Is It Normal For Engine To Start Up First Thing?

[Birty]

Engine Always fires up on my 59 plate prius first thing when reversing out of garage after afew meters. Also revs high(choke like) and gives poor mpg for upto a mile or so?

Does same if left for several hours even if air temp is high outside..cant help thinking it aint necessary as Battery is charged and moving at low speeds. Not really asking much from engine first thing but always kicks in!

[korat102]

Mine always did that. You can use the EV button (if your car has one) to prevent the ICE starting under certain circumstances. It'll sometimes ignore your wishes though, if it's really cold or if the traction Battery is low for instance. I don't remember a higher than usual idle speed though.

[IanIanIanIan]

High revving first thing usually indicates that the traction Battery is low and it is taking a charge from the ICE, as well as it running to move the car, as well as running to warm up, as well as running to run the aircon. All a solid load so it needs the revs to produce enough power to supply.

Is the traction Battery in good condition?

[johalareewi]

When reversing, the Prius (and other Toyota hybrids) has to use the electric motor to drive the car. It is not possible for the ICE to drive the car backwards. If the HV Battery hasn't enough oomph to do the job (quite likely first thing), the ICE has to fire up and generate enough electricity for the electric motor to do its job.

Also, first thing in the morning, the Prius goes through the various start up stages.

[Grumpy Cabbie]

It will also fire up immediately if the a/c is on too high or the rear window heater is on and always if the front demister is switched on.

And to reiterate (in a nice way), the Prius is a hybrid. It is not an electric car. It is a petrol car with some limited electric assistance.

[Birty]

Just passed hybrid health check so assume all good? Just surprised it seems to be on choke first thing every time with no load conditions... Getting 55 mpg on a 6 mile rural run with 2 mile in town at the end of journey...

[Grumpy Cabbie]

Does this 'running on choke' happen all the time or just when you first start the car up?

If it's just cold starts then it's normal, but if the engine runs all the time when first started up such as popping in for a paper and then starting the car again then I'd be concerned. Good to hear that the HHC is clear but is the vent to the rear HV Battery clear? Is there a coat or a bag or seat belt blocking it? Do you have a pet on the rear seat? Do you keep the a/c on recirc all the time? Is your climate system on front windscreen? What's the condition of your 12v?

[Birty]

None of the above .. All good, nothing left on when i turn off.. Revs high only at first for short while.. Not aware of any 12 v issues.. Nothing to,cause concern. Very health car . Think this is normal but just wondered why is the choke kicking in so often on start in a heat wave? As stated it dont last long but still surprised.... Just seems to be a good way of burning fuel...

[timberwolf]

I believe the warm up is required for the emission control system (i.e. mainly the catalytic converters). You may think it is hot, but unless your car engine is above about 40C it thinks it is cold :)

Please do a search for The Five Stages of Prius Hybrid Operation document on that there internet.

[PeteB]

...just wondered why is the choke kicking in so often on start in a heat wave? As stated it dont last long but still surprised.... Just seems to be a good way of burning fuel...

the Prius doesn't have a choke, although the fuel injection system does adjust the amount of fuel injected to allow for the coldness or otherwise of the engine.

During warm up, unless you're demanding a lot of power, the engine timing is heavily advanced (or is it retarded - can never remember!) and makes a negligible contribution to driving the car (but it may gently charge the HV Battery if you're not moving). During this time most of the motive power comes from the electric side. This mode makes the engine inefficient in producing torque, but very good at making heat. It's as if the engine is divorced from the Hybrid system for a few minutes, and is one of the many things about the Toyota/Lexus Hybrids that still fascinates me after over 12 years and nearly 300,000 miles.

If you stamp on the pedal it snaps out of it and gives plenty of motive power.

[Birty]

Great answers all... Need to read the five stages info...mr T.Wolf.... Im sure all is correct but hate to hear the engine reving! Maybe in the middle of winter to heat the car (and me)up but to hear it during a heat wave still sounds odd!!

