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Hit brakes and engine revs...two days later total engine failure

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First time post here...and it's long. :) While on a road trip with my 6 kids, I had a brake issue with my 2016 Ford Transit. The first time it happened, I was driving about 55 mph, hit the brakes and the engine revved. I pumped the brakes, engine stopped revving. Honestly thought I did something wrong. Same thing happened again two days later. I stopped and cleaned the sensors hoping that would resolve the issue. The next day the same thing happened making it hard to stop. I went straight to Ford and had two Ford dealerships tell me the vehicle was fine. Brakes were checked and was told no problems. I asked if it could be a leak in brake booster and was told no. No lights were coming on. I took the van to Les Schwab and was told the same thing. Unsure what to do, my brother came to the rescue and took the van. He started driving it home to California from Colorado. I rented an RV and continued our road trip. 80 miles later, the engine on the van made a loud bang and ceased. No engine lights. My brother said the engine started having acceleration problems so he stopped and checked all of the fluids. Everything was fine and engine was not overheated. But, complete engine failure at 79,000 miles. This was July. Since then, we paid to have a new engine installed. My husband flew out to pick up the van and new engine started having problems. He had to fly back home. Ford has said that the new engine is bad so they are paying for rental car and getting another new engine installed. Still do not have van. It's been three months. My concern is something else is going on...just seems extremely strange. I am still worried about the braking and revving bit and wonder if anyone else has had a similar issue.
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Other vehicles that have that same engine and controls would be same year F-150 and Explorer, Flex. You might search those forums to see if they are similar (brake /overrev) unintended acceleration events and rotating assembly failures with out warning.
 
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2019 HR Cargo Oxford White 148 wb 3.7L
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Great move to get it into neutral! It happened so fast the first time my mind was still saying "this isn't really happening". You're not crazy, or we both are ;)
I might add, don't shut off the engine until you are out of traffic, you don't want to lose power steering and brakes when fecal matter is hitting the rotary impeller.
 

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I'm not sure how the power brakes work on your van but if it has a vacuum power brake booster, that might explain the engine revving if the booster has a hole in the rubber diaphragm. If it did, that would allow un-metered air into the intake manifold. The computer would try to compensate for the "false air" but could only do so much. It would cause a lean fuel mixture and could damage the engine. I'm not sure how the booster on your van works but that could be your problem.
This is my guess. I've seen an F-150 with a bad brake booster do the same thing. It would also explain the blown engine, and the second blown engine.
 

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This is weird, scary and doesn't make much sense.

I can see how a severe air leak could cause the motor to increase its revs but not by that much and not enough to cause the vehicle to overwhelm its brakes. The volume of air leaking and the ECU mixture compensation would tap out around +10% of load.

I could see how a false signal to an electronic throttle body would cause the engine to accelerate hard with no throttle pedal input.

However, in either event the ECU's over-rev and other protection systems should stop the 3.7 non-turbo motor form revving to the point where it throws a rod.

Thrown rods are known on turbo motors if they run lean and hot. It causes severe knock and rod failure more often than not. However, knock is typically much less catastrophic on NA motors, especially ones with sub 200,000 miles on them.
 

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Another mention of leaking brake booster causing engine revs.

 

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When my Transit was new it would drop from fifth gear into second gear over reving the heck out of the engine, And scaring the **** out of me.
It was later decided on this forum that this is normal while the TCM learns shiftpoints to match your driving style.

Just a example of how the Transit sometimes over revs.
 

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I don't think a booster can self heal for the other times in between the symptom where it did not over rev on braking. That engine is a throttle by wire system. It is possible that something was ingested that might of temporarily "stuck" the throttle plates open. I don't think that is likely for repeated events not sequential. Parts shedding indicates extreme over-rev. It is an un-pleasant Mystery. I do think problems with a replacement engine will be traced to some form of installation problem. Especially if the symptoms of problems are different on the replacement. I think Ford would not pay for a brand new engine, even with a FMC extended warranty, Unless they knew what the root cause of the original failure was. If you were experiencing similar symptoms as you did with the original engine , Then you gotta find the ROOT cause. If they are different drivability symptoms then I believe it is on the repairing dealer.

