD android app) showed some older minor alerts I forgot to screenshot, but nothing active.

I'm wondering if my coasting in neutral could be related to the wrench lighting up?

I found a post on another forum saying
"""
I had the limp home wrench a couple of times after a long coast in neutral uphill at high speed. In my case I had removed the back plate of the grill in front of the CAI. Coasting in neutral with a CAI can fool the MAS in that high air volume flowing into intake when car is idling at high speed. When I blocked the front of the grill with a piece of cardboard over the area I had cut out (in front of CAI) and did a coast down, the problem disappeared. Needless to say I don't do anymore high speed coast downs in neutral anymore
"""

I don't have any CAI, and I'm not sure how one coasts, especially for long, uphill, but wondering if it's just a coincidence that the wrench lit up while coasting like that, or if the ECU got confused about it? Anyone else seen/heard of that happening? Seems a bit silly if that's the case, but looking for an excuse to not having to leave it at the dealer.

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[Farkel]

This morning I was coasting in neutral for about 700-800 meters (half a mile) I guess. There's a slightly sloping stretch of road that's sometimes traffic jammed, so it's a lot more convenient to shift to neutral and just use the brake to stop and start. At the end of the stretch when I shifted to first and accelerated a little bit, I however for the first time in my one and a half years of ownership got the malfunction wrench up on the dash, and at the same time a pre-collision alert.

Car was then in some sort of limp mode, could not rev past 4,000, and some convenience functions were disabled too as I found out when I pulled over a few minutes later, uphill. Turned the car quickly off and on, but problem persisted. Drove to my destination 20 minutes away, which ironically enough was the local Ford dealer. Parked there for about 10 minutes with the engine off, and when I turned it on again in front of the delaer guy, the wrench was gone.

Anyone experienced anything similar? The local Ford dealer is only partially open at the moment (going through a slow ownership change. Can get parts there, but not much else at the moment), so they apologised for not being able to check it out with their diagnostic computer and suggested I take it to another dealer.

I had no problems on the trip back afterwards, but have not taken it to any dealer yet. "Car Scanner" (an OBD android app) showed some older minor alerts I forgot to screenshot, but nothing active.

I'm wondering if my coasting in neutral could be related to the wrench lighting up?

I found a post on another forum saying
"""
I had the limp home wrench a couple of times after a long coast in neutral uphill at high speed. In my case I had removed the back plate of the grill in front of the CAI. Coasting in neutral with a CAI can fool the MAS in that high air volume flowing into intake when car is idling at high speed. When I blocked the front of the grill with a piece of cardboard over the area I had cut out (in front of CAI) and did a coast down, the problem disappeared. Needless to say I don't do anymore high speed coast downs in neutral anymore
"""

I don't have any CAI, and I'm not sure how one coasts, especially for long, uphill, but wondering if it's just a coincidence that the wrench lit up while coasting like that, or if the ECU got confused about it? Anyone else seen/heard of that happening? Seems a bit silly if that's the case, but looking for an excuse to not having to leave it at the dealer.

I had a similar experience. I was up in the mountains and had pulled over and stopped on a downhill grade. I decided to just let it roll in neutral to get back up to speed, and the wrench light came on. I stopped, turned the car off, and when I restarted it and used the clutch/transmission to get going everything was back to normal. I haven't tried coasting like that since then, and the wrench hasn't lit up again.

 

[friedmud]

Seems about right: you’re obviously using a Mustang wrong if you don’t tear ass from 0-60

 

[Jason304]

Half the fun of driving my mustang is the rev matching down shifts to slow or come to a stop and listening to the voodoo pop and crack.
If you’re coasting, you’re doing it wrong.

 

[gadgtfreek]

I will normally cost say from 40 mph on a city street to a stop if I know the light isn't gonna change. If I think I have a shot I will run down a couple of gears just for the sound lol. Haven't gotten any issues from it.

Interesting about the uphill head. When I am coming to a stop up a hill I usually drop one gear and let it engine brake until close to traffic.

 

[Michael_vroomvroom]

Half the fun of driving my mustang is the rev matching down shifts to slow or come to a stop and listening to the voodoo pop and crack.
If you’re coasting, you’re doing it wrong.

There's not much fun in moving a few meters, stop for 5-20 seconds, either holding the clutch of shifting to neutral. Then rolling forward a few meters again, and then repeating the same 30-40 times till I get to the end of the traffic jam.

Maybe I'd enjoy it more with a Voodoo ;-)

 

[GT Pony]

I had no problems on the trip back afterwards, but have not taken it to any dealer yet. "Car Scanner" (an OBD android app) showed some older minor alerts I forgot to screenshot, but nothing active.

If there was a related trouble-code set, it would think it would have still shown up as a "history" trouble-code.

 

[Jason304]

There's not much fun in moving a few meters, stop for 5-20 seconds, either holding the clutch of shifting to neutral. Then rolling forward a few meters again, and then repeating the same 30-40 times till I get to the end of the traffic jam.

Maybe I'd enjoy it more with a Voodoo ;-)

Not too many traffic jams in rural WV

 

[br_an]

Seems about right: you’re obviously using a Mustang wrong if you don’t tear ass from 0-60

I believe it says so right in the owner's manual

 

[Laztug]

Just when I thought a manual mustang couldn't get any worse.

 

[sk47]

Hello; back before the computer monitored everything there was a potential issue with coasting in neutral. That being some transmissions did not sling gear oil around when in neutral. The main problem might be if the car was towed. I seem to recall being told to undo the drive shaft at the rear if a car was to be towed.
My guess is there are sensors which monitor things such as road speed and transmission function. Might be the computer cannot rectify the data being different than expected from sensors.

 

[friedmud]

There's not much fun in moving a few meters, stop for 5-20 seconds, either holding the clutch of shifting to neutral. Then rolling forward a few meters again, and then repeating the same 30-40 times till I get to the end of the traffic jam.

Maybe I'd enjoy it more with a Voodoo ;-)

I suspect you _would_ actually enjoy it more with a Voodoo

 

[Michael_vroomvroom]

I suspect you _would_ actually enjoy it more with a Voodoo

Ok, I'm sure I would. :-) But seems like a needless wear and tear on the clutch and/or gearbox anyway.

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