Relooking at warm-up

gasper g above said if he dont leave it in ready mode it will do short warm up cycle......
soc not low in my case
if i stop for while.....sometimes[i should have said] engine will come on
anyway if its 50C ...it's probably the CAT REQUESTING a warm up

don't want to go off topic too much
lets see bob has anything new for us

 

About the topic of the relationship btw CAT temp and ENG temp, a couple of specific test showed me that both have to be taken in account. Pre-heating with a block heather does'nt seems to make skipping S1a but just S1b, cause a low CAT temp reading will start S1a anyway. In actual fact S1a seems to be made just for CAT warming up.

Cold Start at 18° ambient
T° eng = 18°
SOC = 53.7%
S1a unfolds @ 1500 rpm
Duration = 55/56 sec
Cat B1S1 at the end of S1a= 270°
T° eng. = 34° at the end of S1a
S1b following for 21 sec, ends @40°, when RWUP =0

The first black vertical line on the graph below represent the CAT getting to 228° at 30° ENG temp. At this temperature, in the next test, S1a ends and the engine shut down, not going in S1b.
The second black line represent the end of S1a.

"Hot" Start at 18° ambient
T° eng = 36°
SOC = 50.2%
S1a unfolds @ 1300 rpm (notice the different RPM relative to the 1500 of the cold start)
Duration = 52/53 sec
Cat B1S1 at the beg. = 39°
Cat B1S1 at the end = 231°
T° eng. = 48° at the end of S1a
NO S1b, engine shut down, ends when RWUP =0

The last condition in similar to an engine pre-heated with a block heater. Notice that S1a does'nt stops at 40° but 48°, because the 230° CAT temp was the figure the system was looking for.

COLD START @ 18° (S1 @ 0 km/h)


So the end of the story is that, to avoid S1a in all sort of conditions, you should fool both Eng. temp sensor and CAT sensor, with >40° and >230° . IMHO

 

confirmed my thoughts
great info thanks again

 

Forgot to add one important bit.

Every time that you go in ready, the reading of the CAT temp stay stable at the last reading in the ECU before the ICE was shutted down, that is always a huge value, tipically. The value of both B1S1 and B2S2, are actualized to the real (cold) value only AFTER the engine starts.

That means that the decision to start the engine on a cold start is made in the very beginning on the sole basis of the engine temp, beeing the CAT reading far off, on the hot side.

You can realize the consequences of that when you leave in EV with the CAT cold, even if the eng. temp is high: after a bit, upon power request, the engine starts and you find yourself suddenly in the middle of an S1a in motion. This exact feature makes a wise advice pushing a bit the accelerator before leaving just to double check that you don't need an S1a, and in case, making it standing still.

 

mmm...thats useful...

 

might consider exhaust heat wrap for CAT.....MIGHT just keep it a bit warmer

 

How do you measure the temp of CatB1S1?

That's my theory. By forcing the car to skip S1a you burn less fuel overall. My theory is that burning less fuel less efficiently will pollute less than burning more fuel more efficiently. I don't see how burning more fuel could pollute less. It also costs more. It may mean slightly more pollution per unit of fuel burned, but if you reduce your overall fuel consumption then you'd also reduce your overall pollution.

These numbers are purely for an example and their values aren't accurate. But lets say for example that each gram of gasoline burned once the Cats are warm produces 1/16th of a gram of NOx. Burning that same gram of fuel with cold Cats produces 1/12th of a gram of NOx. If the fuel consumed to reach the needed Cat temp requires 4 grams of fuel with the current S1a, S1b, etc process then you've produced 1/4th gram of NOx and depleted your battery. Perhaps by skipping S1a you could burn only 3.5 grams of fuel to get the Cats warmed up as needed. This would produce 3.5/12 or .29 grams of NOx.

But wait! You say...that's more pollution. But what you don't realize is that S1a depletes your HVB. To recharge your HVB back up to its SOC from before S1a began you would need to burn another 2 grams of gas producing another 1/8th gram of NOx. Now you've burned more fuel, 6 grams and have produced 3/8 (.375) grams of NOx. Since skipping S1a would mean that the ICE powers the car from the beginning your battery SOC would not be significantly changed during this time. Thus you would have burned on 3.5 grams of fuel and produced only .29 grams of NOx. If you compare the NOx produced per gram of fuel you'd see that skipping S1a pollutes more per gram of fuel. But since skipping S1a uses less fuel it produces less NOx overall.