There was an issue with the T1N Sprinter OM612 and OM647 intake system where a plastic coupling would develop a crack on a seam between the turbo and the manifold. Initially that crack would NOT open up until the plastic got hot enough and the boost pressure was high enough (accelerating, going up a steep hill, etc) and subsequently dump the boost pressure. This would throw NO CODES and was a head-scratcher for quite a while among owners. Once identified, it became "common knowledge" through a forum like this one; a replacement part (Dorman) was installed and it never happened again.

SO, I wonder if a similar phenomenon could happen to some part of the vacuum system on the Transit? The hole or seam doesn't open up except under certain conditions, and the system loses vacuum. It might be something in particular to THIS individual Transit, and not a widespread issue. Something like a nicked hose or a rock cracked a hard plastic fitting.
 
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Thanks for your reply. This makes a lot of sense. The three places I took the van to have them check it out all said if the brake booster was bad or had a leak, then the brakes wouldn't work well. The brakes worked fine, they did not hit the floor. They were just losing the battle when the engine was revving at the same time. My van does have a vacuum power brake booster.
The booster could work fine (most of the time) and still have a torn diaphragm. If there is a hole in the booster, the brakes would still work, you'd just lose the power brake assist (or some degree of assist) when the torn spot opened up. That could make it harder to stop an over revving engine. If the booster was the issue, the brakes would not "go to the floor". What you've described sure sounds like a bad booster to me. See if the brake booster holds a vacuum using a vacuum pump and while testing it, pump the brakes. Pumping the brakes may expose a torn spot in the diaphragm. I owned my own 10 bay shop and was an ASE Master Tech. Just because 3 "mechanics" say the booster is good, I wouldn't bet the farm that it is! Been there done that!!!
 

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Use this link:
iATN Auto Pro Repair Shops
Auto repair shops that are members of the i-atn (international automotive technicians network) can post your vehicles problem and an email will be sent out to thousands of Techs around the world that know your vehicle. Those techs will read that email and respond to that shop. We solved many problems that way. Just find a shop that is a member of the i-atn and has a ASE Master Tech on staff.
 

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If I remember right, "high and hard" brake pedal means it's not getting vacuum to help the boost?
 
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I just can't see how:
1) a leak in the brake booster could give enough airflow to make a meaningful boost in power and
2) how the ECU could deliver enough fuel from a trim table to match the additional airflow - sufficient to deliver increased power at a level that could overwhelm the brakes.

I'd go a step further - I don't see how a 3.7NA could deliver enough power at WOT to overwhelm a full and hard application of the brakes.

I can absolutely see an error in the transmission controller causing it to downshift too far and/or too long, under hard braking to cause an over-rev capable of throwing a rod - then or shortly after. This is exactly how I destroyed the motor in my track toy - only the fault in the transmission controller was me :oops:
 

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Ok, maybe it's not the brake system as a CAUSE, but a SYMPTOM of the same thing that made the engine rev. That might lead back to corroded wiring connector where the water drips on it playing havoc with the ECU.
 

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Looks like OLD MAD remembers the CBS unintended acceleration fake story from 1978 when They ERRONIOUSLY and with CULPABILITY accused Audi of being the culprit Of BUILDING monstrous child killing 5 cylinder front wheel drive sedans that were FRANENSTEIN Machines. I think SB is on the track. However we shall never really know.
 

