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Powerboost Exhaust Heat Exchanger Delete

amschind

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I have been laboring under and spreading lies. I thought that the exhaust to coolant heat exchanger in the Powerboost is part of the low-temp battery loop and was designed to make sure that the LiFePO4 battery quickly gets above freezing temperatuure so that it can be charged (i.e. used at all) in cold weather. That interpretation was WHOLLY WRONG. As I have been informed (hat tip to HammaMan), the exhaust to coolant exchanger is actually part of the high temperature loop and as such its only function is to raise the temperature of the engine coolant more quickly.

At first glance, that distinction might seem unimportant, but in terms of removing a failure prone part that has earned its own Thread Of Shame, this means that we can realistically delete the stupid thing and be done with it. Were it part of the battery management system, removing it would require us to replace its role in warming the battery because lithium batteries hate the cold, and most importantly any effort to charge one while it is below 32F will rapidly kill it. If Ford's battery management system didn't have the right failsafes from direct battery temperature monitoring and just assumed battery temp based upon other inputs (not saying that this would be a good design.....but it's Ford), there is a real risk that removing a battery heater could kill your battery. However, if the stupid thing only makes the engine heat up a bit faster, then the worst case is slightly increased engine wear from slower oil warmup in cold weather. We know that a 3.5L Ecoboost doesn't require this part, so the engine can clearly run well with baseline auto start-stop. If wear really is an issue, then preemptive fix for faster wear is to change engine idle behavior in cold weather with a tune or simply using your app to warm the truck up before you drive anywhere (since it will automatically idle to run the heater in cold weather).

Bottom line the consequences for this mod are 1) hypothetical and 2) have solutions which are being actively engineered for and deployed on the most popular engine in the most popular truck in the world. I think that leads us to the question of: how?

The three steps are:
1) shunt the inlet coolant line to the outlet coolant line. Ideally, you have a double SS connector and leave plenty of hose attached to the exchanger so that it's easy to reuse/reinstall.
2) remove the exchanger from the exhaust path. This is simple for an exhaust shop, but they are VERY nervous about touching these things. That may make #3 easier to do first:
3) develop a spud connector with appropriate resistors which can attach to the controller wires to avoid angering the ECM. In some ways, just having the unit sitting on the truck without coolant is simpler, but that risks ruining the exhanger if the system directs exhaust through it while there is no coolant flow. That wouldn't hurt the truck (since the coolant loop is no longer involved), but it would likely kill an expensive part that you might want to restore some day or could at least sell.

My aims with all of this are twofold:
1) get a full custom exhaust
2) preemptively remove a failure point. I was driving through middle of nowhere West Texas last night, and it would've been pretty miserable to find out via an overheat message that this exchanger had distributed my coolant along 100 miles blacktop. It would need to have a pretty important job to justify that risk.....and I have learned that it provide nearly zero benefit in return for the threat of stranding us.

So what say you?
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HammaMan

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It's a lithium ion that self-heats real fast as it's always doing ~22c charging and discharging.

You're going to have to find a way to provide a warm signal to the system on warmup.

There may be some things buried that forscan can change so the truck ignores the values. Almost anything can be deleted or added in one form or another.
 
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amschind

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You're going to have to find a way to provide a warm signal to the system on warmup.
I think the specifics of "warm signal" are going to be the heart of the matter. More to the point, is there a sensor within the exchanger or is it simply a motor that receives commands in the form of DC current? In the former case, I'll need to disable whatever setting says "listen for the sensor (that is no longer present)"; in the latter case, all I need is a plug with resistors so that the DC signal sees the expected resistance instead of an open circuit. I will try to look at the codes that folks are getting on the exchanger failure thread, as my guess is that deliberately removing the whole thing will generate a similar PCM code.
 

