Running out of ideas

New here and must say that Pchat has offered lots of info and has good contributors. Have a 2008 Prius non-touring, bought new, almost 3 years of ownership, and it has been great until the past 6 months or so. Used to get 42-43 MPG carpooling (2 people) all the time then 6 months ago, 35-36 MPG. Adjusted tire pressure 41-42 cold front, 40 cold rear, helped a little bit. Checked the 12 volt bat and replaced, back to 38-39 MPG. BUT no better. Even though no warning light, took to dealer to have hybrid bat checked out, fine. Car has almost 60K miles so could it be down to:

1) Worn out shocks? Have Blitz springs and the ride has been rough lately but did the push the bumper test and it didn't float? Tires and wheels combo weight about the same as stock, give or take 1-2 lbs each. Have had this set up since day two and when was getting 42-43 MPG.

2) Dirty air filter? Was replaced at 30K so will replace shortly.

Could those two really cause that much drop in MPG? Anything other ideas? Fuel injectors? "Winter" gas?

TIA

 

- Have you read This Thead Yet? Yes, btw, s/b corrected to "Thread".

- What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations) Both trip computer and manual calculation (miles driven/gallon refilled).

- What fuel economy are you expecting and why? 42-43 MPG, because used to even thru the previous So Cal winters.

- What are the approximate outside air temps? 60s-70s recently.

- How long are your trips? Mixed, but no improvements even on long trips of 40+ miles one way.

- How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving? Mixed again, speed limit on streets, slightly above on hwy.

- What region/state are you in? (if you haven't set your location in your profile) Southern California, not too cold.

- What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.) Flat and gentle hills.

- Is your oil overfilled? (i.e. above the full mark on the dipstick) No.

- How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here) Just replaced by Toyota, 1 month old.

Have you had your alignment checked? Any pulling or abnormal tire wear? Normal, no pulling.

- Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15). 215/45/17 Sumitomo with RPF 1 total 1-2 lbs more than stock.

- What are your tire pressures? , running 41-42 psi front, 40 rear.

- Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.) V8 so not a good comparison.

- How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking? Almost grandma but still no improvements.

- Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on? Here and there.

- Are you driving using D or B mode? "D"

- HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to? Tried them all, on off, auto, etc., no differences, really.

- If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute? No.

 

I've given up on that, too slow for me and most cars behind, so back to how I used to drive when I was getting 42-43 MPG.

Thanks for your response.

 

Yeah, going thru the process of elimination and read about that. Will clean the MAF sensor when replacing the air filter soon. Alignment probably will be last since the car tracks pretty straight. Luckily the streets in Orange County is nicer than LA.

 

The engine does seem to be "on" more often than before and no massive stereo system. Had a bad 12v bat and know all of the symptoms and this new one is not exhibiting any but will do the check thing again thru the touch screen and post the voltage.

 

No, don't "warm up" the car, 5 second then backup.

No, after buying this car the MPG on the screen became like a game so always pay attention since mid 2008 and now it's this low and when it was even lower 35-36 w/bad 12v bat, it has been driving me crazy.

Yes, will check on the MAF sensor as I continue the process of elimination.

 

No, was just saying that there are less potholes in OC than LA. Driving style is the same but was trying extra light footed which didn't work so back to how I drive when I got 42-43. No changes here.

At this point, it looks like these are the next on my process of elimination:

1) recheck the new 12v bat
2) change air filter
3) clean MAF sensor
4) alignment
5) new shocks
6) EV mode mod?

Then maybe on to gen III if still doesn't work as had one for a couple of weeks and 46+ MPG was no problem even with more agressive driving.

 

1) recheck the new 12v bat - ruled out: VSCM mode 12.5V; 12.1-12.2V loaded; 14.2V charging

 

Yes, will keep rechecking. The original bat that was just replaced was in the 9-10V range.

Never mind the OC vs. LA, just OC. Street driving is now 3.3 miles less but less up and down medium grade hill. Hwy driving is now 6 miles less, similar speed.

Never used the heater. Have always used auto even when was getting better MPG and have tried not using AC/auto for months, no difference for me (my own experience).

If these cars are this sensitive to changes, may just might go back to gas guzzler.

Thanks for your inputs will try the air filters, MAF cleaning, etc. and report back.

 

Before 23 miles 35 mins, current 13 miles 20 mins. Note that with the longer commute, towards the end I was also getting the lower MPG (38-39, before the 12V bat went crazy then 35-36) vs. before 42-43 on same commute so the problem started before the commute changed.

I've tried not using auto or A/C (except when super hot) for months recently and no change. Per my own experience, I used it all the time and was still getting 42-43 MPG. I got back to using it recently and it didn't bring the current bad MPG of 38-39 down any further.

Just think that a proper hybrid should easily get in the 40s without much effort if the recent/upcoming small cars can get high 30s without being a hybrid.

Toyota dealer replaced the battery and if memory serves me right, I had to reset all the radio stations so I believe it was fully disconnected.

As for the tires, last set lasted almost 40K miles and had about 100 points lower wear rating.

 

The 17" wheels have been on the car since day two so I was satisfy with 42-43 MPG as I was expecting it and it was like that for 2.5 years.

1st set of tires = Kumho Ecsta AST, lasted almost 40K miles
Current set of tires = Sumitomo HTR Z, almost 20K miles so far

Current tires were getting 42-43 until about 6 months ago.

The chase continues...