FFH Warm Up Stages

[hybridbear]

This information is adapted from information published on the Prius Warm Up Stages. Our cars operate much the same. This information should help us all understand the cars better and get better gas mileage.

 

Over time I will edit this post as I learn more about how the FFH works.

 

Stage 0 (S0): Car begins in EV mode. Certain HVAC settings may cause the ICE to immediately start instead of allowing EV operation. The FFH will stay in S0 until the power demand from your acceleration exceeds the power that can be provided by the HVB and the electric motor.

 

Stage 1a (S1a): Initial warm-up with late ignition timing and diminished engine power.

Engine-off at stops: No.

Engine-off gliding: No.

EV Mode: No.

 

Unless the ICE is already quite warm (above 60 or 65 C it appears), S1a begins at the conclusion of S0. S1a terminates at about 40C coolant temp. You can tell when S1a ends because the ICE begins providing the power needed to propel the car and charge the battery.

S1a is the worst stage because the ICE is on, burning lots of fuel to warm itself up, and the electric motor is powering the car and depleting the battery. One should drive slowly or sit and charge the battery during S1a for optimal fuel economy. This is why some users (rjent & others) reported better fuel economy on short trips using remote start to idle the FFH until S1a finished.

During S1a, the ignition timing is retarded & the ICE is producing almost no power. The focus is on heating up the catalytic converter as quickly as possible.

 

After my driving last night it appears that the car will go into S1a after S0 even when the coolant temp is above 40 C. Last night I got in the car after an errand and the coolant temp according to ET Mode was 57 C when I started the car. The car went into S1a after S0 and stayed in S1a until the coolant temp reached 65 C. Once the coolant temp reached 65 C it went right into S2.

 

Tip: You can skip S1a and go right to S1b by briefly shifting the car from D into L and then shifting back to D. You must wait until S1a starts to do this and you must keep the shifter in L until you hear the engine sound change indicating that the car has gone into Stage 1b. It is unknown what impact this might have on the life of the ICE or wear and tear on it. Ford has informed us that we will not cause permanent damage by doing this.

 

You can tell if the car is in S1a or S1b by the sound of the ICE when accelerating. In S1a the ICE will continue at idle and not rev while accelerating. However, it is a little harder to tell when stopped idling if you're in S1a or S1b just by the sound. The way to tell is to look at the Engage screen. The Engage screen shows total power demand placed on the ICE for both driving the car and power to recharge the HVB. When in S1a the power demand on the ICE at idle is less than .5 bars. When the car transitions to S1b the power demand will jump to typically about 1 bar while at idle. Since S0 & S1a typically deplete the battery, the ICE begins rapidly charging the battery once entering S1b.

 

Stage 1b (S1b): Continued warm-up with normal ignition timing and power.

Engine-off at stops: No.

Engine-off gliding: No.

EV Mode: No.

 

S1b is much better than S1a because the engine will power the car and the generator normally, but it still cannot engine-off glide. This stage immediately follows S0 if the coolant temperature is high enough.. Otherwise, S1b begins when S1a ends and lasts until the following points depending on engine coolant temperature at the start of S1b:

• below 40C/104F: until 40C/104F.
• between 40C/104F and 50C/122F: until 50C/122F. (I verified this last night)
• between 50C/122F and 60C/140F: until 65C/149F. (I verified this last night)
• I need to verify the numbers above in ET Mode but this appears to be what I have approximately experienced.

Post PCM update (13B07) it appears that S1b ends following the table below

• below 40C/104F: until 40C/104F.
• between 40C/104F and 45C/113F: until 45C/113F.
• between 45C/122F and 55C/140F: until 55C/131F.
• The coolant temp can also now drop as low as 51C/124F before making the ICE run for heat

Stage 2 (S2): Full Operation

Engine-off at stops: Yes.

Engine-off gliding: Yes.

EV Mode: Yes.

 

This stage starts when S1b ends. If the ICE temp falls below 50C you will go back into S1b. In the winter, the car spends a lot of time going back and forth between S2 and S1b in city driving.

