Need help diagnosing strange MDF display along with possible lost of electric power

Short version of the story is that '05 Prius with about 92,000 miles and has 6yr/100,000k extended warranty. Recently sudden 7-10 MPG drop without change in driving habit/behaviors. MDF energy monitor at time showing electric motor is putting out electric power and charging the battery at the same time. Lost in power resulting in ICE almost always on. Dealer's service department thinks there is nothing wrong with the car. I really need to figure this out before extended warranty expires.

Could it be that there is something wrong with the electric motor or hybrid battery, resulting in the lost of electric assist, and causing the ICE to always start?


Now the LONG version of the story.

I live in Los Angeles and have a '05 Prius with about 92,000 miles on it. There were service events leading up to this point and I'm not sure if its relevant or not so thought I'd list it out anyways.

On 8/2 (Sunday), I brought my '05 Prius to the dealership for scheduled 5K miles service. I'm sure not everyone would agree with this, but I do my service at the dealership hoping to increase/retain the resell value.

At any rate, upon dropping off the car, the service personnel suggested the throttle plate cleaning. Considering I was getting close to 100k, I went ahead and agreed to it. After the service was done and I was on my way home, I noticed the ICE revving even when I was at full stop at the traffic light. When I got home, the ICE was still revving itself after I've pulled into my drive way and after I've put the car in park. Since I picked up the car after their service department had closed, I couldn't just bring it back and have them check on it immediately.

On the following day (Monday), I called the dealer and was told to bring it back for checking. I made an effort to leave work early and brought it back on Tuesday. After waiting for about 1-2 hours, they told me their service tech didn't properly clean the throttle plate the first time, but they've done it now.

Got on my way thinking everything is now fixed. However, I've started to notice an increase usage of ICE compared to before the initial 8/2 service. Almost to the point that I can't touch the gas peddle without the ICE turning on. At first, I thought the dealer didn't set the tire pressure correctly after rotation and didn't think too much of it. However, after dragging my feet and eventually checking the tire pressure on 8/15 and discovered it was not the problem. I emailed the dealer service manager on 8/17 and got no response so I called on 8/24 and was told to bring it back in for checking. Brought it back on 8/25 and left the car there for 1 day and 2 nights. On 8/27, the dealer called back and swears they can't find anything wrong with it.

I picked up my car on 8/27 and on the way home, I started noticing something I've never seen prior to the 8/2 service on the MDF. The MDF energy monitor at time shows the orange arrows to the wheel, indicating electric motor is putting out power, but also green arrows to the battery, indicating its charging at the same time. The problem of ICE always turning on still exist. At times the hybrid battery don't seem to want to charge. I've attached a picture for review.

Thanks for reading the LONG story. Please help because I really need to figure out what's wrong before my extended warranty expires, since the dealer appears to either not notice or don't want to acknowledge the problem.


Thank you!!

 

Donee: in my past experience with my '05, during low acceleration, usually it has the ICE flowing to the tires and and electric motor, while battery flowing to the electric motor, which then flows to the tire as well. I don't recall ever seeing this type of display before. Besides, I don't recall ever seeing the ICE trying to charge the battery during low speed acceleration from full stop, when the car needs power the most, especially when the battery is not in the pink. I will try to take a video of the display tomorrow and post.

efusco: the SOC seems to be stuck between 4-6 bars I have not seen green or pink for a while. Normal commute for me is about 75 miles a day, 90% freeway. But being in Los Angeles, some stop and go traffic are involved, which normally adds to the MPG due to more gliding. I have Michelin tires with max psi of 44, set at 43 front and 41 rear. I also have standing order with the dealer to only put in 3.5 quarts of oil because they used to overfill the first couple of time and after I got fed up and made them take some out, they setup in their computer system so it prints a x____ for the foreman to check and sign before returning the car to me. However, I will double check tomorrow morning then report back. as for what other things they did, it was a standard 5K service + cabin air filter + throttle body chamber cleaning. the only thing i've never had done before is the throttle cleaning. on the service sheet, it states "added fuel additive to fuel tank" but considering I'm on my 3rd tank of gas after the service, there are probably non left in the bladder anymore.

TonyPSchaefer: Thanks for the welcome. =) To be honest with you, I've lurked for a long while and learned A LOT from these forums. I actually don't mind taking it to another dealer as there is one closer to my house than the one I normally go to. But I don't know how to describe my current problem other than lost of MPG. This is part of the reason I really need everyone's help to diagnose this so the dealership can take me more seriously.

Richard Schumacher: during the 92,000 miles, I've seen the ICE charging the battery and driving the wheel, but I don't recall seeing the electric motor charging the battery and driving the wheel at the same time. I may be wrong, but my understanding is that the battery is the source of power for the electric motor and therefore is yellow arrows flowing from the battery to the electric motor, then to the wheel, or green arrows flowing from the wheel to the electric motor, to the battery during regin. As previously mentioned, there are many times when the ICE is driving the wheel (red arrow to the wheel) and charging the battery (red arrow from ICE to the electric motor and green arrow from electric motor to the battery).

During my evening commute today, I've even noticed times when it showed ICE to wheel and ICE to electric motor (red arrows), electric motor to wheel (yellow arrow), but no arrows to or from the battery. If my understanding is correct that electric motor is driven by the battery and not the ICE, the yellow arrows should not have been flowing if there are nothing from the battery.

As for the damaged mass airflow sensor, how can I tell and what should I say when I bring it to another dealer?

hobbit: thank you, I will call them to find out about if they've dismounted the throttle body but please let me know what is a "TPS". Thanks!!