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I think the specifics of "warm signal" are going to be the heart of the matter. More to the point, is there a sensor within the exchanger or is it simply a motor that receives commands in the form of DC current? In the former case, I'll need to disable whatever setting says "listen for the sensor (that is no longer present)"; in the latter case, all I need is a plug with resistors so that the DC signal sees the expected resistance instead of an open circuit. I will try to look at the codes that folks are getting on the exchanger failure thread, as my guess is that deliberately removing the whole thing will generate a similar PCM code.
Well when the thing leaks, it throws a code some how. What do you think will happen when it's missing? There's valves and temp sensors on that loop that keep an eye on it. I believe there's another 3 or 4 way valve under the hood that interacts with it too.
 
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amschind

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Well when the thing leaks, it throws a code some how. What do you think will happen when it's missing? There's valves and temp sensors on that loop that keep an eye on it. I believe there's another 3 or 4 way valve under the hood that interacts with it too.
Agree; keeping the PCM happy will be the hard part. Replumbing the coolant lines is easy and removing the exchanger itself should take 1 minute with a sawzall.

With regard to the multi-way valve in the engine bay, I'm not sure that it would be worthwhile to fight with that thing. 1) it's almost certainly complex and 2) the amount of effort required to change that nets you what.....a little less wasted energy as the water pump pushes coolant through the shunted loop? You could drive the truck for 20 years on 93 Octane and put 500k miles on it and still not even recoup the cost of the time pondering that solution. The piece that I think would need to be addressed is the delta-T sensor. I wonder if you can command the truck to ignore that value or set the expected delta T to zero?
 

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HammaMan

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Agree; keeping the PCM happy will be the hard part. Replumbing the coolant lines is easy and removing the exchanger itself should take 1 minute with a sawzall.

With regard to the multi-way valve in the engine bay, I'm not sure that it would be worthwhile to fight with that thing. 1) it's almost certainly complex and 2) the amount of effort required to change that nets you what.....a little less wasted energy as the water pump pushes coolant through the shunted loop? You could drive the truck for 20 years on 93 Octane and put 500k miles on it and still not even recoup the cost of the time pondering that solution. The piece that I think would need to be addressed is the delta-T sensor. I wonder if you can command the truck to ignore that value or set the expected delta T to zero?
Dunno. I enjoy my fast instant heat 🤷‍♂️ :)
 

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Don't let me discourage you!
I would love for you to come up with a successful bypass or delete.


But the exhaust heat exchanger wouldn't be such a weak point if the material choices were altered in the direction of "robust" under heat?


I have some spares of the most vulnerable leaking source. $5 each part:

Ford F-150 Powerboost Exhaust Heat Exchanger Delete 20230317_171909




The 2 temp sensors are circled red:

Ford F-150 Powerboost Exhaust Heat Exchanger Delete Screenshot_20230329_203537_OneDrive




Notice for the 6th DTC listed regarding the heat exchanger. It includes a reference for the PCM measuring the temperature difference between inlet/outlet and has an expected range

Ford F-150 Powerboost Exhaust Heat Exchanger Delete Screenshot_20230329_204545_OneDrive
 
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amschind

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But the exhaust heat exchanger wouldn't be such a weak point if the material choices were altered in the direction of "robust" under heat?
Yes, that would help, but I think that the more fundamental challenge is integrating intermittent coolant (water AND ethylene glycol)flow + electronics with a heat source that will damage both. Frankly, given the innate challenges, I am amazed that the exchanger works as well as it does. This exchanger is eerily similar to a boiler, and boilers are EXCEPTIONALLY dangerous devices. Our current best practices make them seem safe, but that knowledge is built upon a pile of horribly scalded corpses. I don't think that the tiny heat exchanger is going to fail and hurt anyone, but working flawlessly for 200k miles is an uphill climb even if you milled it out of inconel.

Thanks so much for the data. The problem is as bad as I had feared: you have to spoof or command the system to ignore a position sensor and temperature sensors.

