2.5 Hybrid: P0811 code OBD2

[stick]

Great thread! exactly why I am on these forums (one for my wrangler 4xe as well). really appreciate the followup on the repair and posting of the parts/labor. I expect my maverick hybrid this week and now know what to look for. I will be soft on it for awhile to allow any oils be consumed. I have a vw gli tuned to a torque significantly above the clutch capacity and thought I would be replacing it quickly. 3 years in on the same clutch, but have had a couple 'glazing' events that resulting the car clutch slipping at the slightest acceleration and it has always worked back up to normal operation over a few weeks. so dont panic out there! If mine slips, I plan on driving it easy for a few weeks, maybe try a bedding event and see where it ends up. If that doesnt fix then I will take in it. In general, I like to avoid such a drastic tear down so early as now we are counting on the dealership not to introduce some new issue through 'out of process' work standards (ie; controlled factory install devices vs. hand wrenches at the dealership)

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[mav47]

3,800-mile update and I'm linking @Ford Motor Company

Looks like the problem is indeed gone!

At ANY engine load, there's no clutch slip anymore, the P0811 CEL did not reappear, and I have not noticed a power cap at 75%. The driveline seems to work as it should and all is well.

This leads me to conclude that Hybrid owners who notice clutch slippage under high engine loads, and maybe get a P0811 CEL might do well to be patient, and try a few full-throttle runs to enable the clutch friction surfaces to fully bed themselves in. After that, the clutch will work as designed.

This procedure worked on mine, and may well work on all Hybrids with this problem.

Ford will likely update this clutch a bit, or possibly change the installation procedure to prevent this slippage problem from occurring on future Hybrids. I trust they'll come up with a solution.

 

[wax87]

All the service department said was that it was a "clutch slippage". I'm not mechanically savy but I don't think the Maverick hybrid has a clutch? They are replacing the engine damper. It sounds like they are not sure what's causing it and just doing what Ford told them too.

It has to be an oil leakage from the engine getting into the CVT. Engine oil would have VERY different properties than what is needed in the CVT

 

[casanewt]

Following. I had the CEL pop up yesterday on the highway after a roll-on pass from about 70 to 85 MPH. I'll keep an eye on it and do some acceleration tests to see if mine beds in a bit as well. I did go ahead and schedule a dealer visit, but it's a few weeks out. Thanks for all the input on this thread!

 

[MakinDoForNow]

Ok, I've been putting miles on my truck (now at 2,600) and taking it easy. I am waiting to see if Ford comes up with a solution of some kind.

But today, I thought I would test to see if the P0811 fault code would come up again. So I did a few full-throttle passes on the freeway to see if it would trigger.

On the first pass initially the engine speed increased (as you would expect), but suddenly the RPMs jumped up very quickly. I did what you would do when something unexpected happens: I let off the throttle. The sudden RPM increase actually felt as if you had a failing clutch in a manual transmission when under load it suddenly starts slipping and increases rpm.

However: I could not repeat this behavior: It only did it once, and only on the first run. Even a couple more full-throttle starts did not trigger it. I did notice that the power meter did not go much above 75% something I'd like to figure out whether that's normal (it may well be).

And today these full-throttle passes did NOT turn on the check engine light either.

Either way: I remember noticing the same unexpected RPM jump a few weeks back when I stepped on it and got my first P0811 code and corresponding check engine light.

Here's a theory: Maybe that safety clutch/damper between ICE and HF45 transaxle slips too soon causing that sudden rpm increase on the ICE that I noticed, and the friction heat generated expands the clutch or heats up the friction material just enough that it doesn't slip a second time?

I'll try it a few more times in the coming days, and see if I can make it do it again. If so, and I keep the throttle on, it may instantly trigger the P0811 code which could be a good indication of where the 2.5 Hybrid P0811 problem lies.

Or consider that the computer has detected ("learned") the load limit under what conditions the damper activates and is operating the vehicle as close as it can to what you are asking but not enough to cause the damper to activate.

 

[mav47]

Bad news:

The problem has returned

Now at a little over 6,000 miles on the odometer, under brisk acceleration (above 80% power) the clutch clearly was slipping again, the engine ECU promptly reduced available power, but it also lit the CEL, undoubtedly with the same P0811 code. And engine power was reduced to 70% again.

CEL went out after a day, and then when stepping on it, I noticed the clutch slip again, ECU power reduction promptly kicked in, but the CEL didn't light this time.

It basically means that "bedding in" the friction surfaces did not fix the issue completely, and it looks like a clutch/damper replacement will be needed. It seemed to be ok for a few thousand miles so I had thought it was fixed. It clearly is not.

I'll drop it off tomorrow at the dealer and hear what they say.

 

[MakinDoForNow]

Ma

kindof, but harmonic balance is for the belt driven stuff on the front of the engine. Damper protects what the engine is connected to. Because that is where all the power is going, much more heavy duty

Maybe think of it more like a physical instead of hydraulic (yes both are physical but different) torque converter. I expect the computer will detect the slippage and "learn" to adjust the fuel flow and timing of the sparks to give max torque increase possible without the slippage occuring. Yet another thing for computer to relearn just like it did when you first got hybrid. Possibly also when computer is reflashed or when 12v battery goes dead. I would hope that there is a 5-10 year life coin battery for the data stored from the learning.

