VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG

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Thu 12 Dec 2019 21:20
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Ryan71

Hi Guys,

So I jump started my friends ford Fiesta Zetec as his battery completely died, and before doing so my VW Golf was giving me around 75 - 80 MPG on the motorway, even in cold.

Straight away after using my car to jumpstart his, I think it has had an adverse affect on my cars battery/alternator/fuel injectors?

My car now very slowly the MPG goes up and the maximum I can get out of it driving eco friendly is around 65 MPG, also when starting the car it sometimes takes a little longer on the Ignition, and when idling the MPG starts to drop, this was not the case before.

has my battery been damaged in jumpstarting his? and what can I do to fix this?

thanks in advance

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Thu 12 Dec 2019 21:47
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - gordonbennet

Its maybe had an effect on the dash display (could be worse, jumping a friends car cost my mate £hundreds because it blew his whole Laguna digital dashboard), but have you compared brim to brim fuel figures which is the only reliable fuel figure.

Have you also compared your car with REAL MPG figures, above.

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Thu 12 Dec 2019 22:22
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Ryan71

Thank you so much for your reply,

Ahh i see it could have been alot worse, In terms of performance I mean it does seem like Ive lost efficiency by looking at my fuel gauge, will this be rectified once my battery recharges itself?
also whats the best way to do this, isit just to drive around with min electronics or to plug it in?

Thanks

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Thu 12 Dec 2019 22:38
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - gordonbennet

Looking at your fuel gauge won't tell you if there's any difference in real fuel consumption, only brim to brim figures will tell you that, and only then on similar journeys.

Have no fear, i have a feeling someone will be along shortly with a link to a magical solution for this and many other problems, a link that will be ignored by everyone here and deleted in minutes by the mod.

Checking brim to brim fuel figures is the only way, just because your dash display tells you your car is doing 80mpg doesn't mean it is, and i suspect the figures now are more like reality.

Edited by gordonbennet on 12/12/2019 at 22:42

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Thu 12 Dec 2019 23:24
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - edlithgow

my VW Golf was giving me around 75 - 80 MPG on the motorway, even in cold.


No.

It wasn't

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Thu 12 Dec 2019 23:51
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - bathtub tom

It may have been! I had a neighbour with a petrol Merc who claimed such figures. Turned out he only looked at the instantaneous figure (probably when going downhill).

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Fri 13 Dec 2019 07:41
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Bolt

It may have been! I had a neighbour with a petrol Merc who claimed such figures. Turned out he only looked at the instantaneous figure (probably when going downhill).

My Civic reads 100mpg if you take your foot off the accelerator pedal for a few seconds slowing down/going downhill and some people believe what it reads

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Fri 13 Dec 2019 06:17
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - paul 1963

my VW Golf was giving me around 75 - 80 MPG on the motorway, even in cold.


No.

It wasn't

Brilliant Ed, reply of the week !

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Fri 13 Dec 2019 08:49
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Ryan71

So this was on my long 170 + mile journys and I topped up to a full tank and calculated this. The long term average would read 78 - 80ish but obvs I would get a little under that, as you clearly stated. What im saying is since the jumpstart this has reduced quite abit, and what can i do to bring my MPG back up?

Should I use a charger to charge my battery back up?

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Fri 13 Dec 2019 09:40
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Andrew-T

So this was on my long 170 + mile journeys and I topped up to a full tank and calculated this. The long term average would read 78 - 80ish but obvs I would get a little under that, as you clearly stated.

So you are suggesting that you get better than the manufacturer claims? Like Ed, I have my suspicions. Makers don't normally miss out on such opportunities. [especially with a VW .. :-( ]

Edited by Andrew-T on 13/12/2019 at 09:41

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Fri 13 Dec 2019 10:27
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Peter.N.

The colder weather will give an MPG reduction.

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Fri 13 Dec 2019 12:33
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - mcb100
NEDC and WLTP figures are based upon driving at pre-determined speeds, so if you drive more slowly than that from which the figures were taken, you’ll get better than the official numbers. They are a comparison tool, not the best a careful driver can achieve. I’d be suspicious of any claims of exceeding a manufacturer’s stated top speed, but not necessarily the quoted MPG figures.
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Fri 13 Dec 2019 15:42
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Andrew-T
NEDC and WLTP figures are based upon driving at pre-determined speeds, so if you drive more slowly than that from which the figures were taken, you’ll get better than the official numbers.

The OP told us he got his figures on long M'way trips, so I don't suppose he was travelling below the test speeds - do you?

