Acura MDX SUV Forums banner

1 - 20 of 24 Posts

·
Registered
Joined
·
68 Posts
Discussion Starter #1
2016 SH-AWD Advance/Entertainment

I bought this car last Thurs and every time I stop, this message pops up "Automatic Engine Idle Stop Unavailable". I made sure to press the button to enable it I even tried to drive no heat, no radio, no nav, etc but it's still not kicking in. I heard it sometimes doesn't work when it's really cold. But the other day when I drove it, it was above 40F. Any suggestion? I've scheduled to take it to the dealer next week.
 

·
Registered
Joined
·
94 Posts
They are several parameter that must be met before the idle stop activates

"Auto idle stop does not activate (or the engine may automatically restart) when the driver’s seat belt is unfastened, the vehicle is stopped on a steep hill, the windshield defroster is on, and other conditions. See the Owner’s Manual on the Owner information CD or at owners.acura.com (U.S.) or myacura.ca (Canada) for a full list of conditions."
 

·
Registered
Joined
·
2,793 Posts
There have been posts from other owners about the auto idle stop not working either, but they haven't been able to get resolution with Acura. I would still recommend starting the case with the dealer and escalating it through corporate. It sounds like the system is really either overactive, causing people to really hate it, or entirely inactive, which means you've basically paid for a non-functioning feature. One owner went as far as buying a Honda HDS and diagnosing himself, which lead him to a fault controller for the auto idle that he was resetting by removing/reinserting the fuse.
 

·
Registered
Joined
·
391 Posts
There have been posts from other owners about the auto idle stop not working either, but they haven't been able to get resolution with Acura. I would still recommend starting the case with the dealer and escalating it through corporate. It sounds like the system is really either overactive, causing people to really hate it, or entirely inactive, which means you've basically paid for a non-functioning feature. One owner went as far as buying a Honda HDS and diagnosing himself, which lead him to a fault controller for the auto idle that he was resetting by removing/reinserting the fuse.
wow. that's a big leap in trying to troubleshoot a vehicle issue. is honda going to reimburse him for that Honda HDS kit when the techs that honda pays(?) couldnt do it themselves? or the warranty you paid for was worth the ink that was used to print out the order form?

i was thinking of buying my own Honda HDS on ebay. but was apprehensive as to the version of the firmware currently installed and whether i could update it from Honda/Acura's website?
 

·
Registered
Joined
·
2,793 Posts
Yeah it sucks but it's the only way to get to the bottom of things sometimes (especially since Honda/Acura loves "It's normal!"). I'm also on the fence about the ebay HDS units. They look like they will work from what I see on the forums, but nobody really knows what is the latest and greatest.
 

·
Registered
Joined
·
1 Posts
I just found out at the dealer that the Auto Idle-Stop sensor will not work if the Battery internal Temperature is below 61F (16C) degrees. I just bought a 2017 Acura MDX - Advanced+Entertainment model less than a month ago, and for the time I drove it, the AIS did not work or "Unable to Activate". They ran a diagnostic test and found out that the sensor passed all tests, EXCEPT battery temp test which it failed. The temp at time of test was around 40F for the Battery Internal Temp. Technician waited for battery to continue heat-up and found that the AIS sensor activated and worked at 61F (16C). This is in the State of Virginia. Mine was fine driving home, the engine completely stopped when I am at a stoplight, and instantaneously, restart upon releasing foot pressure on brake pedal. The info board will tell you if you are not putting enough pressure on the brake pedal during a stop. I will monitor it for a while to see if this solves the AIS issue. So far it is working for me.
 

·
Registered
Joined
·
288 Posts
I had intermittent operation of the stop/start system in my 17 Advanced. Dealer re-flashed the system and it has been working reliably for about 2 weeks now. Supposedly there's some kind of TSB about it. Dealer was told what to do by Acura help team (engineering?) And my outside temperatures have been in the 30's F, and it's been working reliably after I get the car up to normal operating temp (per the temp gauge).
 

·
Registered
Joined
·
357 Posts
Mine hasn't been working for a quite a while now. One thing I noticed that it resumed it's normal operation after I did an oil change and reset the counter. It worked fine for a few short weeks then stopped again, coincidence? Perhaps. I just don't have time to waste at the dealer on this worthless feature, IMO.
 