Notes on HVAC usage

If you have the heat turned on, then the car will not move from S1b into S2 until the coolant temp reaches 60C. Heat use also makes the car much more likely to switch back into S1b after having been in S2.

 

Note: Engine-off at stops and Engine-off gliding will not work while the window defogger is on, even if in a stage where they otherwise would work.

Read about the Prius Warm Up Stages at: http://priuschat.com/threads/gen3-warming-up-stages.76501/#post-1068435

Edited October 27, 2015 by hybridbear
additional info from 8/20/13 in red text, 8/21 info in blue text, 12/3 info in green, reviewed 10/27/15

[hybridbear]

Since I began this thread right after getting the PCM update it appears the car was still learning. The behavior now is markedly different compared to behavior immediately after the update.

 

Now the ICE will shut off at much lower temps, as low as 40 C when stopped. It seems to consistently leave S1b and enter S2 at 55 C now instead of waiting until 65 C. You can tell when the car has reached S2 because on the Empower screen the blue threshold bar will appear for EV operation.

Edited September 30, 2013 by hybridbear
added info for post-PCM update data

[acdii]

One thing I noticed is after shutting down, and get going 10 minutes later, the ICE will turn on briefly, even though it is at Op temp. Only conclusion to this is the O2 and Cat temps are below proper operating temps, leaving the ICE in open loop. It will stay running until the cats and O2 reach operating temps then shut down. Pretty much S1b mentioned above.

 

Consider Open loop the same as choking a carburated engine. It runs rich until all parameters are met for proper combustion, once the O2 sensors are warmed up enough to determine cat function it will go into closed loop and try to maintain the closest to Stoich as possible. At this point the ICE will be at S2

[neod192]

Quick note : after the pcm update the ICE will stop at a light even if not at operating temp yet. It will start up again when you hit the gas and won't shut down when you let off the gas. It will only stop again if you stop or it reaches a certain time.

[corncobs]

Quick note : after the pcm update the ICE will stop at a light even if not at operating temp yet. It will start up again when you hit the gas and won't shut down when you let off the gas. It will only stop again if you stop or it reaches a certain time.

 

I always thought that was the plan for the PCM update but doesn't do that. It runs for quite a while once it kicked for the first time and it won't shut of until the temps are good.

[hybridbear]

Quick note : after the pcm update the ICE will stop at a light even if not at operating temp yet. It will start up again when you hit the gas and won't shut down when you let off the gas. It will only stop again if you stop or it reaches a certain time.

 

 

I always thought that was the plan for the PCM update but doesn't do that. It runs for quite a while once it kicked for the first time and it won't shut of until the temps are good.

I have found the same as corncobs. When first warming up the ICE still stays on even when stopped. However, S1b ends and the ICE will shut off at the thresholds listed above based on the temp when the ICE turned on last.

 

I'm updating post 1 with some additional observations from last night which are in red text.

Edited August 20, 2013 by hybridbear

[hybridbear]

Edits today posted in blue

[acdii]

 

I have found the same as corncobs. When first warming up the ICE still stays on even when stopped. However, S1b ends and the ICE will shut off at the thresholds listed above based on the temp when the ICE turned on last.

 

I'm updating post 1 with some additional observations from last night which are in red text.

Ditto. Same here.

[hybridbear]

I began watching this right after the PCM update. At that point my observations closely mirror what I had observed offhandedly before. However, just like how Ford is telling other owners with PCM update concerns to give it 30 days, now that a few weeks have passed I'm seeing changes in how the car behaves. It appears that after the PCM update the car goes into S2 at 50 C instead of waiting to get to around 60 C. The ICE still will not shut off below 40 C. Between 40 & 50 C it will only shut off at idle, but not while decelerating. Above 50 C the cars seems to enter S2 and shut off while decelerating. I'm working on some updated stages for after the PCM update. It appears that what I posted above only applies to cars that have not yet gotten the PCM update.

 

Since I still always skip S1a by using my trick above I don't have a lot of data on S1a. I don't really want to collect data on it either as I am convinced that my forcing the car into S1b is saving gas and I doubt it is having any negative effects on the ICE.