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Fri 13 Dec 2019 15:59
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Ryan71

Thanks for the replies guys,

So in terms of MPG like i stated this has decreased after being a donar car for a jumpstart and what could I do to get this back up?

It must be that the alternator is working extra hard trying to refill the battery? Or something.

And regardless of whether i can trust the cars computer in terms of MPG the stated figure has dropped and ive noticed im using more fuel on my trips.

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Fri 13 Dec 2019 20:05
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Bolt

Thanks for the replies guys,

So in terms of MPG like i stated this has decreased after being a donar car for a jumpstart and what could I do to get this back up?

It must be that the alternator is working extra hard trying to refill the battery? Or something.

And regardless of whether i can trust the cars computer in terms of MPG the stated figure has dropped and ive noticed im using more fuel on my trips.

The battery will have been recharged by now it does it very quickly, your problem is more likely air temp difference as its colder out, when the temp goes back to normal it will return to usual MPG though doubt it will be as high as you state, cant say I know many cars that do what manufacturers state!

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Fri 13 Dec 2019 22:29
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Big John

My car now very slowly the MPG goes up and the maximum I can get out of it driving eco friendly is around 65 MPG, also when starting the car it sometimes takes a little longer on the Ignition, and when idling the MPG starts to drop, this was not the case before.

You have to be careful jumpstarting any car with stop start - on my Skoda Superb there are signs showing where to attach jump leads if someone is jumpstarting me as there is a sensor too/from the battery with extra wires from it - you may have fried this somehow. Could be worth checking with an auto electrician. Also I wonder if when jumpstarting your car you've somehow changed a stored setting. I'm presuming it has stop / start as it is a Bluemotion - also if it has stop/start is it still working?

However I must admit even for a 1.6 bluemotion the original 75-80 mpg sounds way too optimistic. How many miles did you used to get out of a full tank?

The only way of measuring mpg is by logging numerous full tank to full tank fuel used and mileage covered and do the sums.

On any car when idling and stationary the MPG will eventually drop as it's a simple equation of using fuel but covering no miles.

Edited by Big John on 13/12/2019 at 22:30

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Fri 13 Dec 2019 22:59
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Ryan71

Thank you so much for this reply and effort.

Ahhh i see, yes the stop/start still works on my car although i turned this off as i just thought it would wear the battery down further as its forced to start at every traffic light.

I see it may have affected some settings, so like ive said my trips of 180miles + did say average MPG 78ish and sometimes 80, but ofcourse this cant be tottaly accurate but from filling up the tank from just 20miles left i managed to cover a great length of miles in this car so i managed to get well into the 70s, until i topped up again. Even in winter.

Ive been driving around no sterio, phone charge, electronics in a hope my battery will fix itself

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Fri 13 Dec 2019 23:49
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Big John

Ive been driving around no sterio, phone charge, electronics in a hope my battery will fix itself

Er - negligable power consumption on these devices so I wouldn;t bother doing this. If stop start is working then battery already charged, usually if something wrong there stop start doesn't work (that's why I asked)

Edited by Big John on 13/12/2019 at 23:53

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Sat 14 Dec 2019 09:29
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Andrew-T

<< On any car when idling and stationary the MPG will eventually drop as it's a simple equation of using fuel but covering no miles. >>

I seem to remember the old thinking used to be that by switching off during many short stops, the fuel saved was needed to recharge the battery for all the restarting effort?

Of course the real purpose of stop/start is to limit pollution at congestion points.

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Thu 9 Jan 2020 12:27
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - Railroad.

Modern VAG vehicles have a Battery Energy Management (BEM) system. The vehicle must be fitted with an OEM battery, and the details including the type and serial number must be programmed into the system control unit using suitable diagnostic equipment. If this information is missing or incorrect then the vehicle will not be able to correctly manage battery resources. I'm guessing that perhaps this may have happened when you used it as a donor vehicle as your controller would've seen a different battery.

It would be worth going to a VW dealer or specialist and plugging in a scantool to check the information in the Battery Regulation controller, address 61, just in case it's different from the details of your battery.

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Fri 10 Jan 2020 09:20
VW Golf 1.6 Bluemotion - Jumpstarted friends car - lost 10MPG - piggy

What the OP's question and subsequent problem reveals is the danger in donor starting any modern car. I'm afraid my attitude to anyone asking me to jump start their car would be an outright refusal. Surely rescue organisations like the AA exist to help in such situations. They can also be held responsible for any accidental damage.

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