I'm guessing that the EPA emissions requirements look at the grams of pollution per each gram of fuel burned, not factoring in how hybrids can turn of their ICE and save fuel and pollution.

The Prius cools off ridiculously fast!!! Even in warm weather stops of 10-15 minutes cause the ICE to kick on and not shut off right away (S4) because of a temp sensor somewhere requiring it.

 

I'm using a Log prepared with a lot of PIDs of interest using Torque PRO. Of course CatB1S1 is one of the pids, but i do record also B1S2.

So, for your calculation you would appreciate the fuel consumption evaluted with Torque, for the 3 separate cases. It would of course include the fuel to restore the SOC. It relates to the test i posted few msg ago.

The cold start (vehicle parked)

S1a @ 1500 rpm ; 55 sec ; 0.04981 LT ; .000956 lt/s
S1b @ 1300 rpm ; 21 sec ; 0.01799 LT ; .000857 lt/s

The "hot" S1a
S1a @ 1300 rpm ; 54 sec ; 0.040611 LT ; .000752 lt/s

Bear in mind, however, that in S1a, only little fuel is burned just for the sake of increasing the SOC. And compensate the engine ignition (made with the HV) and the electrical consumption of car's services. Just a quite small recharge and a SOC at the end of S1a equal to the SOC before ignition.
Even a sensor in the ECU exists that is called "SOC IGN ON"..... (Torque custom list ZVW30 can read it)

Very different story in S1b, where there's a substantial recharge of HV and increase in SOC, also if it's not a good bargain.. at the least you can do it in motion because ICE can drive the car....

Anyway, i share your position about burning less fuel (and then less pollution) skipping S1a. But it needs some objective support with numbers and figures.

My own impression is that S1a, forcing you to drive on the HV power if made in motion, put a limit (quite low) to the max pollution you can create during the first minute(s), moving ahead in time the pollution to restore the SOC used. But if the omologation tests lasts seconds or minute, like they do in EU, that could make some magic trick on your figures.....

 

This is the CAT temp reading in the Cold S1 , Bear :

 

Can these same data points be read with a ScanGauge? Very cool. There's so much to try to understand...

 

you can lock it with mechanical key .... little inconvenient but so it is if someone just drive it away

 

Nice graph! if only i have Torque set-up. (tried before but can't have SGII and Torque sharing the same data stream).

I still believe using the EBH long enough to have a "hotter" cold start at 50C does skip S1a and S1b. Your "hot" start example at 36C still falls within S1a and S1b coolant temp condition. One of the conditions that S1b transitions into S2 is when the coolant reaches 40C (104F) and above. There could also be a CAT temp condition, but I think is not a critical condition as coolant temp.

Today, my morning's start was at an ambient temp of 21C and coolant temp from a pre-heated block was at 55C.
The ICE didn't turn as I crept out of the driveway and into the street. It only started when when my foot demanded to accelerate at neighborhood speeds. During that time, my IGN was already instantly positive and also instantly drawing in amps at -16. Letting go of the accelerator turned off the ICE promptly and could glide all the way to the stoplight.

The rest of the trip uphill was normal.. S3 was reached when coolant hit 70C and through to S4 after the idle check.
If someone has Torque and an EBH installed, perhaps he can try replicating your experiment and graph the same variables but this time do a cold start at a "hotter" 50C.

 

Good observation there! So I think what's happening in my case is, cold starting at 48-50+ deg C (using EBH), the high coolant temp condition will override any tendency of the ICE to start at S1a or S1b because this condition (>48 deg C which is way above the 40 deg C S1b-to-S2 transition condition) is given priority than the actualized cold value of the CAT at the moment ICE is started due demand.

If it is cold started at around 36-47 deg C, even if EV'ed for a while, the ICE will still have to go through S1a or S1b once the EV is disengaged and the cold CAT demands a proper warm-up after the ICE is fired-up.. this is because after firing up the ICE, the coolant sensor also falls a few degrees momentarily as it catches the rest of the cold coolant in the system (and interpreted by the ECU to be a "cold engine") and probably is the reason why it takes into consideration the low CAT temp warm-up demand as well. Thus, it has to properly go through the motions of S1a and S1b operation.