Edited September 3, 2013 by hybridbear

[hybridbear]

More information on Stage 1a:

 

Stage 1a is not very efficient as you'll notice that your instant MPGs are very low even though you're driving almost exclusively on battery. The reason why is that the ignition timing is retarded is to reduce emissions upon startup while the O₂ sensors are cold. For information about Ignition Timing you can read this explanation from How Stuff Works. In the FFH you can skip Stage 1a following the procedure outlined in the link above. During Stage 1a the ScanGauge II will show you that the IGN number is negative, indicating retarded ignition timing. The SGII will also show that the car stays in "Open Loop" during this time. When Stage 1a ends the car goes to "Clsd Loop". For more information about Open vs Closed Loop see this link.

 

The FFH allows us to skip Stage 1a and force the car to go to more normal advance ignition timing. Other hybrids, like the Prius, don't allow this. Based on what I've read about ignition timing and that the purpose is to improve emissions I don't believe that there is a detriment to the engine life for skipping S1a. And since the main reason for me to buy a hybrid has been for reduced emissions I justify my skipping Stage 1a as reducing overall emissions by reducing fuel consumption. Since during S1a the ICE is running at a low power output level and a low RPM it must run at that stage for a longer period of time before the ICE can shut off the first time. By skipping S1a I get my ICE to shut off faster and warm up faster which reduces emissions.

Edited November 14, 2013 by hybridbear

[lolder]

The Gen I FFH behaves similarly when cold shifting to L and then back to D. I worry that this is something you should not do as it is obviously not a normally planned operation. Remember that the name of this vehicle should be the "COMPROMISE GT". Peter doesn't like Paul very much.

[acdii]

If you are going from 0 to 55 though, skipping stage 1a by dropping to L and back should have no impact since you will be getting to 1B Very quickly anyways, especially if SOC is at or under 1/4. Thats my morning commute, or anytime I have to go anywhere from home.

 

http://www.youtube.com/watch?v=kzldLJcorbo

[hybridbear]

The Gen I FFH behaves similarly when cold shifting to L and then back to D. I worry that this is something you should not do as it is obviously not a normally planned operation. Remember that the name of this vehicle should be the "COMPROMISE GT". Peter doesn't like Paul very much.

Nothing I can find indicates that this operation serves any purpose other than reducing emissions by limiting the production of certain pollutants (oxides of nitrogen IIRC) until the O₂ sensors and catalytic converter components are warmed up. By skipping this step I pollute more for a few seconds but since I more quickly reach S1b where the ICE can shut off I pollute less in the long run by burning much less gas.

[lolder]

True. I've thought that also. There might be some part of the EPA test that requires it. The EPA tests measure emissions and not fuel consumed. Doesn't the new software warm up faster?

[Eddie Sessum]

I just wish the car would stay warm like a normal car. Its 80* outside and it cools to nothing in like 30-45min. Ive never seen something cool down so quick.

 

 

Maybe we will get lucky when it gets cold and that new pcm update will close up the grill when the car is off to help it stay warm.

[hybridbear]

True. I've thought that also. There might be some part of the EPA test that requires it. The EPA tests measure emissions and not fuel consumed. Doesn't the new software warm up faster?

The PCM update allows the car to enter Stage 2 at a lower temp. Pre-PCM update the coolant temp had to reach 60 C before the car would go into normal operation. Now it will happen at 50 C. It doesn't appear to have changed how quickly the car reaches a set temperature, it just allows it to go into normal operation at lower temps.

 

Stage 1a is also known as Open Loop. Don't ICE only cars also begin in Open Loop and not accept inputs from the O₂ sensors when cold? This would lend credence to your comment that the EPA requires this operating characteristic.

 

I just wish the car would stay warm like a normal car. Its 80* outside and it cools to nothing in like 30-45min. Ive never seen something cool down so quick.

 

 

Maybe we will get lucky when it gets cold and that new pcm update will close up the grill when the car is off to help it stay warm.

