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Mechanical Over Rev. What next?

9210 Views 15 Replies 9 Participants Last post by  ccrun1800
Yesterday merging onto the freeway I managed to shift from 3rd gear to 2nd. I was at ~ 6K RPM in 3rd when I shifted. The car immediately shut off and I was able to roll over the shoulder of the freeway. I got a message on my display something about service engine. The car did not immediately re fire. After two attempts the car started up and idled fine. When driving home it was missing and stumbling and power was low. I am guessing I was in "limp mode." Once I was able to get home I pulled the positive battery cable and waited for 45 minutes. After re-connecting the battery, and starting the car it fired right up. No more CEL, no weird noises. I took the car for a 7 mile test drive and it seemed fine like nothing happened. No weird noises coming from the motor. No smoke coming from the tail pipe. I pulled the dipstick and no metal fragments. Drove it 15 miles to work today and it is running fine. Should I take it into the dealer to have them pull codes? Should I be worried? What should my next steps be? Thanks for any suggestions.
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Yesterday merging onto the freeway I managed to shift from 3rd gear to 2nd. I was at ~ 6K RPM in 3rd when I shifted. The car immediately shut off and I was able to roll over the shoulder of the freeway. I got a message on my display something about service engine. The car did not immediately re fire. After two attempts the car started up and idled fine. When driving home it was missing and stumbling and power was low. I am guessing I was in "limp mode." Once I was able to get home I pulled the positive battery cable and waited for 45 minutes. After re-connecting the battery, and starting the car it fired right up. No more CEL, no weird noises. I took the car for a 7 mile test drive and it seemed fine like nothing happened. No weird noises coming from the motor. No smoke coming from the tail pipe. I pulled the dipstick and no metal fragments. Drove it 15 miles to work today and it is running fine. Should I take it into the dealer to have them pull codes? Should I be worried? What should my next steps be? Thanks for any suggestions.
I would start with a compression test. I just put a motor in a civic SI for the same exact reason. He went down instead of up and bent a valve, we thought it would just need head work until it was apart and it looked like the valve put enough pressure on the piston to push it up against the cylinder wall and score it badly. I know Hondas will throw a "over-rev" code when that happens and take a snap shot of engine parameters, not sure about fords. He swore that the over-rev happened a few days or weeks before the car actually gave up, but who knows it took a lot of digging to figure out what really happened with that car anyways. Wish you the best of luck!
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I just came home from the Ford dealer. He ran the code scanner against my ECU. He did not find any error codes in the ECU. He also went for a spirited drive with me on the freeway. I did a few hard pulls into 6k RPM. During the drive he had his laptop connected to the OBDII port. He did not see anything out of the ordinary. He is going to take the info he gathered and call Ford tech support in Dearborn. Waiting for their response.
I just came home from the Ford dealer. He ran the code scanner against my ECU. He did not find any error codes in the ECU. He also went for a spirited drive with me on the freeway. I did a few hard pulls into 6k RPM. During the drive he had his laptop connected to the OBDII port. He did not see anything out of the ordinary. He is going to take the info he gathered and call Ford tech support in Dearborn. Waiting for their response.
I would still say for the half hour of time and 50 bucks for the compression tester rental that would be your best bet and that will take all the guess work bs out if the equation.
Compression test for sure, but unfortunately with stuff like this you just don't know. Usually the motor will blow up right away, appear fine and then out of nowhere pop, or be fine until you sell it. You're in either bucket two or three.
I am going to rent the compression tester from the local auto parts store and a bore scope. I'll take a look tomorrow. Are there any tricks for finding TDC on each cylinder? Or do I just crank the motor till the gauge stops moving?
Gas all the way clutch all the way unplug all the coils and hit the start button it will crank for like 10 seconds and stop then you can check the guage.
Just to make sure I am reading this correctly, all symptoms were resolved by disconnecting the positive battery cable?

If that is the case, checking compression is probably the worst suggestion I have ever heard.

No offense.

A loss of compression will be cause by a bent/damaged valves, failed rings or cracks/damage to the combustion chamber. None of which are repaired by removal of the positive battery cable.

And for the record, all vehicle manufactures have a DTC for excessive engine speed. P0219? I believe.

In regards to the tech contacting Ford support, he is completely wasting their time if you two could not duplicate the concern. The tech was basically saying "here is data from a perfectly running car, can you tell me what's wrong with it?"

If you can't get the issue to occur again (without shifting into 2nd at 6K) then I would say it was a freak accident and you are fine.
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If you and Ford see no codes and the engine dies later under warranty then you are all set. New engine. Otherwise trade it when the warranty is up.
I did the same thing in my car about 1500 miles ago. Knock on wood, it's been fine since then and that's with spirited daily driving and an autocross event. You're fine.
Just to make sure I am reading this correctly, all symptoms were resolved by disconnecting the positive battery cable?

If that is the case, checking compression is probably the worst suggestion I have ever heard.

No offense.

