10% MPG Loss After Fender Bender

[SacPrius2004]

Hi All, I've searched these forums and nobody seems to have experienced this:

My 2004 Prius was in a minor fender bender, front and rear damage. Car in shop for a month. Since I got it back, it runs differently. More reluctant to run in elec only mode. Takes longer to shut off at stops, or doesn't shut off at all. Battery indicator green more often. It's like the engine is not coming up to temp.

I took it back to the dealership and they said they hooked it up to diagnostics and drove it around and there is nothing wrong. But something is wrong. I've gone from about 46-48 MPG down to 40-44.

It's a long story, but I won't go back to the dealership where it was repaired. They're jerks. The guy at the body shop said they "had to purge the system". Could they have screwed that up and that's my problem? Could my thermostat be damaged from this pretty minor impact?

I need some ammo to take to the next dealership I try to solve this problem. Advice on what to check, possible causes, etc. I'm afraid I'm gonna spend 200 bucks to hear them say, nope, can't find anything wrong.

Thanks for help and btw the cabin heat seems perfectly normal, and I do understand MPG's go down in winter, but I've had this problem for 9 months now. It's definitley worse in winter but noticeable in summer too.

Walt

[Rokeby]

SacPrius2004,

To get started on possible diagnoses, the tech smart members will need
hard data such as:
* Mileage
* Better description of damages
* List of parts replaced
* Any diagnostic codes "thrown" by the CPUs
* Any previous damages
* Tire pressures
* Most recent tire alignment front/rear
* Throttle body/MAF sensor check/cleaning

They'll ask, but if you post it first, it'll shorten the turn-around.

Hopes this helps.

[dogfriend]

Hi, does the dealership that is populated with jerks start with a M?

I won't take my car(s) back to them either. I have heard that the dealership that starts with a R has a better service department.

[SacPrius2004]

Rokeby, thanks for the advice. I have kept track of my gas purchases and mileage, so I've got that; I believe they only replaced body parts, nothing in the engine, and no warning lights or messages appear when I'm driving.

Dogfriend, you got it! The place with the body shop at a separate location. I was bounced between the two several times, each denying responsibility. And a quote from a service manager there: "We don't know very much about these cars...maybe it's the gas you're using".

[Rokeby]

Originally Posted by SacPrius2004

... My 2004 Prius was in a minor fender bender, front and rear damage. Car
in shop for a month. Since I got it back, it runs differently. More reluctant
to run in elec only mode. Takes longer to shut off at stops, or doesn't shut
off at all. Battery indicator green more often. It's like the engine is not
coming up to temp.

OK, two really simple things to check for:
* are the tires at the air pressure you usually use? Dealers often take it
upon them selves to set tires at ~38 psi or lower.
* is the AC set to defrost? This simple thing really changes how the HSD
operates including denial of EV mode, and "excessive" ICE operation.
(Apparently its a safety issue; if you ask for windshield defrost, the CPUs
seem to be programmed to get the windshield cleared ASAP, runs the ICE to
get some excess heat "right NOW," FE be damned.)

Putting a lot of heat into the cabin means that the ICE has to run more often
and longer to maintain its own temps. There is/are also one or two electric
heaters that kick in depending on the defrost setting. These would add their
own electrical load, causing additional ICE run time.

I know if I wasn't able to drive my Prius for a month, I'd have forgotten all
the little tricks and twists. It would be like starting from scratch...
Newbiedom again!

Originally Posted by SacPrius2004

I took it back to the dealership and they said they hooked it up to
diagnostics [Emphasis added] and drove it around and there is nothing
wrong...

You should ask for a copy/printout of the 'diagnostics,' this would show what
if any codes were 'thrown' by the CPUs. They are really important in getting
to the bottom of difficult HSD/ICE operation issues. Get 'em, and post 'em if
at all possible.

Lastly, if there was damage at both ends, and there was any chance that
one or more of the wheels was impacted, I would suspect an alignment
issue -- seems like a competent tech would have already checked this.

[richard schumacher]

The "had to purge the system" comment is also worrisome. If they're talking about the inverter coolant and didn't do it right, it could be overheating. Get your car to a dealer who knows what they're doing.

[donee]

Hi All,

If the damage was to the left fender, the coolant heat recovery system could be damaged. It may not be functioning, and thus when the car turn off it does not pump coolant into the storage tank.

This could also be caused by poor purging (of air) of the coolant system, leaving lots of air in the system. Some kinds of pumps intended for liquids wont operate correctly if there is a large fraction of air in the liquid, or no liquid at all in the pump.

It could be a pinhole in a rubber tube, or a crack in a small casting, allowing air into the system as it cools down.

Have you had a colder year this year in Sacromento? Has it been blow freezing more often? The battery using a higher nominal SOC, is normal for below freezing operation of the Prius.

[dogfriend]

The dealership that starts with a M actually made my alignment worse when they tried to correct it. They also set all of the tire pressures to 32 during one visit. They overfilled the oil level when I took it in for the first oil change and they scraped the front bumper cover on my GF's Avalon on a service visit, but I did not discover the damage until after I had left the dealer and had no proof. So I don't go there anymore.

As suggested above, I would check tire pressure and alignment. I would also check the levels of the coolant in both reservoirs; the engine coolant at the front of the car and the inverter/transaxle coolant behind the inverter.

If you had a ScanGauge, I would suggest looking at the engine coolant temp right at startup after the car hasn't been driven for a few hours. If the coolant storage reservoir and pump are working, you should see a temp rise about 20° C above ambient temp when the hot coolant is pumped into the cylinder head.