I have a 2013 XF 3.0 and typically the first thing I do is hit the Eco button to shut off the stop/start system because it's just annoying. Lately, I've found myself in a few situations where I could actually use it and decided to give it another try. It's been months since I've used it last. After the car auto starts, you can clearly feel the transmission engage and the car feels like someone lightly bumper tapped me from behind. Similar to if you blip the throttle in a regular automatic transmission car and then shift into drive. I don't remember it feeling so abrupt. Anyone else have this issue? I'm going to take it in and have them look at it along with some other issues, but wanted to know if I'm the only one. Let's just say I'm not off to a great start...

 

Stop start only works if the transmission is in drive. If you take it out of drive the engine restarts.

What you are feeling is perfectly normal.

The engine restarts and loads up the torque converter immediately, ready to take off. The transmission starts off in second gear normally so you will feel a push against the brake pedal.

Since you only restart by releasing the brake pedal this is not an issue, you want the car to take off immediately and this is how it is achieved.

I recommend you leave the "eco" button alone for at least a month continuously and I guarantee you will get to like this feature, and save a little fuel. More fuel is saved in heavy traffic than light traffic. In continuous stop and go the system knows not to keep stopping the engine. One of thew niftiest features of this system is it "knows" when you've parked the car. If you release your seatbelt when the stop start stops the engine it knows you intend to get out and will select P for you and turn off the car!

Also, you can effect a lot of control over the restart by learning how it responds to brake pedal pressure. Easing off the brake pressure just a bit will restart the engine but leave the brakes on hard enough to stop any forward movement of the car.

 

It's been growing on me. I've pretty much figured out how to manipulate the brake pedal to get it stop/start when I want. Nifty feature when you get used to it. Makes me feel better by not wasting away at a long red light, although I get some funny looks when it does stop and someone is next to me with their window down, haha. Makes me think just how big of an impact this could have if all cars stuck at the light with me also stopped needlessly idling. Didn't know that about the seatbelt, but completely make sense from a safety standpoint. I just hope that a software update can make the transition a little smoother.


I'm not exactly a tree-hugger, but ran across some very interesting facts from the DOE:

• A 3.0L engine idling 10 min/day will waste 29 gallons/year (0.48 gal/hr) [even more with accessories running]
• A 5.0L engine idling 10 min/day will waste 48 gallons/year (0.79 gal/hr) [even more with accessories running]
• Fuel is only partially combusted when idling because an engine does not operate at its peak temperature which leads to build up of residuals on cylinder walls that can damage engine components

Here is a link to the worksheet to calculate the total avoidable idling costs per year, including oil changes and depreciation:
http://www.transportation.anl.gov/pd...light-duty.pdf

 

I've heard a couple customers and the owner talk about the start/stop system on their Rovers. It does take some getting used to. It is a really neat system when looking at it from a technical standpoint. We all had to do in-dealer training on it. It currently cannot be changed from the default "on" from a start. Blame the EPA and fuel economy regulations for that.

 

I think I read somewhere that it really takes a tow on the battery, forcing you to replace batteries prematurely. Anyone know if this is a valid statement?

 

More misinformation probably brought on by an armchair "mechanic" or stubborn old-timer not willing to accept change...

The stop/start system is actually very sophisticated. These cars with the eco technology have two batteries. One is for starting the car, and the other is for running your accessories when the car is shut off. There are a series of checks that are made before shutting off the engine to ensure that it can reliably restart, including engine temperature and battery charge levels. If it's too hot (over 104 F) or too cold (below 32 F) outside requiring the air conditioning or heating inside, the car remains on. This also applies to ambient cabin temperature, or if the driver has set the heating and ventilation controls to a high setting. If the hood is open, the driver turns the steering wheel or has their belt unbuckled, the car will also stay running.

