Hybrid not active ?

I think you're lost: Prime Main Forum (2017-Current) | PriusChat

 

sounds normal. you will find all kinds of varyations when driving similar trips based on climate, initial battery level and etc.
the only way to track mpg's accurately is to measure every time you fill up and keep records.

how many miles on her?

 

Go to another Toyota dealer or find a Prius specialist in your area!!!

A dealership that refuses to hook-up Tech-stream unless a CEL is ON; doesn't know what they are doing and frankly wouldn't earn my business. There are many codes that take a while before they trip a CEL, and if the problem is intermittent - the CEL will probably never trip. I had an intermittent miss on my GMC; I could feel the miss whenever I'm in the mountains, engine under heavy load. The CEL didn't trip for 18 months. Once that ignition coil died, it was easy to find and replace it. A cheap OBDII reader was $75+ back then and parts store readers couldn't catch the issue.
There isn't enough information here to make an informed diagnostic; but according to your mpg - you don't plug-in and charge everyday?? Are you driving in snow; if those are snowbound or cold weather miles - that's normal. Does the traction battery charge and discharge normally as your driving? Faster than normal recharge and discharge is an indicator that there are bad cells going out in your pack. You can use the Dr. Prius app and Bluetooth dongle to do a quick check.

MAF sensor, dirty fuel injectors, marginal O2 sensor, cracked, loose vacuum lines, partially obstructed PCV pathway could be the issue. Or it could be something as simple as a bad tank of gas. Use high volume gas stations to avoid this; though this means that sometimes you'll have to wait your turn to fill up.

Find another shop or buy a knowledgeable friend some beer to start checking some of these things off the list.

Good Luck...

 

honestly, your car is fine

 

I've found that the PP is very sensitive to wind conditions. I've seen highway mileage (i.e. minimal EV use) vary from 50 to 70 mpg depending on whether I'm bucking a headwind or sailing along with a tailwind - both under similar temperature conditions.

I agree with BiomedO1 regarding the Bluetooth OBDII adapter. Get a good one and use the Hybrid Assistant program to monitor the car's operation during your trip. You can generate a report that goes on for pages and shows more info about the car's operation than any human can comprehend!

Ed

 

That is one BIG variable with the Prime. The other mentioned above is EV Auto. Put the two together and there is most likely no one here at Priuschat that can explain exactly or even closely what you're experiencing. Not many priuschat members (at least that I've read here) use EV Auto on a regular basis.
My suggestion is to put your Prime in HV mode during your commute and see how the car behaves as compared to EV Auto.

Again, there is that EV Auto mode. If you like it keep using it and learn how it behaves. And keep track of those days when you're driving a lot of extra miles. Because that will have an effect on how the Prime behaves as the computers try their best to make the car as efficient as possible given all the variations it's exposed to.

 

I never use EV Auto for all of the reasons mentioned above. I believe you will get a lot more consistent mileage by using EV mode at 40 MPH and lower. Driving at highway speeds the electric motor becomes much more inefficient and you'll be better off turning on hybrid mode.

Unfortunately, EV auto seems to follow it's own logic and never seems to do what you expect. I always assumed there was a random number generator determining when to use the battery and when to use the engine.

 

generally speaking, hybrid advantage is minimum on the highway. the battery spends most of it's time almost fully charged (hybrid portion, not wall charge)
uphill at highway speeds, it will use the battery for necessary power.

 

I just read the entire thread. So, just to be clear... You are using EV Auto all the time for your routine daily commuting, and getting once a week or so of the bad day barely get 40 mpg (not using any traction battery) and on the same trips on a "normal" day you get 48 to 50 mpg. Yet, you are saying you charge the car every day. Meaning the portion of your daily routine commute is done by EV from the traction battery.

So, how are you calculating the 40 mpg (not using any traction battery) and 48 to 50 mpg on normal days? On PP, there really isn't a way to calculate the HV only mgp. The only sure way to assess the HV only mpg on PP is to NOT Charge the traction battery and drive the car on HV only (using gas only) mode for at least a half tank (preferably full tank) and do the manual calculation (or use the car's 5-10% optimistic mpg display from a Tripmeter).

How many miles are you driving every day? What is your daily Eco dairy look like? On a bad day, does it show a lower EV ratio and very low EV efficiency along with lower mpg?

 

60 - 70 + mph in the winter is brutal on mpg. 40's is normal and the car usually doesn't use much if any electric on the highway in the cold. You'll see it use electric when you get off the highways at slower speeds.
At least that is what I see when I'm on the thruway, I-90 . Of course you can switch into EV mode anytime you want to use electric up until 84 mph. But you probably already knew that.

 

So, are your observations of 40mpg on a bad day and 50mpg on a normal day read from the display on the dash for each trip? If that is the case, the number fluctuation from day to day is perfectly normal. However, the overall mpg is unusually low IMHO. With my PP, going an average speed of ~65mph purely on HV mode on ~300 miles interstate hwy trips I frequently made in the past, I can usually get 55-65mpg depending on the trip. I think I might have had as high as 68mpg on the display. With a full tank method calculation, it is usually 5-10% lower than that number though.

Not charging a few days will not give you the accurate HV only mpg. You will have to start from a full tank and not charge at least you use half of the tank, preferably a full tank. On 150 to 300 miles trips ~25 miles of EV is going to have less of an effect on the overall mpg, but still depending on the way you use the EV mode, the final mpg will be different even if you have exactly the same HV mpg. It is still of interest to see what Eco Diary data shows on a bad day vs a normal day for the same distance driven. If the bad day consistently shows lower EV efficiency, then that is one explanation for the lower overall mpg on a bad day.

 

I had a six month assignment in eastern PA about a decade ago. Lots of rolling hills there. If your using your cruise control through those hills; that may be the source of your poor mileage. Every-time you go up one of those hills, your engine will over-rev; trying to hit the 70-72 mph set point; especially if your traction battery is low. Whenever I hit a hilly area; I kill cruise control and manually throttle it - speed up on the down hill and ease off on the up hill, to avoid the increase revs. That's kept my avg. mpg in the 60-65 mpg range. Even while traveling through the Sierras. Whenever I head up the mountain, I switch the car to HV mode - reserving most of the traction battery for the climb up the mountain. I try to keep my RPM's below 3K and accelerate on the down hill legs, so I don't have to rev too hard on the uphill legs. At the top of the Sierras, my avg. is usually around 38 mpg; by the time I get back home - I'm back to 60+ mpg and a half full traction battery. Mostly charging while going back down the Sierras, using cruise control to slow down decent speeds. Sometimes I see the ICE kick back on, to exert more braking force.

Your one bad day a week, pretty much rules out all mechanical issues, which leaves electronics and sensors. Unfortunately intermittent sensors and electronic components are very difficult to find and diagnose - unless you can capture a "data snap-shot" as the problem is occurring. As in my example of my GMC; I had to wait for the ignition coil to fully fail before I could find it and replace it. While I had an idea that was the root cause of my issue - I didn't want to blindly throw money at a problem that only occurs 1% of the time and wasn't going to leave me stranded on the side of the road. I could've limped home on five cylinders or simply drive 50 miles to an auto parts store to replace the component; if I was camping in the back woods.

Next time your car is in the dealership for service. Have the Technicians check all of your computer software revisions, make sure they are all up to date. OEMs send out software updates for minor system bugs they find after manufacturing. We only get notice of safety related updates that the NTSB would probably force the OEM to do, if they don't do it voluntarily. Also have the technician look for any pending codes, which would give you a clue to any issues you may or may not be having.

Hope this helps...