There is a potential solution if the Forscan workaround doesn't work. You don't want the sensors integrated into the coolant loop because then your crazy spoofing mods pose the same hazard or worse as the original part. Your tools are 12V signal that is likely constant when there is supposed to be delta T and two relatively small sensors. If you could just weld a small box onto the exhaust pipe with fittings for the sensors such that the temperature is near coolant temp, and then epoxy a resistor the downstream sensor probe wired to the 12V turnon signal, that could fix the issues (except the position issue). You'd have to fiddle with it A LOT to get it working.

Another question:
What are the consequences of just living with the DTC codes? Would these be show-stoppers for getting an inspection done? Or put another way, since the codes would likely only show up in cold weather, could you just clear them and get the truck inspected in the summer?
 
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EcoOrBoost

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Welp, my pb with 6k miles is currently throwing the CEL and DTC P2C23. No drips on the garage floor. Dealer looked it over and ordered the replacement, says we’re two weeks out for the replacement part and I’m good to drive it while we wait.

Admittedly I don’t really understand the design. Is there any way that coolant can leak into the exhaust stream? This winter I’ve noticed that my pb seems to evap a lot more than previous engines. Any previous vehicles I’ve owned only exhibit exhaust steam for maybe 5-10 minutes until the engine is warm, but with all the engine cycling my pb seems to never quite stop with visible steam in the exhaust in the cold.
 
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amschind

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I'd be thrilled the buy the busted part from you.
 

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EricR

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I have been laboring under and spreading lies. I thought that the exhaust to coolant heat exchanger in the Powerboost is part of the low-temp battery loop and was designed to make sure that the LiFePO4 battery quickly gets above freezing temperatuure so that it can be charged (i.e. used at all) in cold weather. That interpretation was WHOLLY WRONG. As I have been informed (hat tip to HammaMan), the exhaust to coolant exchanger is actually part of the high temperature loop and as such its only function is to raise the temperature of the engine coolant more quickly.

At first glance, that distinction might seem unimportant, but in terms of removing a failure prone part that has earned its own Thread Of Shame, this means that we can realistically delete the stupid thing and be done with it. Were it part of the battery management system, removing it would require us to replace its role in warming the battery because lithium batteries hate the cold, and most importantly any effort to charge one while it is below 32F will rapidly kill it. If Ford's battery management system didn't have the right failsafes from direct battery temperature monitoring and just assumed battery temp based upon other inputs (not saying that this would be a good design.....but it's Ford), there is a real risk that removing a battery heater could kill your battery. However, if the stupid thing only makes the engine heat up a bit faster, then the worst case is slightly increased engine wear from slower oil warmup in cold weather. We know that a 3.5L Ecoboost doesn't require this part, so the engine can clearly run well with baseline auto start-stop. If wear really is an issue, then preemptive fix for faster wear is to change engine idle behavior in cold weather with a tune or simply using your app to warm the truck up before you drive anywhere (since it will automatically idle to run the heater in cold weather).

Bottom line the consequences for this mod are 1) hypothetical and 2) have solutions which are being actively engineered for and deployed on the most popular engine in the most popular truck in the world. I think that leads us to the question of: how?

The three steps are:
1) shunt the inlet coolant line to the outlet coolant line. Ideally, you have a double SS connector and leave plenty of hose attached to the exchanger so that it's easy to reuse/reinstall.
2) remove the exchanger from the exhaust path. This is simple for an exhaust shop, but they are VERY nervous about touching these things. That may make #3 easier to do first:
3) develop a spud connector with appropriate resistors which can attach to the controller wires to avoid angering the ECM. In some ways, just having the unit sitting on the truck without coolant is simpler, but that risks ruining the exhanger if the system directs exhaust through it while there is no coolant flow. That wouldn't hurt the truck (since the coolant loop is no longer involved), but it would likely kill an expensive part that you might want to restore some day or could at least sell.

My aims with all of this are twofold:
1) get a full custom exhaust
2) preemptively remove a failure point. I was driving through middle of nowhere West Texas last night, and it would've been pretty miserable to find out via an overheat message that this exchanger had distributed my coolant along 100 miles blacktop. It would need to have a pretty important job to justify that risk.....and I have learned that it provide nearly zero benefit in return for the threat of stranding us.