[Grumpy Cabbie]

My engine barely runs in summer and certainly switches off after the first 1/4 mile. Even if I pop to the shops a mile or so away and return home, leave the car for an hour or so and then head out in it again the engine is still warm from before and doesn't switch on unless demanded for acceleration etc.

If your car is running the engine at start up when warm and you have the heating system switched off and the Battery vent isn't blocked, then I'd start to become concerned. What level does your HV Battery generally sit at? Is it 6/8 7/8 or mostly 5/8 bars?

I've had my engine run similar to how I think you're describing yours and that was when my HV Battery ecu had failed. The car was struggling to balance the HV battery and ran the engine more. The HV battery would sit at 5/8 bars and the car was reluctant to use it.

The other time my engine ran all the time was when a customer had blocked the HV battery vent on a hot day in town after a busy day. Once they'd got out the battery cooled down and the car went back to normal operation.

Another time my car ran the engine almost continuously was just prior to the EGR valve failing at 75k miles!

Finally. You haven't answered your use of a/c. You mentioned the engine running in a heat wave. Do you leave your a/c on manual in RECIRC and/or the temp set at LOW? If so, the chances are that the HV battery isn't getting the air flow over it it would need to cool itself and thus gets warmer than it wants. This then causes the car to err more on using the engine to protect the battery from over heating. If you also have the a/c set at LOW and run the fan hard the a/c gets it's power from the HV battery causing it to get warm.

[Birty]

Ta GC.. Aircon.. Don't really use it that much...like i said no load on engine first thing... No blocked vents, usually only me in it....convinced all is working as should Battery up at top and gets used etc etc... All 5 stages as should be but stage one seems to be more than i would expect.. Although after a 10 min drive, a 45 min break and then restart the engine did not kick in last night for most of journey back....was warm here last night though.. On a 19 mile commute i get 60 plus mpg but on my short 6 mile commute just getting 53 ish... The answer is work further from home and use a block heater first thing..lol....will monitor engine use more now you confirmed you have had issues... New egr ( thought only diesels had them nasty things!) and ecu... Expensive no doubt...

[Grumpy Cabbie]

Check your radiator level otherwise all seems fine.

Yeah a lot of new(er) petrol cars have egr valves. Mrs Cabbies IQ has one and it had to be replaced under recall at massive cost to Toyota. Mine was about £400 as it was out of warranty (I own an early gen3 and thus only 60k mile warranty), but it ran lumpy, then continuously before getting worse. Would appear to be cheap Asda fuel as they were the only cheap station around :) Now it gets a diet of Shell V Power purely because it's cleaner stuff. The HV Battery ECU was a warranty item and I think I've had two of those or at least big problems with it which then needed the part replacing. It was about a grand if I recall but under warranty.

I'm on my third steering motor though but don't worry as the t-spirit has a stronger version less prone to failure. They were replaced under warranty but are about £1,500+vat+fitting if I recall!

Mine was one of the very first gen3's - and it shows :( But many are proving hardy with many examples on Autotrader well over 150k miles.

Don;t worry about the 5 stages. They're for information only and the car almost has a mind of it's own. Generally unless there's a warning light or message the car is running fine.

[Birty]

Thanks again GC. Just done a proper test run and 75mpg over a 23 mile trip! Engine cut out about 0.5 mile into trip... Convinced all is ok and now aware that the initial fire up is to warm things up, not just to burn fuel!! Good to see you use good fuel.. Me too but dont always stretch to vpower! Just off to hunt down an extended warranty..Lol !!!

[MEP's Yaris GS]

Great answers all... Need to read the five stages info...mr T.Wolf.... Im sure all is correct but hate to hear the engine reving! Maybe in the middle of winter to heat the car (and me)up but to hear it during a heat wave still sounds odd!!

It's not the much of a heat wave at the moment (or at least it isn't on the coast lol) but you've got to remember a warm engine is normally in excess of 85C for most engines, air temp is only 25C currently, so always a cold engine when it's been sitting. The only advantage of this time of year is it should warm up faster.