Thanks to everyone for the reply. Please help let me know if anything else you can think of before I bring it to another dealer. Thanks!

 

efusco: forgot to add that i've put on about 1000 miles since my initial 8/2 service. as for determining fuel economy, i keep a modified john1701a excel file and have logged every tank since i purchased my '05 with 6 miles on the ODO. during these past few days, temp is about 105-110'F in los angeles and i'm showing 45 MPG for current tank on the display, after putting up significant effort to glide (without much result) and following semis. prior to the 8/2 service, the MPG would easily be in the 53-58 MPG during this type of weather when i put up effort to conserve fuel.

 

i did some youtubing this morning and found several clips of energy monitor for '06 and later models showing arrow behaviors as i've described so i may be wrong on thinking this is a part of the problem. however, honestly don't remember seeing this type of behaviors before. i'll change the topic of the thread.

regardless, my main concern is not about the MFD, but about the suddent lowering of MPG and possible additional wear on the ICE.

I've check the oil level and found it within the two dots. called the dealer and am waiting for someone to call be back regarding if the throttle body was dismounted during cleaning.

Mike: regarding the 12v, checked this morning after car has been sitting in the driveway for about 12-14 hours indicates 9.6v. will now go drive around for 30 minutes to ensure full charge before checking again and report back.

thanks everyone!

 

sorry, quick search in faq didn't find instructions on how to change the title of the thread... will try looking for it again after checking out the v12 battery charge.

 

Rokeby: thanks for the reply! I checked the 12v battery status using instructions found here --> http://priuschat.com/forums/gen-ii-prius-technical-discussion/39798-12v-battery-status.html

I took the car out for a spin. My house is about 0.4 miles from the freeway entrance, drove 15 minutes at around 63 MPH, got off the free way, then drove back home going the other direction on the same freeway. Outside temperature is about 108’F, A/C set at 68’F with “LO” fan. The trip total distance was 35 miles.


Time HV battery SOC
1:05pm 5 bars
1:08pm 4 bars – got on freeway
1:10pm 5 bars
1:14pm 6 bars
1:23pm 7 bars – during freeway exit, breaking appears to have increased regin
1:24pm 7 bars – got on freeway going other direction
1:28pm 6 bars
1:36pm 6 bars – started following semi and slight down hill
1:39pm 7 bars
1:41pm 7 bars – exit freeway
1:43pm 6 bars – arrived home

It took nearly 15 minutes of freeway driving to charge the HV battery from 4 to 7 bars on the way out. Also during the drive, I’ve noticed that car started behaving normally after the HV battery reached 7 bars (green) at 1:23pm. On the way back, noticed loss of power at 1:28 after SOC went down to 6 bars. At 1:41, after exit of freeway with 7 bars, was able to glide the whole 0.4 mile back to my house, even after coming to a complete stop at the freeway exit traffic light.

Parked in the drive way, and checked 12v status after shutting down. 12v battery showed 12.2. Turned on the head light dropped it down to 9.0v, turning off the head light and saw it raised back up to 10.2.

After seeing what Rokeby wrote, it sounds like the 12v battery. Called both dealership for price quote. The original dealership which did the 8/2 service asked for $174.76 on parts + $85 labor. The other dealership’s service department was closed for the weekend.

Here comes the next question. Should I get this fixed at the dealership immediately? Or should I order the Optima unit from eLearnAid and wait for it to arrive before swapping it out? Considering I will be going on an 8 days business trip on 9/2 so the car will probably just sit in the drive way during the trip. I have Nav and smart key.

Also, I’ve read through hobbit’s very impressive battery guide and have one question regarding floating the ancillary 12v battery. Can I just hook the jump point up with another car using jumper cables to avoid loosing settings?

Thanks!!

 

Vertex: thanks for the suggestion on the Exide model. In the end I decided to go with the Optima consider it was cheaper than what the dealership wanted to charge me for the OEM, before labor charges.

Donee: thanks for your reply, its all good. After your message I did some youtubing and discovered it seems very common for '06/after models. Perhaps it is also common for '05/before models but I honestly don't recall seeing it before. However, it probably isn't part of the problem so I'm now not very concerned about the display anymore. Besides, I'm not the type who throw out a question, then expect "hand holding" from there on, so I totally expected to put up effort on my end when asking for help. =)

At any rate, a BIG thank you for everyone who have put in suggestions. I've ordered the Optima + kit for total of $163-$25 MIR, w/free shipping. Will work in this direction and report back regardless if it solves the problem or not.

One last thing, I'm still interested to learn about floating the ancillary 12v battery, thanks!!

-don

 

I came back from my biz trip on Thursday and somewhat to my surprise, car started fine. Replaced the 12v battery today, which was relatively easy. No corrosion on the terminals of old battery. But unfortunately it doesn't appear to have solved the problem.

Something I want to add to how I feel when driving, and things I've notice is different compare to pre-service. It feels like the ICE is almost always trying to charge the HV battery and therefore I'm not getting any power assist from the electric side. Car starts to feel normal once the SOC gets to 7 bars (green) and I can glide without much effort. On the few occasions it got into the greens, it took a long down hill or downhill freeway exit to get there. On most drives it never gets to 7 bars but instead stays at 6 bars for the whole 20-40 minute drive, rarely going below 6 bars and never getting to 7 bars.

It now doesn't feel like the TPS. Would MAS have this type of effect? Or is it the HV battery? I'm really hoping IF it’s the HV battery, I have it figured out before the extended warranty expires. Please help suggest what I should do next. Thanks!!