·
Registered
Joined
·
288 Posts
I agree about its worthlessness. It was done merely to get an extra MPG rating increase. These days manufacturers are tripping all over themselves trying to satisfy the ever-increasing CAFE standards. And that's the reason why we can turn it off with the button, but it defaults back to "on" when you restart the car next time. In order for the mileage increase to count, it cannot be defeated. My feeling was that as long as I had the feature, I wanted it to work correctly.
 

·
Registered
Joined
·
288 Posts
Update March 2017 - Been to dealer several times for this and they reflash it and it will work for a week or two then stop. It's been 8 days now without ever working. Display just says system is "unavailable". Outside temps have been between 25 and 45 degrees F. And I'm not buying that post about the battery temp having to be above 61 degrees. It has worked (when it works) in temps in the 20's, 30's, 40's, and 50's (yeah, it's been a crazy winter). Just one more thing they can't fix.
 

·
Registered
Joined
·
2,613 Posts
I agree about its worthlessness. It was done merely to get an extra MPG rating increase. These days manufacturers are tripping all over themselves trying to satisfy the ever-increasing CAFE standards. And that's the reason why we can turn it off with the button, but it defaults back to "on" when you restart the car next time. In order for the mileage increase to count, it cannot be defeated. My feeling was that as long as I had the feature, I wanted it to work correctly.
I have a Bmw. The stop/start can be turned off and it stays off. It's a small car though.
 

·
Registered
Joined
·
357 Posts
Update March 2017 - Been to dealer several times for this and they reflash it and it will work for a week or two then stop. It's been 8 days now without ever working. Display just says system is "unavailable". Outside temps have been between 25 and 45 degrees F. And I'm not buying that post about the battery temp having to be above 61 degrees. It has worked (when it works) in temps in the 20's, 30's, 40's, and 50's (yeah, it's been a crazy winter). Just one more thing they can't fix.
Lemon buy back time perhaps?
 

·
Registered
Joined
·
500 Posts
I absolutely hate start/stop, so when you find out what the issue is so I can make mine unavailable all the time.
 

·
Registered
Joined
·
288 Posts
I'm not a fan of it either. It's soon gonna be hard to buy a new car without that feature, from what I'm reading in magazines. More and more models have it due to ever-tightening CAFE standards. And in my Advance, it is rated a full mpg higher because of it. And that's why you can't turn it off permanently (although if I leave it unrepaired, it's as good as permanently off <groan>). I guess if you use it to improve your mpg rating, it can't be permanently turned off. Maybe the current administration will ease the CAFE standards to more realistic levels.
 

·
Registered
Joined
·
23 Posts
Update March 2017 - Been to dealer several times for this and they reflash it and it will work for a week or two then stop. It's been 8 days now without ever working. Display just says system is "unavailable". Outside temps have been between 25 and 45 degrees F. And I'm not buying that post about the battery temp having to be above 61 degrees. It has worked (when it works) in temps in the 20's, 30's, 40's, and 50's (yeah, it's been a crazy winter). Just one more thing they can't fix.
hi guys,

i'm actually the guy from the other thread, who bought a HDS to diagnose the auto engine idle stop problem on the MDX. having it always not working and just showing "unavailable". i had to get down to the bottom of it without the help of the dealerships.

what i really found out with the HDS, is that the triggering factor (of it not working and showing "unavailable") was with the BMS (battery management system) which checks only 2 things (according to HDS info): 1. battery temperature and 2. state of charge. i checked the battery temperature from the hds reading/parameter and is at 27-28C (and i ran it a 2nd time, battery temp was at 37C) which is in normal range, but "idle stop inhibit (BMS)" is still red, so that means the auto start/stop feature isn't working because of "battery state of charge" reason. meaning the bms module does think that the battery is not fully charged. especially if there was a lot of drain on the battery while the engine was off for a long time (e.g. #1 if the idle stop was activated until the battery drained to the point that the engine restarted by itself before you got to a green light, #2 if the car was parked for a long time ("park&fly" sort of thing)with something draining the battery down) then the BmS module would think there isn't enough stored charge on the battery so it gives you "unavailable" on the dash when you come to a complete stop.

also, the alternator on these mdx's (2016 & up) are always (for most of the time) running in their "Low power output" unless you turn on (i forgot if full headlights on or full headlights on + fog lights) triggers the "high output charge" on the alternator. they somehow output just around 12.3v while you are driving with the low output mode. (i guess fuel efficiency design for honda/acura to achieve more mpg). less drag for the alternator on the engine when operating in the low power output. so the battery doesn't get charged up to the point the BmS would allow it to go to Idle stop mode. hence the "unavailable" message on the dash. charging a low charge battery at 12.3v doesn't really get it charged up quickly even if it is an AGM battery. it needs more voltage & current to get a depleted battery up quickly. high output mode usually in the mdx is around 14.something volts. and does replenish the charge between traffic light stops...