A loss of compression will be cause by a bent/damaged valves, failed rings or cracks/damage to the combustion chamber. None of which are repaired by removal of the positive battery cable.

And for the record, all vehicle manufactures have a DTC for excessive engine speed. P0219? I believe.

In regards to the tech contacting Ford support, he is completely wasting their time if you two could not duplicate the concern. The tech was basically saying "here is data from a perfectly running car, can you tell me what's wrong with it?"

If you can't get the issue to occur again (without shifting into 2nd at 6K) then I would say it was a freak accident and you are fine.
I am in the same thought process. What was worrying to me is the car went into limp mode. I did kick the clutch really fast when I realized I went into the wrong gear. I do not know the behavior of the ECU but maybe it went into protect mode, then I kicked the clutch and that is why it stalled. Once I came to a stop I was able to re-start it after 2 tries (possibly to re-learn idle??). After getting it home in limp mode I pulled the positive battery cable for 30 minutes plugged it back in and the car fired right up. No CELs, No smoke, No funny noises. Would pulling the battery cable clear a excessive engine speed code?
I am in the same thought process. What was worrying to me is the car went into limp mode. I did kick the clutch really fast when I realized I went into the wrong gear. I do not know the behavior of the ECU but maybe it went into protect mode, then I kicked the clutch and that is why it stalled. Once I came to a stop I was able to re-start it after 2 tries (possibly to re-learn idle??). After getting it home in limp mode I pulled the positive battery cable for 30 minutes plugged it back in and the car fired right up. No CELs, No smoke, No funny noises. Would pulling the battery cable clear a excessive engine speed code?
I haven't heard of the PCM stalling the engine to prevent damage, but I would not be surprised if it did. It does have a limp mode strategy referred to as FMEM (failure management effects mode). It essentially it limits throttle and fuel to prevent damage to the engine and emissions components. So that part is normal, until the PCM has determined that it is safe to go back to full capacity.

A battery disconnect should not clear a code, but anything is possible. There are two "modes" that the codes can be in, memory or on demand. On demand means that the fault is present right this second and this is a hard fault. If it is in memory, the PCM saw the fault at one point but it no longer sees the issue. When the DTC is in memory, it has to be cleared with a scan tool or go through so many drive cycles to clear on it's on.

My guess is that it didn't get a chance to set the code. Most codes require the issue to be present for at least 5 seconds at least 2 times before it trips a code. One time I was cleaning out my car and I accidentally put my floor mat on top of the gas pedal. The car shot to red line twice before I figured out what was causing it, it set a CEL but there were no codes present. So it knew that there was an issue but it didn't know what. I cleared the light with my AP and never saw it again.


If you are not experiencing any issues now then I wouldn't worry about it.

Also, if you were to check compression, disconnect the injectors rather than the coils. This prevents fuel from collecting in the combustion chamber when cranking. You can hold the gas pedal to the floor which will cause the PCM to go into clear flood mode which will shut the injectors off but it's an extra, unnecessary step.
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I haven't heard of the PCM stalling the engine to prevent damage, but I would not be surprised if it did. It does have a limp mode strategy referred to as FMEM (failure management effects mode). It essentially it limits throttle and fuel to prevent damage to the engine and emissions components. So that part is normal, until the PCM has determined that it is safe to go back to full capacity.

A battery disconnect should not clear a code, but anything is possible. There are two "modes" that the codes can be in, memory or on demand. On demand means that the fault is present right this second and this is a hard fault. If it is in memory, the PCM saw the fault at one point but it no longer sees the issue. When the DTC is in memory, it has to be cleared with a scan tool or go through so many drive cycles to clear on it's on.

My guess is that it didn't get a chance to set the code. Most codes require the issue to be present for at least 5 seconds at least 2 times before it trips a code. One time I was cleaning out my car and I accidentally put my floor mat on top of the gas pedal. The car shot to red line twice before I figured out what was causing it, it set a CEL but there were no codes present. So it knew that there was an issue but it didn't know what. I cleared the light with my AP and never saw it again.


If you are not experiencing any issues now then I wouldn't worry about it.

Also, if you were to check compression, disconnect the injectors rather than the coils. This prevents fuel from collecting in the combustion chamber when cranking. You can hold the gas pedal to the floor which will cause the PCM to go into clear flood mode which will shut the injectors off but it's an extra, unnecessary step.
I figure if I hurt the motor mechanically. I.e. Bent valve or valve slapped a piston I would be having misfires. I was going to follow Stratifieds blog instructions to perform the compression test.

Blog : How to perform a compression test on a Ford Focus ST : Stratified Automotive Controls
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I rented a borescope too. Might as well take a look while I have the plugs out. Did I mention my car has only 2500 miles on it?!
I did the same thing in my car about 1500 miles ago. Knock on wood, it's been fine since then and that's with spirited daily driving and an autocross event. You're fine.
I did one about 3000 miles ago. She threw a code but after parking her for the night it was code free in the morning. Couldn't find anything at the Dealership either so I would say no worries.
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