Jaguar's Stop/Start uses a "Tandem Solenoid Starter", allowing independent starter gear selection and engine starting. The multiple starter gears and the ability to be able to inject partial fuel charges in the cylinder allows the car to restart in multiple situations, including a car that has just shut off but the motor hasn't come to a complete stop. A more powerful and durable starter motor replaces the standard starter. This starter is designed to be able to handle the extra heat in the copper motor windings that occur from the large amount of in rush current when engaging the starter.

 

Cannot or will not? AFAIK, current BMWs can be reprogrammed so that 'off' is the default setting. Does BMW qualify for some sort of regulatory exemption or is it just a case of some are and some are not willing to break the rules?

 

And exactly how much money is parts and labor for a new starter?? I would think that wearing out the starter prematurely would cost MUCH more than the $200 annual gasoline savings.

 

See post #6 above. It's not a regular starter. It's designed for the heavy duty cycles expected in a stop/start system.

 

AFAIK, at the moment, there is no capability to change the default. I'm not saying there won't be, but considering that JLR need to meet CAFE standards, they probably will not make it easy to override.

 

This looks like a solution in search of a problem. I am sure the cost of all the R&D and heavier duty parts is much more than any savings. It's a marketing ploy, like regenerative braking.

 

I just looked up the price of replacement starters. Negligible difference in price.

'12 XF 5.0 MSRP $519.12

'13 XF 5.0 & 3.0 MSRP $544.35

 

Just as a matter of the numbers of extra start over a non-Eco system, the statement should be true. How much actually measurable effect it has on the life of the battery is unknown to me.

Look at it this way: the type of lead/acid batteries used as starter batteries do not like heavy current draws and heavy charge cycles. Such tend to degrade the lead plates that make up the battery. Yet, that is exactly what happens with engine starts. An engine would draw as much as 400+ Amps during the cranking cycle and apply heavy charges back into the battery following such large current draws. Not an ideal scenario, as far as battery life concerned, as lead/acid types favor slow discharges and charges.

The new gen XJLs are known for ultra heavy current draws just from opening doors and powering on the two displays. Lots of Low Battery warning on these cars (mine in no exception). Is it by chance that the XJL batteries are being replaced constantly? Mine was replaced at less than 10K miles that occurred 5K miles back. Now, I get battery warnings constantly AGAIN. I figure it to be due to the heavy discharge and charge cycles. My XF and XKR do not have these issues and neither one of them matches the heavy current draws of the XJL power up states.

 

Actually this is all about CO2 and climate change. Money saving isn't relevant.

I also discovered that the stop start will leave the engine off if you select neutral after the engine stops and then if you apply the EPB the engine stays off. Drawback appears to be that you need to select D before you need the engine to restart. Not sure about that last, have to experiment a bit more.

As for defeating the system by having it default to "off" that would be pointless. The system is so sophisticated it just never causes a problem. I think the auxilliary battery also powers the restart and the main battery powers the ancilliaries while the stop start is engaged and stops the engine. The auxilliary battery is possibly a glass mat type. Deep battery draw rarely occurs during starting a modern engine. Battery drawdown is only significant when ambient temperatures are very low. Restarting a hot engine needs very little battery power.

Still a great bonus is the car shuts down completely if you engage P and release your seatbelt after the engine has been stopped by the system.

 

Just a little info on the start/stop system. The main battery is always used to start the engine. There is a MOSFET (similar to audio amplifiers) system that controls the switching from the main battery to the auxiliary battery for the electrical systems that are already running when the start/stop is activated. The switching is seamless, as you can see. Also, both batteries are AGM (absorbent glass mat) batteries. I'm not sure about the Jags, but the Rovers have the auxiliary battery mounted laying flat in the right rear load space trim area.

 

Got the car back from the dealer. Said that the abruptness was typical to others on the lot and that it is a common complaint among start/stop owners. Also said that BMW's system has been getting much more complaints about its similar system. This technology is nothing new. It's tried and true technology that's been on the streets for almost two decades (hybrids use the exact same technology to stop/start their engine multiple times a trip). I think I'll be trying to take more advantage of the feature.