what i have done, is i have left the headlight switch on "ON" all the time + the fog lights "on" and it always triggers the high output mode of the alternator. the down side is driving with your full low beams on even in the daytime. also don't worry leaving your headlight switch to the "on" position, as when you get off the mdx (it will chime to remind you the switch is still "on") and park it, the bms module will shut the headlights off after 1 minute of locking the doors.

after leaving the headlight switch on the "on" position all the time (24/7), the idle stop always works 100% of the time.

i even went the length of plugging in the battery when i get home to a smart charger just to make sure in the morning when i wake up, the AGM battery is fully topped off. but you don't have to go that route. too overkill in my opinion.



so the short solution to this "unavailable" problem is to keep your headlight switch on the ON position i guess.


so let us know if that works for you,
we'd like to hear feedback

thanks,
hope this info helps


jeffrey
 

·
Registered
Joined
·
2,613 Posts
hi guys,

i'm actually the guy from the other thread, who bought a HDS to diagnose the auto engine idle stop problem on the MDX. having it always not working and just showing "unavailable". i had to get down to the bottom of it without the help of the dealerships.

what i really found out with the HDS, is that the triggering factor (of it not working and showing "unavailable") was with the BMS (battery management system) which checks only 2 things (according to HDS info): 1. battery temperature and 2. state of charge. i checked the battery temperature from the hds reading/parameter and is at 27-28C (and i ran it a 2nd time, battery temp was at 37C) which is in normal range, but "idle stop inhibit (BMS)" is still red, so that means the auto start/stop feature isn't working because of "battery state of charge" reason. meaning the bms module does think that the battery is not fully charged. especially if there was a lot of drain on the battery while the engine was off for a long time (e.g. #1 if the idle stop was activated until the battery drained to the point that the engine restarted by itself before you got to a green light, #2 if the car was parked for a long time ("park&fly" sort of thing)with something draining the battery down) then the BmS module would think there isn't enough stored charge on the battery so it gives you "unavailable" on the dash when you come to a complete stop.

also, the alternator on these mdx's (2016 & up) are always (for most of the time) running in their "Low power output" unless you turn on (i forgot if full headlights on or full headlights on + fog lights) triggers the "high output charge" on the alternator. they somehow output just around 12.3v while you are driving with the low output mode. (i guess fuel efficiency design for honda/acura to achieve more mpg). less drag for the alternator on the engine when operating in the low power output. so the battery doesn't get charged up to the point the BmS would allow it to go to Idle stop mode. hence the "unavailable" message on the dash. charging a low charge battery at 12.3v doesn't really get it charged up quickly even if it is an AGM battery. it needs more voltage & current to get a depleted battery up quickly. high output mode usually in the mdx is around 14.something volts. and does replenish the charge between traffic light stops...


what i have done, is i have left the headlight switch on "ON" all the time + the fog lights "on" and it always triggers the high output mode of the alternator. the down side is driving with your full low beams on even in the daytime. also don't worry leaving your headlight switch to the "on" position, as when you get off the mdx (it will chime to remind you the switch is still "on") and park it, the bms module will shut the headlights off after 1 minute of locking the doors.

after leaving the headlight switch on the "on" position all the time (24/7), the idle stop always works 100% of the time.

i even went the length of plugging in the battery when i get home to a smart charger just to make sure in the morning when i wake up, the AGM battery is fully topped off. but you don't have to go that route. too overkill in my opinion.



so the short solution to this "unavailable" problem is to keep your headlight switch on the ON position i guess.


so let us know if that works for you,
we'd like to hear feedback

thanks,
hope this info helps


jeffrey
Anything that is on uses more power and therefore more gas. That’s why mileage improves when the ac is not on. So having the headlights on uses more gas. It may very well negate the stop/start working.
 

·
Registered
Joined
·
288 Posts
Lots of good info you provided. I do believe it's the "state of charge". Once the dealer told me about the de-coupling alternator (yes, for gas mileage) it made more sense to me. They even bought me a battery maintainer and connected the quick-connect harness to the charging system so I could just pop the hood and plug in. That's fine but having to plug the car in at night... might as well buy a Tesla <grin>.
 
1 - 20 of 24 Posts
Top