 

[MakinDoForNow]

Bad news:

The problem has returned

Now at a little over 6,000 miles on the odometer, under brisk acceleration (above 80% power) the clutch clearly was slipping again, the engine ECU promptly reduced available power, but it also lit the CEL, undoubtedly with the same P0811 code. And engine power was reduced to 70% again.

CEL went out after a day, and then when stepping on it, I noticed the clutch slip again, ECU power reduction promptly kicked in, but the CEL didn't light this time.

It basically means that "bedding in" the friction surfaces did not fix the issue completely, and it looks like a clutch/damper replacement will be needed. It seemed to be ok for a few thousand miles so I had thought it was fixed. It clearly is not.

I'll drop it off tomorrow at the dealer and hear what they say.

I will consider that the damper is designed to slip and it happened and you noticed that the slippage was in normal expected parameters and was not severe enough to turn on the light and require examination by Ford.

 

[mav47]

I will consider that the damper is designed to slip and it happened and you noticed that the slippage was in normal expected parameters and was not severe enough to turn on the light and require examination by Ford.

If there is sufficient slip in that clutch for the ECU (or PCM) to reduce power to 70% for a few start/stop engine cycles, but not enough to set the Check Engine Light, that still means something is not right of course.

I took it to the local Ford dealer and they had it for over a week. They couldn't replicate the issue, I think they put about ten miles on the truck over a few tries, so I'm sure it was basically with a fairly "cold" driveline. They told me that they had lots of techs out with COVID at the time, so I'm sure the timing for them dealing with this wasn't great.

I picked up the truck again, and did a few full-throttle 0-60s (with video recording at the same time): all was ok. Go figure. As I am doing these tests, I now video record what happens on the dash power gauge, so I can document what's happening.

Maybe that clutch/damper will only slip when the driveline is at operating temperature with a high ambient temperature to make it all nice and toasty. I have been busy with some other projects, so I haven't wanted to "deal with any additional testing" and have simply been driving the truck. But maybe this week I'll do a few full-throttle runs when it's hot out, and will document with video what's happening, if anything.

Some general thoughts on "self-learning" of PCM or ECU modules:

People possibly overestimate how much actual "self-learning" is going on in the current generation of these electronic systems. There probably is a level of self-learning in various ongoing processes like instance fuel mapping, etc. but simple things like "how much slippage is acceptable" (less than X%) and what to do about it (reduce power to 70%) are much more likely controlled with FIXED thresholds and actions set by the engineering team during development.

As more "self-learning" input variables are introduced into a system, things get exponentially more complex with a FAR greater chance of unexpected outcomes. I'm pretty sure Ford is aware of all that and likely wouldn't complicate things when not strictly needed. At least, that's my hope!

Either way: I'll report back when I have some more data on this issue with my Maverick.

But overall I really like my little truck. It is a comfortable commuter returning 39mpg overall with 90% SoCal freeway miles. Awesome!

 

[casanewt]

New incident for me on a recent road trip. I had the check engine light activate once on me back in May when I was on the interstate with cruise set around 75 MPH and I hit the accelerator to go around someone. Just the Yellow/Orange light and it disappeared a day later. On this last trip, same scenario, but the vehicle threw a RED powertrain failure light and went into limp mode. The dash instructed me to pull over when safely possible. Power to accessories(but not HVAC) was on, but drivetrain was not functioning. Luckily, once I got over to the shoulder, I was able to reset the vehicle by doing a complete shutdown of the vehicle. It took a couple of tries, but it came back to life. We were able to continue on with no issues at all other than a Yellow/Orange engine light that disappeared in a couple of hours of continued interstate driving. It was a crazy scenario though and a step up from the first incident. @Ford Motor Company

 

[shiftsport]

My XLT Hybrid just returned from Ford service where I got the dreaded P0811 code about 2 weeks ago. Service was about 1 week and had to R&R engine/transmission to replace transaxle damper.

 

[casanewt]

My XLT Hybrid just returned from Ford service where I got the dreaded P0811 code about 2 weeks ago. Service was about 1 week and had to R&R engine/transmission to replace transaxle damper.

Wow. Do you have any more details on your specific experiences?

 

[casanewt]

the vehicle threw a RED powertrain failure light and went into limp mode. The dash instructed me to pull over when safely possible. Power to accessories(but not HVAC) was on, but drivetrain was not functioning. Luckily, once I got over to the shoulder, I was able to reset the vehicle by doing a complete shutdown of the vehicle. It took a couple of tries, but it came back to life. We were able to continue on with no issues at all other than a Yellow/Orange engine light that disappeared in a couple of hours of continued interstate driving. It was a crazy scenario though and a step up from the first incident. @Ford Motor Company

So this happened again yesterday after a simple pass on a 2 lane highway.

 

[MakinDoForNow]

Ma

Maybe think of it more like a physical instead of hydraulic (yes both are physical but different) torque converter. I expect the computer will detect the slippage and "learn" to adjust the fuel flow and timing of the sparks to give max torque increase possible without the slippage occuring. Yet another thing for computer to relearn just like it did when you first got hybrid. Possibly also when computer is reflashed or when 12v battery goes dead. I would hope that there is a 5-10 year life coin battery for the data stored from the learning.

I read somewhere, manual I believe, relearn occurs if negative cable disconnected from 12v battery. So can we place 12v temp battery in parallel when swapping battery? But couldn't be done most of time.

 

[Egz]

Just had it pop up on mine a tad over 10k miles. 70mph section of highway, uphill, passing slowpokes. I just cleared it for now, and going to see if it comes back. Going to watch the power meter too to see if it has full range.

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