This is just my theory as I've been using the EBH for 3 years all-year round.

 

I think most of Torque's PID can be hand programmed in SGII if not present, but the problem is that you identify certain behaviours only logging in a file the data, thing that SGII is unable to do. But if you want to just read the CAT sensor "bug" of showing the non-actualized high value when you put in ready, i think you can make it. I don't have SGII but i'm sure CAT B1S1 is available, you should ask in the SGII thread.

That's right, the very moment you ask ICE power, the CAT sensor is actualized and the miracle stops But beeing the coolant temp already high cause the block heater, you don't have to do S1b, which is something.
However, bear in mind, all that holds for Gen3, if you have Gen2 with slight different stages, the situation can be slightly different and you can have some other advantage, i dont know exactly.


If i was to make a hack to all the procedure, i would do it only on the CAT sensor, saving those unduly S1a with a warm engine and leaving the warming-up for low coolant temp, just to protect the engine and keep S1b.
Perhaps S1a will start anyway if the CAT sensor is fooled but not the temp sensor (and the temp is well below 40°), but it could be acceptable.

I cannot appreciate more the Ford Fusion B cerimony to skip S1a, that is brilliant and shows us that skipping it is not detrimental. Ok for S1b, but S1a sounds wrong... i tested myself if the B trick works on HSD, but to not avail... even tried to make the engine start in B rather then D or P, but only got a "bip"and a refusal....

 

Hmm, on a second tought, you could be right about skipping S1a with 55°C pre-heat..... but you don't draw -16A (unless you're braking) unless you're in a S1b, don't you? S1b tends to last a short time so ICE turning off could be just coincidental.
Always with the warning that you have a V2 Prius, so it could be different.

In actual fact i've got some sort of S1x with coolant temp of 70°, as mentioned before, so that's the reason why i think CAT temp is critical. That condition should equate to yours at 55°. Unfortunately i don't have a log of it to say which kind of S1x was, but it sounded as yours (yes, i'm convinced you were having a S1b ).

Thanks anyway, so the conditions, based on the evidence reported here, could be 3, with the last to double check with some figure:
1) S1a + S1b if eng temp is below 40° @ end of S1a - CAT temp not influential for a cold start
2) S1a only if eng temp is below 40° but gets >40° during S1a and CAT temp is below 230°
3) S1b only if eng temp is above 48-55° (or 40° ?) and CAT temp is below 230° (to be ascertained)

 

I've been watching this thread with some interest for awhile. All the tech talk about recorded OBD readings and such is probably interesting to those that love all the tech stuff and I'm not saying I don't, but how about some plain english for those that don't? What I would find most useful would be real world stuff like:
Before installing a EBH with the ambient temp. hitting in the xyz degree range, my average mpg averaged xyz mpg.
After using the EBH with the same ambient temp. hitting xyz degree range, my average mpg averaged xyz mpg.
Reading observed over the same route with approximately the same driving conditions in the same vehicle, etc.
Wouldn't that be an easier way for the non-tech savvy to see if adding an EBH would be beneficial enough to justify the expense?

 

well the thread is not dealing with EBH .......it's looking at the start up process and what's going on!
but if you hang around long enough the REAL WORLD application will emerge.....
either with a recommendation for a hack of the electrics or an adjustment in our driving style for the first few miles for max mpg.

all the graphs etc ...CAT temps at different stages etc etc...will help us pin point exactly what we have to do and when...as we drive to get better mpg

plenty of EBH info around prius chat...and other sites,,,,,just search

but hang around we're nearly there!

 

Hi Jeffrey, I think I can confidently say that adding an EBH (2-3 hours plugged in) effectively adds an average of 3.5 MPG for a 19-mile hilly commute (about a 500-foot elevation difference). That's my personal experience. so i guess a formula of 1 -1.5 mpg/hr of being plugged-in is a safe start. But there is a limit though as the thing is only 400watts and can only heat it to a max of around 58C based on what i've seen so far (that was during summer months).

compare that cost of 2mpg for that trip with the cost of electricity per hour and you can tell if using the EBH will be worth it for you.

I hope this answers your curiosity.

 

all quite on the western front!!??