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First time post here...and it's long. :) While on a road trip with my 6 kids, I had a brake issue with my 2016 Ford Transit. The first time it happened, I was driving about 55 mph, hit the brakes and the engine revved. I pumped the brakes, engine stopped revving. Honestly thought I did something wrong. Same thing happened again two days later. I stopped and cleaned the sensors hoping that would resolve the issue. The next day the same thing happened making it hard to stop. I went straight to Ford and had two Ford dealerships tell me the vehicle was fine. Brakes were checked and was told no problems. I asked if it could be a leak in brake booster and was told no. No lights were coming on. I took the van to Les Schwab and was told the same thing. Unsure what to do, my brother came to the rescue and took the van. He started driving it home to California from Colorado. I rented an RV and continued our road trip. 80 miles later, the engine on the van made a loud bang and ceased. No engine lights. My brother said the engine started having acceleration problems so he stopped and checked all of the fluids. Everything was fine and engine was not overheated. But, complete engine failure at 79,000 miles. This was July. Since then, we paid to have a new engine installed. My husband flew out to pick up the van and new engine started having problems. He had to fly back home. Ford has said that the new engine is bad so they are paying for rental car and getting another new engine installed. Still do not have van. It's been three months. My concern is something else is going on...just seems extremely strange. I am still worried about the braking and revving bit and wonder if anyone else has had a similar issue.
A few of us are are trying and struggling to figure this out. I don't meant to be rude but when you say the engine revved when you hit the brakes are you sure that the revving wasn't just the normal downshifting that happens under hard braking (especially in Tow/Haul). Its supposed to do that but then upshift if the revs go high enough to reach the shift point.

OR

Do you mean that when you hit the brakes, the vehicle accelerated? This is the scenario that we are struggling with as the brakes on a Transit should be able to bring the vehicle to a full stop even with the accelerator deliberately pressed to the floor. The motor, even at WOT should not be capable of overwhelming the brakes when fully applied. If this is the case, some info on how hard it was accelerating, how hard you were braking and if the brakes were able to stop the vehicle etc., could eliminate some of the potential culprits.
 

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When my Transit was new it would drop from fifth gear into second gear over reving the heck out of the engine, And scaring the **** out of me.
It was later decided on this forum that this is normal while the TCM learns shiftpoints to match your driving style.

Just a example of how the Transit sometimes over revs.
Mine still does if I'm in Tow/Haul - its a design feature to add engine braking when stopping hard or descending a steep incline. It allows the motor to run up to ~6,000 RPM, which sounds terrible but is well within the safe operating limits.

Even when not in Tow/Haul mine downshifts and adds engine braking whenever I exit a freeway at speed and then brake late hard down the exit ramp - because I forgot I'm in a truck and not in my track toy lol..
 

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Mine still does if I'm in Tow/Haul - its a design feature to add engine braking when stopping hard or descending a steep incline. It allows the motor to run up to ~6,000 RPM, which sounds terrible but is well within the safe operating limits.

Even when not in Tow/Haul mine downshifts and adds engine braking whenever I exit a freeway at speed and then brake late hard down the exit ramp - because I forgot I'm in a truck and not in my track toy lol..
I have a base model Transit with few options, It did it twice and the only time I remember was when I was attempting to pass someone doing 30 mph in a 45 mph zone. I gunned it and it downshifted at the same time.
New to the Ecoboost and hot rodding it somewhere where there was no need for it.
 

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I've had something like this happen, but not with a Transit. My Land Rover occasionally wants to accelerate when I lightly tap the brake, but if I whomp on the brake the car stops.I always thought maybe my size 15 boots and loss of feeling from Peripheral Neuropathy were causing me to push both brake and accelerator at the same time. Now you have me suspecting a problem so I'll run it by my service folks.
 

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If the revving is actually downshifting (mine seems to jump 2-3 gears in cruise when I hit a hill, the roar and RPM spike makes me tap the brakes to get it OUT of cruise...), then we're back to a problem with the TCM. Pure speculation, but maybe there's some crossed signals and it goes into "hill assist" while moving, resulting in engine torque with nowhere to output it.
 
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