Interpeting OBD "Help"

Do you know much about the condition of the hybrid battery?

I think I'm seeing pretty normal numbers as far as the data given- the gas engine seems to be running fine.

That makes me wonder if the hybrid battery is getting weak, and is therefore less available to help out when you push the skinny pedal. The computer normally solves this problem in real time by forcing the gas engine to shoulder more of the load, which means reduced MPG.

Although sometimes hybrid batteries last longer, 16+ years in a hot climate is a pretty good run.

 

^^^ +1

Additional questions.
1. How many miles on the car?
2. Do you know the past history of the hybrid battery?
3. What gas mileage are you getting?
4. What type of driving? City, highway, mixed?

In all likely hood, the hybrid battery is weak.

 

Are you in Arizona? AC usage will reduce gas mileage.

It looks like the ICE is working fine. Wait until you have four full tanks of fuel, them calculate the fuel mileage.

 

Just use what you're taking out and putting in these cars should almost go 400 420 mi until you're flashing light is on. Then you have about 30 mi to find gas or be sitting there looking right silly and then at that time you should be putting in about 10 gallons of fuel 10.1 10.3 I got an '09 telling me I'm getting 37.9 mi to the gallon but by the filling up and figuring out what I've taken out and all that I'm getting 40 something oh well that's about right to the above scenario driving works out and all of my generation twos which are three right now I think and it works out to be about the same some of them at different mileages or a different places on the gauges for whatever reason that doesn't matter I know I have one or two that take 300 miles to get to a half a tank and then from half a tank to a quarter is almost seemingly instantaneous and so on but at by the time the flashing pip is flashing we're sitting at 400 mi 420 somewhere in there like clockwork and all of them that I've had so far.

 

Sounds like it's safe to rule out a tired battery- a new Toyota unit is as good as it gets.

A/C certainly causes more fuel to be burnt, but if you've been living in Arizona for a while I'll guess you used A/C the whole time.

A measurement error as Tombuk2 suggests could do it- worth comparing the dash display to a real calculation.

 

When the engineers test the powertrain, they figure out what is needed (fuel, ignition advance, etc) to achieve their goals (hp, emissions, mpg). Those values are programmed into the ECM.

As the engine runs, the ECM looks at several sensors (RPM, Mass Airflow, temperature, etc) to determine base fuel injector on time for that particular moment. After combustion, the Air Fuel Ratio sensor (located in the exhaust manifold) produces a signal that indicates the resulting AFR.

If the engine achieved the target AFR (fuel mixture), then nothing is changed for the next injection cycle. If the AFR was "lean", then Fuel Trim makes a positive correction to add fuel. If "rich", then a negative correction to reduce fuel.

So the "%" is a percentage of the current injector base on time. "Zero percent" is basically no correction, as it left the factory, and "everything's perfect".

Short Term Fuel Trim is a reaction to the AF sensor. If STFT moves "too far" away from zero, Long Term FT steps in. LTFT is a learned correction that's stored in memory for a given range of "RPM x load " values. STFT plus LTFT gives you the total correction value.

0 +/- 5% is "perfect". Up to 10% is fine. 15% means something's not right. Above 20% will set codes.

Catalytic converter temperature could be an algorithm that's based on operating conditions. Or it's inferred by monitoring the amperage of the A/F and O2 sensor heaters. As the sensor temperature goes up, heater resistance increases, so electrical current goes down.

That said, I have never paid much attention to converter temperatures. Fuel trims and (a lack of) engine misfires are more important for converter health.

MPG has a bunch of things that can affect it. Tire type (low rolling resistance )& inflation, exhaust restrictions, HV battery condition, missing areo body panels, 12V battery condition, general engine "health" (compression, cam timing), etc.

Posted via the PriusChat mobile app.

 

"It depends".

Fuel trims are additive. (+10%) ST + (-5%) LT = +5% total.

STFT will move around a bunch as you drive. It can vary a percent or two at steady state conditions, but that can be on either side of 0. It can do weird things on decel. Or not. Depends on what the engineers decided to do.

LTFT is a better indicator of trends over time. If something doesn't happen long enough to affect LT then I won't pay too much attention to it - most of the time.

If I have a problem, then I look at STFT.

Posted via the PriusChat mobile app.

 

Well, Chapman keeps pointing to the "2004 Toyota Prius new car features". It's a lengthy publication that covers much of the theory and operation of the Gen2 Prius. Apparently the only source is to get a short term subscription to Toyota TIS and download it from there.

Posted via the PriusChat mobile app.

 

Our wiki page Toyota Service Information and Where To Find It | PriusChat does a good job explaining all that.

Yes, the New Car Features manual is the "missing volume zero" of the repair manual, the one that explains the whys and hows of all of the whats the later volumes talk about.

But at TIS you find more than just that. There's a whole separate tab of Quick Technical Guides on all sorts of topics, and up at the top is a Technical Library tab that gets you into all of the "University of Toyota" course materials used in training their technicians.

The wiki page tells you about all of that.

 

Thank goodness when the dream was conceived back in 1994 and shown at Tokyo. Most of the engineers and designers were still for the most part Toyota people. There was a lot of input from other sources including companies in America but still it seems that 2010 is when all the hubbubs started and was executed very well specifically for the western markets it seems like and things took a turn for what this person says is for the worse. When things kind of went a little bit south for the Prius of course they had become popular and people in the know I guess came to expect certain things like they did from Corolla and other Toyota vehicles and apparently they were seeing a trend trending kind of downward and away from that certainly what I saw with the generation 3 but with the two and the original which is pretty much the same as the two they had something and then they didn't That's just my take on it. That's why people that seemingly are in the know of the car business kind of stick with the generation too and will work on the others because of their money makers if you will. The generation 2 I guess is not because it's really like a regular car for the most part the one and z engine and all of that other than the CVT with the electric motors and some cabling and a battery everything was pretty much as normal Toyota. Which is a keeper.