So what say you?
Are you looking to eliminate the radiator return line as well? They have left many a motorist abandoned too.

How about just driving and enjoying our trucks?
 
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amschind

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Are you looking to eliminate the radiator return line as well? They have left many a motorist abandoned too.

How about just driving and enjoying our trucks?
I haven't seen the failure reports on it, but if it fails that often then yes. Which section of piping is it? Globally, the factors that influence the decision to replace an owned, installed and functional part are cost and benefit. As an example, I'd love to have forged, ceramic plated pistons. The cost benefit ratio says that to gain ANY measurable benefit from that mod, I'd have to first increase boost to the point that reliability and longevity BOTH suffer quite a bit. Further, disassembly and reassembly of the entire engine is "expensive".

I'm guessing that this tube is a plastic part under the upper manifold. If it fails that often, a better aftermarket option is available, and install only requires upper manifold removal, then yes, replacement might be worthwhile.

I hope that helps.
 

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The tube is replaceable without disassembling anything prior.

A forum member has already done the self repair and stated that a mirror or cell phone picture can reveal the little torque keeper screw. Remove it and twist-unlock the tube.
 
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amschind

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The tube is replaceable without disassembling anything prior.

A forum member has already done the self repair and stated that a mirror or cell phone picture can reveal the little torque keeper screw. Remove it and twist-unlock the tube.
I'm referencing the coolant return line in the post that I quoted.....I had assumed that it's a separate piece unrelated to the plastic elbow that you bought for the heat exchanger (except that both apparently break too often). Which part are you talking about? If it's another failure prone part that's easy to swap, I bet that it deserves its own thread (or already has one?).
 
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amschind

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So, new thoughts on preventing codes:
1) the sensors are all analog.
2) you have a 12V signal from the control wire whenever the T2 sensor is supposed to read hotter than T1. This might be hard.
3) you have a 12V signal from the control wire whenever the valve position sensor is supposed to read on

The sensors aren't sending back digital data; they are just variable resistors sending back different voltages based upon the measured quantity. So, if we measure the expected resistance in the various states, we can mimic that with resistors. For the values that are supposed to change (position sensor and T2 sensor), we have a 12V signal whenever those values are expected to be different. This means that if we are willing to cut wires (which is easy to reverse if needed), we can use resistors and SSRs to make a simple circuit which will mimic the position sensor and control circuit resistance. The temp sensors may be tougher to get right because they may throw codes if they don't detect a steady change in values consistent with changing coolant temperature. However, if those sensors are just left in place in the coolant loop, they will only throw codes if the valve is engaging. The simple expedient may just be to clear codes, drive a bit and get the truck inspected in the summer (when the temp sensors are blissfully ignorant).

The required data are the resistance across the control circuit wires and the ON and OFF voltages for the position sensor. With these, you would only need 3 resistors and a 12V DC-DC SSR to make a spud. In this case, the circuit would have a resistor between the control wires to replicate that measured resistance AND a wire from the positive to the GATE terminal on the SSR. The position sensor wires would have two resistors in parallel, R1 and R2. The R1 resistor would be always in the circuit to mimic the OFF voltage, but the + sensor wire would connect to the SOURCE terminal on the SSR and the DRAIN terminal to R2 (which is always wired to the negative position sensor wire). In essence, R2 would normally be excluded from the circuit by the SSR UNLESS the SSR GATE wire received a 12V signal from the control wire. When that signal closed the relay, current would also flow to R2, such that R2 would now be in parallel with R1, thus dropping the overall circuit resistance to the ON voltage.

This assumes that the position sensor voltage increases when it's in the ON position, but the circuit is still simple even if it's the opposite. Point being, this should be really easy to make and would require 1x 12V DC-DC SSR, 3 resistors and less than 20 total solder joints (and only 4 if you got the spud premade). Returning it to stock would only involve soldering the wires back onto the stock part.

EDITED FOR CLARITY.
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