I agree. In a post elsewhere about grille covers I commented that the biggest benefit of the grille covers was slowing down the natural cooling of the ICE while the car is shut off. Since the grille shutters open when the car is turned off (even if it is cold) the car would cool down very quickly in the cold winter wind in Minnesota. In a few weeks we'll know if they do the same after the PCM update.

[Eddie Sessum]

A pot of boiling water doesnt seem to cool off as quick as this motor tho. I can go from hot to nothing on the gauge in 20minutes in 90* heat with no wind. Its strange.

[acdii]

Don't ICE only cars also begin in Open Loop and not accept inputs from the O₂ sensors when cold? This would lend credence to your comment that the EPA requires this operating characteristic.

 

 

Yes, they act the same way. Open loop replaces what used to be the choke system on a carburated ICE. It runs rich during this stage until the O2 and cats are up to temp, then switches into Closed loop, what I call Stoich mode. Thats when the readings from the sensors attempt to get the fuel mixture for the most complete F:A ratio of around 14.7:1.

[hybridbear]

Yes, they act the same way. Open loop replaces what used to be the choke system on a carburated ICE. It runs rich during this stage until the O2 and cats are up to temp, then switches into Closed loop, what I call Stoich mode. Thats when the readings from the sensors attempt to get the fuel mixture for the most complete F:A ratio of around 14.7:1.

So, is there any issue in forcing the car to skip Open Loop and go straight to Closed Loop using inputs from the O₂ sensors?

[acdii]

So, is there any issue in forcing the car to skip Open Loop and go straight to Closed Loop using inputs from the O₂ sensors?

Nope. I do it all the time, the ICE will remain in open loop until the sensors reach operating temp, but the switching from ICE just running, to ICE propelling/charging will decrease the time it takes to warm up as there is more load on it. The emissions will be much higher because of the increased load, but the warm up time being reduced may be a wash. When you consider if you start off with an HVB that is nearly depleted and have a cold ICE, its going to go into drive mode almost immediately, skipping 1a so it really doesn't matter at that point.

[FusionHybrid2013]

During S1a, I have been heavy footed on the gas pedal to get the empower guage up to a little past the third bar and that seems to engage the gas engine as the electric motor doesn't have enough juice to do it alone. I'll heavy foot it up to speed and then coast with my foot off the pedal. I usually have to give it two nice rounds of heavy foot/coast before getting to S1b. I'm not sure whether this is a good idea, but its what I've been doing and it leads to better mileage than not doing it.

[hybridbear]

During S1a, I have been heavy footed on the gas pedal to get the empower guage up to a little past the third bar and that seems to engage the gas engine as the electric motor doesn't have enough juice to do it alone. I'll heavy foot it up to speed and then coast with my foot off the pedal. I usually have to give it two nice rounds of heavy foot/coast before getting to S1b. I'm not sure whether this is a good idea, but its what I've been doing and it leads to better mileage than not doing it.

Pressing the pedal down and demanding more power than the electric motor can provide will force the car into S1b, but it also consumes a lot of electricity in the process. That's why I like the technique of shifting into L for a few seconds (until you hear the engine note change) and then back to D.

[Eddie Sessum]

Pressing the pedal down and demanding more power than the electric motor can provide will force the car into S1b, but it also consumes a lot of electricity in the process. That's why I like the technique of shifting into L for a few seconds (until you hear the engine note change) and then back to D.

Isnt that the design of the programing anyways? To drain the electric battery before starting to warm up the ICE? Draining it quicker or slower still is the same thing of wasting the charge.

[hybridbear]

Isnt that the design of the programing anyways? To drain the electric battery before starting to warm up the ICE? Draining it quicker or slower still is the same thing of wasting the charge.

When you shift into L and back to D the car skips S1a and goes to S1b which charges the battery while warming the ICE. This is much more efficient and saves gas.

[Eddie Sessum]

When you shift into L and back to D the car skips S1a and goes to S1b which charges the battery while warming the ICE. This is much more efficient and saves gas.

 

 

I know, im just saying in general its a crappy programing issue that causes us to have to do this. When the ICE is cold it should come on even if it just idles and doesnt power the car instead of waiting untill the batterys are almost dead and than starting it.

 

Wouldnt you agree?